The SI derived unit for illumination is: lux (lx) = 1 lumen per square meter (lm/m²)
1 flame (flm) = 4 footcandle
1 metercandle (mc) = 1 lumen per square meter (lm/m²) = 1 lux (lx)
1 nox (nox) = 0.001 lux (lx)
1 phot (ph) = 10 000 lux (lx) = 10 000 (lm/m²)
The SI derived unit for luminous flux is: lumen (lm) = 1 candela · steradian (cd·sr)
1 lumen (lm) = 4 · pi (12.566 371 ...) mean spherical candlepower
The SI base unit for luminous intensity is: candela (cd) = 1 lumen per steradian (lm/sr)
1 candle (international) = 1 candela (cd)
1 candela (cd) = 1/1.019 ≈ 0.981 candle power
1 hefner unit (Germany) = 1 / 0.9 candle
1 carcel unit (French) = 9.61 candela (cd)
The SI derived unit for luminance is: candela per square meter(cd / m ²)
1 (cd/m²) = 1 nit (nt) = 0.0001 stilb (sb)= π apostlib (asb)
1 lambert (La) = 10000/π (cd/m²)
1 foot lambert (fLa) = 1/π (cd/ft²)