Foot-candles to PPFD converter

Enter a foot-candle reading and pick your light source. The converter first turns foot-candles into lux (× 10.764), then divides by a typical lux-to-PPFD factor for that spectrum. Treat the result as a rough estimate, not a calibrated measurement.

Steps: lux = foot-candles × 10.764, then PPFD ≈ lux ÷ source factor.

FAQ

How do you convert foot-candles to PPFD?

First convert foot-candles to lux by multiplying by 10.764. Then divide the lux value by a source-specific factor to estimate PPFD, because lux is weighted for the human eye rather than for photosynthesis.

Is a foot-candles-to-PPFD conversion accurate?

It is only a rough estimate. The lux-to-PPFD step depends on the exact spectrum of the light, which a single factor cannot capture, and light-meter apps vary between phones. For readings that matter, use a calibrated quantum sensor.

The foot-candles-to-lux step (× 10.764) is an exact unit conversion. The lux-to-PPFD step is not: it depends on the light spectrum and can be off by a wide margin for any given fixture. Sunlight (54), HPS (77) and metal halide (71) come from Apogee Instruments' published table; Apogee publishes no white-LED factor, so the 67 here is a commonly cited approximation and the least reliable of the four. A lux or foot-candle estimate cannot replace a quantum sensor.