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MQ-500: Full-Spectrum Quantum Meter

Make:  Apogee                                           Model:  MQ-500
✅ Incoming and reflected PPFD over and under plant canopies.
✅ Measure photosynthetically active radiation.
✅ Full spectral response sensor.
✅ Offers a self-cleaning.
✅ Long-term non-stability determined from multiple replicate quantum sensors.

FOR SCIENTISTS & SERIOUS GROWERS – The MQ-500 full-spectrum quantum meter is the premium tool of choice among leading scientists and serious growers for accurately measuring the photosynthetically active radiation (PAR) from all light sources. An accurate quantum light meter is critical for measuring the intensity of light used in the precision growing of plants and other photosynthetic organisms in greenhouses, growth chambers, farms, gardens, aquariums, and other agricultural systems.

QUANTUM LIGHT METER – Unlike commonly available LUX or footcandle meters used for measuring light for human vision, our meters feature a laboratory-grade PPFD (photosynthetic photon flux density), or “quantum,” optical detector precisely calibrated to measure the light intensity in µmol m-2 s-1 of the specific color wavelengths emitted by LEDs, HPS, MH, sunlight and other light sources that are utilized by plants for photosynthesis.

RUGGED & EASY TO USE – Quantum sensor uses a precision silicon photodiode detector, a custom optical filter, and an acrylic diffuser all housed in a self-cleaning, dome-shaped, anodized aluminum sensor head.  The sensor head is potted solid with epoxy for years of use in harsh environments, including underwater. The handheld meter is attached by a cable and displays real-time readings, records samples, and logs average intensity and daily light integral (DLI) measurements. Unlike the sensor head, the handheld meter is not waterproof.

EXTREMELY ACCURATE & STABLE – Precisely measures and combines the intensity of all photons between 400 and 700 nm to give a single PAR reading in µmol m-2 s-1 within 5 % uncertainty. Unlike hobby-grade PAR meters, our meter has a stable, accurate calibration with an accuracy drift rate of less than 2 % per year.

THREE MEASUREMENT MODES – The meter has a spot measurement, sample, and log mode and will record an integrated daily total in mol m-2 s-1. Sample mode will record up to 99 manual measurements and log mode will power the meter on and off to make a measurement every 30 seconds. Every 30 minutes, the meter will average the sixty 30 second measurements and record the averaged value to memory, up to 99 averages. Once full, it will overwrite the oldest measurements with new ones. A daily light integral will be recorded from the 48 averaged measurements for a day’s worth of readings and is downloadable via Apogee AC-100 cable.

MADE IN THE USA – All meters are designed, built, and calibrated at our headquarters in Logan, Utah, USA. Apogee Instruments has been creating research-grade instruments for scientists and serious growers for over 25 years. All meters are backed by our industry leading four-year warranty and supported by our world-class, US-based customer support team.

For a limited time, when purchased on our website from inside the USA, the meter comes with a free AA-090 neoprene protective pouch and free basic shipping.

For instructions on how to use the meter for underwater measurements, see this page for the immersion effect correction factor or consider purchasing the MQ-510.





General Specification



100 g (with 5 m of lead wire)


Meter Dimension : 126 mm length; 70 mm width; 24 mm height
Sensor Dimensions : 24 mm diameter; 37 mm height

Measurement Range

0 to 4000 µmol m-2 s-1

Operating Temperature

0 to 50 C; less than 90 % non-condensing relative humidity up to 30 C; less than 70 % noncondensing relativity humidity from 30 to 50 C; separate sensors can be submerged in water up
to depth of 30 m

Temperature Response

-0.11 ± 0.04 % C-1

Cable Length

2 m of shielded, twisted-pair wire; additional cable available; TPR jacket.

Field Of View


Protection Level