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PAR Flux Calculator

One of the big challenges with growing food indoors is that plants need a lot of light. I made this calculator to help with figuring out how much artificial light is enough. As an example, according to what I've read from Cornell's research, 15 to 17 mol/m²/d is the ideal daily light integral for lettuce.

Solve for PAR flux

To get a daily light integral of mol/m²/d when you run lights for hours a day, you need to measure a PAR flux of μmol/m²/s with your quantum meter at plant height.


Photosynthetically Active Radiation (PAR) is light in the spectrum that plants can use for photosynthesis—photons with wavelengths of 400 to 700 nanometers.

PAR flux is the amount of PAR that lands on a unit of area during a unit of time. PAR flux is often measured in moles per square meter per day (mol/m²/d) or micro-moles per square meter per second (μmol/m²/s).

Photosynthetic Photon Flux Density (PPFD) is another name for PAR flux. PPFD is often measured in μmol/m²/s.

Daily Light Integral (DLI) is the amount of PAR that a unit of area receives in a day. DLI is often measured in mol/m²/d.

Quantum meter is the name for a device that measures PPFD and potentially also DLI.

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