Photosynthetically active radiation (PAR), Lumen, and Radiant Flux conversion Calculator

This calculates lighting as it is relevant between plants and humans using actual spectrum curves. This should be accurate for LED based grow lights as well as any other type of lighting as long as the spectrum is known. The lumen and PAR dependent numbers are calculated based on actual studies that measured the real world curves. The PAR curve is from Institute of Life Science and Biology Department, Texas A and M University, College Station, Texas (U.S.A.), the lumen curve is from Stockman & Sharpe cone fundamentals

Light Properties

Note: In this calculator radiant flux is calculated only over displayed wavelengths of 375-800nm. The Black Body Spectrum input clips the spectrum to be within 400-700nm. When using the black body spectrums the radiant flux is measured only over the 400-700nm range.

Radiant Flux is a measure of actual light output, and here it is a measure of actual light output over the given spectrum. When entering radiant flux, a rough estimate is .
Black Body Spectrum is in degrees kelvin, assumes the light source is an ideal black body radiator clipped to 400-700nm
Single/Custom Wavelength accepts a comma deliminated list of wavelengths in nm and relative weights. Example "500" means a single monochromatic light at 500nm, "500, 400, 700" means a light source with power equally distrubuted through the three wavelengths, 400nm, 500nm, and 700nm. "400:2, 700:1" means 2/3 of the power is at 400nm and 1/3 of the power is at 700nm.

Fixture Properties

Fixture style:
Beam width: degrees (beam width is the angle between that the light spreads out from the fixture, a bulb without a fixture will usually be 360 degrees, it is also know as the beam angle)
Height: (Height is measured from the filament or the point behind the bulb where the beam converges to a point for LEDs)
Length: (Only applies to rectangular fixtures)

Timer Properties

Hours on per day (photoperiod): Hours


Area Illuminated by light at the given distance:

Total Light output:

Radiant Flux: W
PPF: μmol/s
PAR Watts: W
Lumens: lm

Intensity at distance

Radiant Flux Density: W/m^2
PPFD: μmol/s*m^2
PAR Irradiance: W/m^2
Lux: lux
Daily Light Integral (DLI) mol/day
Proper lighting for a plant is primarly determined by the DLI, with seasonal variation acheived through varying the photoperiod. The DLI requirements for select plants can be found in this study Measuring Daily Light Integral in a Greenhouse. 5mol/day is acceptable for some plants, most will grow well with 10mol/day, and pratically all high light plants will find 20+mol/day excellent