11 of the Best Light Meters for Houseplants and Indoor Gardening

You may have heard that a light meter is an incredibly helpful tool to keep your houseplants happy or to assist you in attaining indoor gardening excellence – almost like a magic wand!

But these tools come with a variety of features and are available at a wide range of price points – as low as 15 US dollars or so, and up into the thousands.

So when it comes to using a light meter for houseplant care or other indoor gardening pursuits, you may find yourself wondering what the difference is between the various options.

And the sheer number of different models may leave you wondering which one to choose.

A close up vertical image of a light meter set on a countertop surrounded by houseplants, pictured in bright sunshine. To the top and bottom of the frame is green and white printed text.

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Help is here! This article is going to walk you through 11 different light meter options for houseplant gardeners and indoor growers, explaining the pros and cons of each device, so you can easily compare and contrast them.

Before we look at the top selections, let me go over the features we’ll be examining.

You’ll find out about the housing material, color, dimensions, and weight of each device. I’ll also let you know which units of measure it uses, as well as its measuring range.

You’ll learn about the display type, how the model is powered, and – if a battery is needed for operation – whether the battery cover slides off or requires a screwdriver. (This last point is a personal pet peeve of mine – I’m not thrilled when I have to find a screwdriver to change out a failing battery!)

I’ll also let you know whether the luminosity sensor (the part of the device which detects light) comes with a protective cap or not, as well as whether the sensor is built into the device or separate, attached by a cord.

While some gardeners and growers may prefer a compact, all-in-one device with a built-in sensor, I consider a detached sensor to be a plus since it allows for more flexibility when taking measurements.

A close up horizontal image of a light meter with a reading of 384fc next to potted lettuce.
Photo by Kristina Hicks-Hamblin.

For light meters with detached sensors, I’ll let you know how long the cable is and whether this cable is coiled or straight. I also consider straight cables to be a positive since the coiled ones can limit one’s reach.

And of course, we’ll also be looking at the various functional features of each model.

We’ll investigate what types of light sources can be measured accurately, such as sunlight versus different types of electric bulbs.

You’ll also learn whether each device features some of these common options: holding current readings, holding peak or low readings, logging data, and calculating a daily light integral (DLI), which gives you the average light exposure over the course of one day.

We’ll also consider the accuracy or measurement uncertainty of each model. Manufacturers have tested their devices in this regard and are able to state that the device is accurate, for instance, within a 4% margin of error. The lower the number, the more accurate the device.

In addition to these operating functions, I’ll let you know what type of accessories come with each device, and finally, I’ll give you an idea of what to expect in terms of pricing.

Okay, houseplant parents and indoor gardeners, are you ready to get started? Here’s a quick peek at our list of selections:

Now that you have an idea of what features we’ll be exploring, here are a few questions for you to consider when choosing a light meter to use for houseplant care or other adventures in indoor gardening.

You may want to grab your trusty gardening notebook to jot down the answers before we move forward.

Do you want to perform a simple check to make sure your houseplants are getting the right amount of sunlight? Or are you interested in a tool that will help you cultivate houseplants or indoor crops under grow lights with the best results?

The answers to these questions may determine whether you should choose a pricey PAR light meter or an inexpensive device that measures in foot candles and lux – or something in between.

Let me flesh out the differences for you.

Some meters use a silicon photodiode to measure light in foot candles and lux, providing measurements that are more pertinent to the human eye than to the way plants use light for photosynthesis.

They measure illuminance, that’s to say, how much light illuminates a surface.

However, these types of light meters are usually adequate for houseplant gardeners whose plants grow in the glow of natural sunlight or with the additional luminosity of non-LED grow lights.

These devices represent the most affordable options, and their pricing starts at about 15 dollars.

A close up horizontal image of a light meter with a reading of 518 fc set next to houseplants.
Photo by Kristina Hicks-Hamblin.

On the other hand, for houseplant growers or indoor gardeners using a selection of LED grow lamps, a PAR (photosynthetically active radiation) light meter tends to be a more desirable solution.

These devices display units in PPFD (photosynthetic photon flux density), offering more accurate measurements of the light that plants can actually use than meters that measure in foot candles or lux.

That’s because these meters measure photosynthetically active radiation – that’s to say, light that plants can use for photosynthesis. These devices employ quantum sensors that count photons – which is something that the lux and foot candle meters don’t do.

However, PAR devices require a more significant monetary investment, starting at about 150 dollars and going up into the thousands.

Before you jump to the conclusion that a PAR light meter must be the better one for your gardening hobby, first check the horticultural references you rely on – which light exposure units do they use?

Foot candles tend to be the unit par excellence among many US-based horticulturalists and county extension programs, so if you rely on these sources for gardening or agricultural guidance, a meter that displays measurements in foot candles may be more convenient.

Of course, it’s possible to convert PPFD to foot candles, but this isn’t a straightforward affair, since conversion differs depending on the light source.

You’ll find a more in-depth explanation of these different types of devices in our article on how to use a light meter for houseplants and indoor gardening. I highly recommend reading that guide before choosing a device so you’ll know what to expect!

Now let’s get started with learning about how these different devices can help you in your houseplant growing or indoor cultivation adventures!

1. Amprobe LM-200

If checking luminosity from LED grow lamps is on your indoor gardening and houseplant care to-do list, the Amprobe LM-200 LED light meter, available from Amazon, can help you with that task.

This device has a red plastic housing, measuring 5.1 inches long, 2.5 inches wide, and 1.5 inches deep. It weighs 7.76 ounces.

This meter has a digital display, and a measuring range of 0 to 20,000 foot candles or 0 to 200,000 lux.

Amprobe LM-200

Powered by a nine-volt battery, it is equipped with a battery cover that easily slides on and off – no screwdriver needed.

The sensor is detached, includes a protective cap, and is connected with a coiled cord that can be stretched up to five feet long.

As for operation, different buttons allow the user to choose the measurement range or to toggle between lux and foot candles.

The device has a hold button to freeze the current reading, as well as a maximum hold button to capture the highest reading.

The Amprobe LM-200 LED is most accurate when measuring white LED lamps, with a margin of error at around 3%. When measuring other light sources, it is less accurate, with an error margin of approximately 8%.

This device can be mounted on a tripod, comes with a black soft case and a nine -volt battery, and is available at an intermediate price point.

Features

  • Dimensions: 5.1” x 2.5” x 1.5”
  • Weight: 7.76 ounces
  • Units: Foot candles, lux
  • Range: 0-20,000 foot candles

Pros

  • Battery cover slides off 
  • Detached sensor
  • Sensor cover
  • Measures luminosity from white LEDs most accurately
  • Mountable on tripod (not included)
  • Carrying case included with purchase
  • Comes with a 1-year warranty

Cons

  • Coiled sensor cord
  • Less accurate for all sources except white LEDs
  • Does not calculate DLI
  • No data logging

Think one of these bad boys needs a place in your indoor gardening or houseplant care tool kit?

You’ll find the Amprobe LM-200 light meter available for purchase from the Amprobe Store via Amazon.

2. Apogee Instruments MQ-500

The MQ-500 from Apogee Instruments, available via Amazon, is a lightweight PAR meter that can accurately measure light from all sources, including photosynthetically active radiation in the range of 400 to 700 nanometers.

Sporting an anodized aluminum body, the housing is gray, yellow, and white, and it features a digital display.

The MQ-500 has a measuring range of 0 to 4000 micromoles per second per meter squared. It’s 9.69 inches long, 6.38 inches wide, 2.32 inches thick, and weighs 6.4 ounces.

Apogee Instruments MQ-500

This device is powered by a CR2320 coin cell battery, and the battery cover screws on and off.

It features a detached sensor that has a straight, 78-inch-long cord, and comes with a protective sensor cap. The sensor can be attached to an optional telescoping wand that extends up to 33 inches for more controlled measurements beyond arm’s reach.

The device has four operating buttons in addition to the power button. The mode button provides access to the main menu, up and down arrow buttons allow the user to make selections from the menu, and the sample button allows the user to take manual readings.

Gardeners can easily log data with this light meter, which will take a sample every 30 seconds for 24 hours, and it can store up to 99 measurements. Downloading this data to a computer requires an additional cable which is not included with purchase.

Data can be downloaded to both PCs and Macs, and this model has a calibration uncertainty of approximately 5%.

This product is made in the USA, and comes equipped with a battery and a black neoprene case.

As far as the price goes, the MQ-500 represents a significant financial investment, but it is a mid-range selection for a PAR light meter.

Features

  • Dimensions: 9.69” x 6.38” x 2.32”
  • Weight: 6.4 ounces
  • Units: PPFD
  • Range: 0-4000 µmol/(m^2/s)

Pros

  • Lightweight
  • Separate sensor
  • Straight sensor cord, optional telescoping wand
  • Sensor cover
  • Accurately measures luminosity from all sources
  • Enables data logging on PCs and Macs
  • Calculates DLI
  • Made in the USA
  • Comes with a 4-year warranty

Cons

  • Battery cover requires screwdriver
  • Fairly expensive
  • Need one of these to improve your indoor gardening game?

Purchase the MQ-500 PAR meter – with or without the telescopic sensor wand – from the Apogee Instruments Store via Amazon.

3. Dr. Meter LX1330B

An affordable and dependable option for measuring foot candles and lux, Dr. Meter’s LX1330B, available via Amazon, is perhaps one of the most widely used light meters among houseplant parents.

The dark gray plastic housing has orange accents and a removable orange silicone grip case.

It weighs 10.5 ounces and measures ‎5.86 inches long, 2.79 inches wide, and 1.61 inches thick.

Featuring a digital display, the Dr. Meter LX1330B has a range of 0 to 20,000 foot candles or 0 to 200,000 lux.

Dr. Meter LX1330B

The LX1330B is powered by a nine-volt battery, with a battery cover that screws on and off.

It has a detached sensor on a coiled cord that can be stretched up to 69 inches, and comes with a protective sensor cap.

This device measures luminosity from the sun and many types of electric bulbs, but is not recommended for measuring the output of LEDs.

In addition to the power button, four other buttons allow the user to choose the measurement range, toggle between foot candles and lux, hold a current reading, or capture a peak reading.

The margin of error is approximately 3% for readings below 2000 foot candles, and approximately 5% for readings above 2000 foot candles.

This model also has a plastic fold-out stand, an additional feature that allows for extra ease of use.

This budget option comes with the battery needed to get it started as well as a screwdriver for removing the battery cover.

Features

  • Dimensions: 5.86” x 2.79” x 1.61”
  • Weight: 10.5 ounces
  • Units: Foot candles, lux
  • Range: 0-20,000 foot candles

Pros

  • Separate sensor
  • Sensor cover
  • Folding stand
  • Budget-friendly
  • Comes with a 1-year warranty

Cons

  • Battery cover requires screwdriver
  • Coiled sensor cord
  • Not designed for measuring luminosity from LEDs accurately
  • Does not calculate DLI
  • No data logging

Ready to add this tool to your houseplant care kit?

Get the Dr. Meter LX1330B light meter from the Dr. Meter Store via Amazon.

4. Dr. Meter LX1332B

Another tool from Dr. Meter, available via Amazon, to help with houseplants and indoor gardening, the LX1332B has similar attributes to the previous selection with a few differences.

Unlike the previous selection, this one is mountable on a tripod, has a built-in sensor, and features a more subdued color than the LX1330B’s bright orange – this one is dark blue.

Made with a plastic housing, the Dr. Meter LX1332B weighs 9.1 ounces and measures 7.3 inches long, 2.7 inches wide, and 1.5 inches thick.

This option has a range of 0 to 200,000 lux or 0 to 20,000 foot candles, and features a backlit digital LCD display.

Dr. Meter LX 1332B

A screwdriver is required to remove or replace the nine-volt battery. The built-in sensor on this model can be rotated, and it comes with a protective sensor cap.

This device accurately measures luminosity from sunlight, fluorescent, metal halide, incandescent, and high-pressure sodium lamps but not LEDs.

In addition to the power button, this model features a range button and a button that allows the user to display readings in lux or foot candles, as well as a hold button to pause the display on a given reading.

With a margin of error of approximately 4% for readings under 2000 foot candles, this increases to 5% for readings above 2000 foot candles.

Mountable on a tripod, this budget-friendly option comes with a soft pouch, and one nine-volt battery.

Features

  • Dimensions: 7.3” x 2.7” x 1.5”
  • Weight: 9.1 ounces
  • Units: Foot candles, lux
  • Range: 0-20,000 foot candles

Pros

  • Mountable on tripod (not included)
  • Rotating sensor
  • Sensor cap
  • Budget-friendly
  • Comes with a 1-year warranty

Cons

  • Battery cover requires screwdriver
  • Sensor attached
  • Not designed for measuring luminosity from LEDs accurately
  • Does not calculate DLI
  • No data logging

Feeling fond of this simple and subdued option for indoor gardening and houseplant care?

You’ll find the Dr. Meter LX 1332B light meter available for purchase from the Dr. Meter Store via Amazon.

5. Extech LT45 LED

If you use LED grow lamps with your houseplants or indoor crops and are interested in saving the data from your readings, consider this next selection a worthy candidate.

Extech’s LT45, available via Amazon, is a light meter whose specialty lies in measuring output from different colored LED bulbs.

The device is housed in dark green plastic, weighs 14.11 ounces, and measures 5.1 inches long, 2.2 inches wide, and 1.5 inches deep.

It displays a wide measuring range of 0 to 40,000 foot candles or 0 to 400,000 lux, and has a digital display.

Extech LT45

Powered by a nine-volt battery, this model has a battery cover that easily slides on and off.

The detached sensor is held on a coiled cable that expands to 59 inches long, and includes a protective sensor cap.

The LT45 has six buttons in addition to its power button, more operating buttons than most of the other models on our list.

These buttons provide the user with many different functions, including toggling between measurement units; zeroing out the calibration; recording minimum, average, or maximum readings; storing readings; holding readings; or selecting for different sources of luminosity.

This last feature makes this device different from the other selections in this roundup – in order to accurately measure the output of different types of LED bulbs, the user must select the LED color being measured – white daylight, amber, green, red, or blue.

That means you can’t get an accurate measurement of the combined luminosity of different colored LEDs all at once with this model – if that’s the feature you need, you should turn to a PAR device.

On the other hand, if you are working with one color of grow lights and plan to use this device to check their output, this may be the perfect light meter for that task.

Keep in mind that this device has a calibration uncertainty of roughly 3% for LEDs and 6% for other sources.

This model can store up to 99 readings in its memory, but with no computer interface, they will need to be noted down manually.

The Extech LT45 is a mid-range option that comes with a hard case and the battery needed to get the show on the road.

Features

  • Dimensions: 5.1” x 2.2” x 1.5”
  • Weight: 14.11 ounces
  • Units: Foot candles, lux
  • Range: 0-40,000 foot candles

Pros

  • Very wide measuring range
  • Battery cover slides on and off
  • Separate sensor
  • Sensor cap
  • Accurately measures luminosity from separate LED lamp colors
  • Enables data logging
  • Includes a 2-year warranty

Cons

  • Heavy
  • Light source has to be selected
  • Sensor cord coiled
  • Logged data is not transferable to computer
  • Does not calculate DLI
  • Less accurate for non-LED sources
  • Less accurate when measuring a combination of LED colors

Does this seem like it would be an excellent addition to your indoor gardening equipment kit?

Head to Amazon to purchase the LT45 light meter from Extech.

6. Hopoocolor OHSP350P

An exciting selection for the indoor gardener or houseplant parent with advanced lighting requirements, Hopoocolor’s OHSP350P, available via Amazon, serves not just as a PAR light meter but also works as a spectrometer.

Made from aluminum, this silver and black model is 5.45 inches long, 3.1 inches wide, and 0.9 inches thick, and it weighs 15.17 ounces.

The OHSP350P offers the best of both light measuring worlds, with a color touch screen that shows measurements in PPFD, and in foot candles and lux.

It has a measurement range between 5 and 200,000 lux or up to 8000 micromoles per second per meter squared.

Hopoocolor OHSP350P

One of the advantages of this device is that it comes with a power adapter, and the battery is built in and rechargeable.

On the other hand, a potential downside (depending on your preferences) is that the sensor is fixed on the top of the device, limiting flexibility somewhat. Also, there is no protective sensor cap.

This is nonetheless an incredible tool – the Hopoocolor OHSP350P measures photosynthetically active radiation from all sources including sunlight, fluorescents, LEDs, and all other types of electric bulbs.

And unique among the selections in this article, a built-in spectrometer analyzes the different colored wavelengths being emitted, which can be visualized in several different graphic styles on the touch screen.

This spectrometer will be useful for growers who wish to monitor or control the types of light waves in the color spectrum that their plants are being exposed to.

Using the single test function, a reading is captured at a moment in time, and this reading can then be stored if desired, but the device also allows for continuous testing. Timed intervals for continuous tests are adjustable.

The Hopoocolor can be used for data logging on PCs, but not Macs. Readings are stored on a removable eight-gig memory card and can also be transferred to PC via a mini USB cable.

This meter does not calculate DLI, and it has a calibration uncertainty of approximately 4%.

This high-end device comes with an eight-gig memory card and mini USB cable. It also features a slot for a wrist strap (not included) and comes with a carrying case.

While this device has many options for taking measurements, these may be overwhelming for some users.

Also, purchasers should be aware that English language support for the Hopoocolor OHSP350P via customer service seems to be fairly limited at this time.

Features

  • Dimensions: 5.45” x 3.1” x 0.9”
  • Weight: 15.17 ounces
  • Units: PPFD, foot candles, lux
  • Range: 5-20,000 foot candles, 0.01-8000 µmol/(m^2/s)

Pros

  • Rechargeable battery
  • Allows visualization of light spectrum
  • Accurately measures luminosity from all sources
  • Enables data logging to PCs
  • Includes a 2-year warranty

Cons

  • Heavy
  • Sensor attached
  • No sensor cover
  • English language customer service may be limited
  • Does not calculate DLI
  • Data logging not compatible with Mac
  • Expensive

Ready to get serious with your indoor growing or houseplant gardening hobby and take advantage of the many features this device offers?

You can purchase the OHSP350P spectrometer from the Hopoocolor Store via Amazon.

7. Hydrofarm Analog Active Eye LG17000

Our next selection is a very lightweight, compact, and affordable option for the houseplant parent or indoor gardener. It also requires no batteries or electricity!

Part of Hydrofarm’s Active Eye line, their LG17000 model, available via Amazon, is housed in black plastic and has a white, analog display. It measures 3.5 inches long, 2 inches wide, and 1.5 inches thick, and it weighs just 2.4 ounces.

Hydrofarm LG17000 Active Eye

When you use the LG17000, no energy source is needed. It works without power, and the device has a measuring range of up to 5,000 foot candles or 50,000 lux.

The sensor on this model is integrated, and it can be used to measure luminosity from sunlight or non-LED lamps.

This device is fairly simple – it has one knob with four settings. The first twist of the knob turns the light meter on and takes readings in the lowest measurement range, between 0 and 250 foot candles, or low light situations.

Turn the knob again, and you are expected to multiply the reading on the display by 10. This range is used to measure moderate light intensity.

Another turn of the knob and you’ll find yourself in the highest measuring range, where readings are multiplied by 100. This range is for intense luminosity such as direct sunlight.

This model has a calibration uncertainty of approximately 2%, and with its straightforward functions, it offers an excellent value at a very low price.

Features

  • Dimensions: 3.5” x 2” x 1.5”
  • Weight: 2.4 ounces
  • Units: Foot candles, lux
  • Range: 0-5,000 foot candles, 0-50,000 lux

Pros

  • Very lightweight
  • Small, compact size
  • No power needed
  • Very affordable price point
  • Includes a 2-year warranty

Cons

  • Measuring range is limited to only 5000 foot candles
  • Sensor attached
  • Not designed for measuring luminosity from LEDs accurately
  • Does not calculate DLI
  • No data logging

Do you like the affordability and practicality of this device to help ensure adequate luminosity for your houseplants or indoor crops?

Find the Hydrofarm Active Eye LG17000 light meter available for purchase via Amazon.

8. Hydrofarm Digital Active Eye LG17010

If you appreciate the simplicity and affordability of our last option, but prefer a digital display for caring for your houseplants or indoor garden crops, you’ll want to check out this next selection.

Another option from Hydrofarm’s Active Eye line, the LC17010, available via Walmart, is a battery-operated model in a plastic housing that’s black with silver and green accents.

Weighing just 4.8 ounces and measuring 6.0 inches long, 3.3 inches wide, and 2.1 inches deep, this device measures up to 40,000 foot candles or 400,000 lux.

This selection measures luminosity from sunlight and non-LED lamps.

A close up of the Hydrofarm Active Eye LG17010 Digital Hand Held Sunlight Meter isolated on a white background.

Hydrofarm Active Eye LG17010

The LC17010 is powered with a CR2032 coin cell battery, and the cover easily slides off.

The sensor is detached from the main unit, and held by a coiled cord that stretches to approximately three feet long.

In addition to its power button, this model has four additional buttons – a mode button to switch between lux and foot candles, a hold button to freeze a given reading, and up and down buttons.

These up and down buttons are used to review readings, which are automatically recorded in the device’s memory. If more than 50 readings are taken, the older ones will be replaced by more recent ones.

Stored readings can be erased by removing and re-inserting the battery.

Speaking of batteries, this product does not come with one, so make sure to add a CR2032 to your cart when making your purchase.

This model boasts a high degree of accuracy, with a calibration uncertainty of just 1%.

Expect to find the LC17010 at a price point that’s easy on the wallet.

Features

  • Dimensions: 6.0” x 3.3” x 2.1”
  • Weight: 4.8 ounces
  • Units: Foot candles, lux
  • Range: 0-40,000 foot candles

Pros

  • Lightweight
  • Measuring range up to 40,000 foot candles
  • Battery cover slides off
  • Separate sensor
  • Enables data logging
  • Affordable price point

Cons

  • Sensor cord coiled
  • Not designed for measuring luminosity from LEDs accurately
  • Does not calculate DLI
  • Logged data is not transferable to computer

Have your eye on this model to assist you in growing stellar houseplants or fabulous indoor garden crops?

Purchase the Hydrofarm Active Eye LG17010 light meter from Hydrofarm via Walmart.

And don’t forget your battery, also available for purchase at Walmart.

9. Photobio LGBQM2

Another selection from Hydrofarm from their Phantom collection, the Photobio LGBQM2 model, available via Amazon, is a low-priced PAR light meter for indoor gardeners and houseplant parents who want an accurate assessment of luminosity from all sources.

With a white plastic housing, this device measures 4.5 inches long, 2.4 inches wide, and 0.94 inches thick. It weighs 3.5 ounces without the batteries or cable.

This model has a digital display and is able to take readings in a range between 0 and 3,999 micromoles per second per meter squared.

Photobio LGBQM2

The Photobio LGBQM2 is powered by two AAA batteries, which are easy to change thanks to a sliding battery cover.

This PAR light meter comes with a detached sensor, and unlike any of the other models in this article, users have a choice of two interchangeable sensor cables – one coiled cable that is 4.9 feet long, as well as a straight, 12-foot-long cable.

Adding an additional element of flexibility to using this device, the sensor can be mounted on a tripod or selfie stick via a screw mount.

As a PAR light meter, this device will measure luminosity from all sources, including sunlight, fluorescents, LEDs, and other types of electric bulbs.

As for operating the Photobio LGBQM2, in addition to the side power button, the device has four buttons on its face: mode, enter, an up arrow button, and a down arrow button.

The enter button serves as a hold button on this model to freeze a given reading. The mode button allows one to calibrate, log, or return the device to factory settings. And the up and down buttons permit the user to cycle through recorded readings.

And users can manually record up to 99 readings – on this device the down button is pressed to record a reading while taking samples.

The Photobio LGBQM2 comes with a padded soft case, and the two AAA batteries needed to get it into action.

This device has an error margin of approximately 5%, and is an affordable option for a PAR light meter.

Features

  • Dimensions: 4.5″ x 2.4″ x 0.94″
  • Weight: 3.5 ounces
  • Units: PPFD
  • Range: 0-3,999 µmol/m^2/s

Pros

  • Lightweight
  • Accurately measures luminosity from all sources
  • Battery cover slides off
  • Separate sensor
  • Two interchangeable sensor cables included
  • Manually log up to 99 readings
  • Sensor is mountable on a tripod or selfie stick
  • Affordable for a PAR meter
  • Includes a 1-year warranty

Cons

  • No sensor cover
  • Does not calculate DLI
  • Logged data is not transferable to computer

Can’t wait to try this light meter out with your indoor grow setup or houseplants?

Get the Photobio LGBQM2 PAR meter from Amazon.

10. SpotOn Quantum PAR

The SpotOn from Innoquest is a petite PAR meter that offers simple, straightforward operation with an innovative design, making it an excellent choice for the discerning houseplant gardener or indoor grower.

This tiny PAR light meter, available via Amazon, is black with red and white accents, and measures 5.75 inches long, 1.75 inches wide, and 0.85 inches thick. It weighs in at just 2.71 ounces and is the perfect size to slip into a pocket.

The SpotOn has a digital display and a measuring range of 0 to 6,500 micromoles per square meter per second.

SpotOn Quantum Par Meter

This model is powered by a CR2032 coin cell lithium battery which the manufacturers say has a two year life in this unit, even with heavy use.

Interestingly, the battery cover is not hidden on the back of the device as with most tools of this sort. Instead it is smack dab on the front, and even has the battery type clearly printed right under the cover so you won’t be left wondering which type to buy.

The battery cover can be removed by placing the edge of a coin into the slot and twisting it off.

This model has an integrated sensor, but to make its use more flexible, the light meter can be attached to an extension wand (not included) for taking readings beyond arm’s reach. The sensor comes equipped with a cover.

As a PAR meter, this device will accurately measure light from all sources, including sunlight, fluorescents, LEDs, and other lamps as well.

This model doesn’t have any way of freezing or holding a reading, so readings will need to be noted down by hand.

The SpotOn has three modes of operation – instant spot measurement for taking a sample, scan mode for averaging luminosity in a given area, and DLI mode. This latter is the default mode for the device, and is calculated over a 24 hour period.

One of the innovative features of this model is its mounting bracket, which can be used in three different ways – as a stake, a stand, or a hanging bracket.

In addition to those options, the screw that holds the bracket on the back of the device is magnetic, offering yet another means of hanging it, such as on a metal post.

The SpotOn is water resistant, and comes with a soft carrying case as well as the required coin cell battery. The error margin for this model is approximately 5%.

This device is made in the USA and the manufacturer offers US-based customer service from their headquarters in Woodstock, Illinois. It is available at a moderately low price point for a PAR meter.

Features

  • Dimensions: 5.75″ x 1.75″ x 0.85″
  • Weight: 2.71 ounces
  • Units: PPFD
  • Range: 0-3,999 µmol/m^2/s

Pros

  • Extremely lightweight
  • Can easily be carried in a pocket
  • Simple and intuitive to use
  • Accurately measures luminosity from all sources
  • Includes a sensor cover
  • Water resistant
  • Calculates DLI
  • Made in the USA
  • Fairly affordable
  • Includes a 1-year warranty

Cons

  • Sensor attached
  • No data logging

Would this tool that’s both simple and innovative assist you in cultivating your passion for houseplants or indoor gardening?

If so, you can purchase the SpotOn Quantum Par Meter from the FGI Store via Amazon.

SpotOn Quantum Par Meter Extension Wand

And if you want that handy extension wand for taking measurements in harder to reach spots, you’ll find one of these available from the FGI Store too, via Amazon.

11. Uni-T UT383

All those state of the art PAR light meters are impressive, but some of us houseplant parents and indoor gardeners don’t need such sophisticated tools, or may not be feeling as carefree with our hard earned cash.

So if you’d like a small, inexpensive device to measure foot candles or lux that is powered by AAA batteries instead of nine-volts, you’ll want to have a look at this last selection.

The UT383 from Uni-T, available via Amazon, has a plastic housing that is red and black, weighs just 4.2 ounces, and measures 6.2 inches long, 1.9 inches wide, and 1.1 inches thick.

This device has a range of up to 18,500 foot candles and a backlit digital display.

Uni-T UT383

This model is powered by three AAA batteries, which are easy to replace since the battery cover slides on and off.

The sensor is attached, and this device measures natural sunlight and luminosity from non-LED lamps.

The UT383 has a unit button to toggle between foot candles and lux, as well as a hold button to allow the user to freeze any reading.

It also has a min/max button which allows indoor gardeners to freeze the reading on the lowest detected reading, or the highest one during a sampling session.

The margin of error for this model is roughly 4% for readings under 999 foot candles, and approximately 5% for those above 999 foot candles.

This budget model comes with the batteries you’ll need to start taking your first readings.

Features

  • Dimensions: 6.2″ x 1.9″ x 1.1″
  • Weight: 4.2 ounces
  • Units: Foot candles, lux
  • Range: 0-18,500 foot candles

Pros

  • Lightweight
  • Powered with AAA batteries
  • Battery cover slides off
  • Affordable price point

Cons

  • Sensor attached
  • Not designed for measuring luminosity from LEDs accurately
  • Does not calculate DLI
  • No data logging

Does this lightweight and affordable option seem like just the tool for your houseplant care or indoor gardening routines?

Buy the UT383 light meter from the Uni-T Store via Amazon.

Which Is the Magic Wand for You?

We’ve gotten up close and personal with 11 different light meters.

After considering these different options, as a houseplant gardener or indoor grower, does one of these “magic wands” seem to be beckoning to you?

A close up horizontal image of a light meter set in a sunny location surrounded by houseplants.
Photo by Kristina Hicks-Hamblin.

As a reminder, if you are interested in measuring luminosity from LED grow lamps as accurately as possible, make sure to choose a PAR meter, or a device that reads foot candles and lux but is specified for LEDs.

On the other hand, if you’re only measuring natural sunlight and budget is your primary concern, you have plenty of options here!

Did this article help you zero in on the device of your houseplant care dreams? Have you had any experience using any of these models for indoor gardening that you’d like to share with our readers? Let us know in the comments section below.

Now that you’ve chosen your trusty luminosity-detecting tool, can I interest you in more houseplant and indoor gardening gear? You may be interested in reading these guides next:

Photo of author
Kristina Hicks-Hamblin lives on a dryland permaculture homestead in the high desert of Utah. She is a Certified Permaculture Designer, holds a Certificate in Native Plant Studies from the University of North Carolina Botanical Gardens, a Landscape for Life certificate through the Lady Bird Johnson Wildflower Center and the United States Botanic Garden, and a Bachelor of Arts degree in liberal studies from the University of North Carolina at Greensboro. Kristina strives towards creating gardens where there are as many birds and bees as there are edibles.
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Kat
Kat (@guest_40544)
1 month ago

Hmm, I wonder what the cheapest option (that works) is if you want to leave it out all day to see how many hours you get? These are way more than I need. The cheap ones on Amazon got terrible reviews for accuracy.