Calculators

Lighting calculators

12 tools

Lumens, lux, candela, and lighting conversions.

Candela to Lumen Calculator Convert candela (cd) to lumens (lm) using beam angle: lm = cd × 2π(1 − cos(θ/2)). Reverse lumens to candela. Includes solid angle and full-sphere 4π.
Candela to Lux Calculator Convert luminous intensity in candela to illuminance in lux at a given distance (inverse-square). Runs locally in your browser. Try it free.
Foot-Candles to Lux Calculator Convert foot-candles (fc) to lux (lx): lx = fc × 10.76391. Free online tool — no sign-up. Clear formulas and worked examples. Runs locally in your browser.
Lumen to Candela Calculator Convert lumens (lm) to candela (cd) using beam angle: cd = lm ÷ 2π(1 − cos(θ/2)). Reverse candela to lumens. Includes solid angle and full-sphere 4π.
Lumen to Lux Calculator Convert lumens (lm) to lux (lx): lx = lm ÷ A. Use area in m² or ft², or isotropic sphere radius. Reverse lux to lumens. Runs locally in your browser.
Lumen to Millicandela Calculator Convert lumens (lm) to millicandela (mcd): mcd = 1000 × lm ÷ 2π(1 − cos(θ/2)). Reverse mcd to lumens. Runs locally in your browser. Fast and free.
Lumen to Watt Calculator Convert lumens (lm) to watts (W) using luminous efficacy: W = lm ÷ η (lm/W). Reverse watts to lumens. Includes typical LED, CFL, halogen, and incandescent.
Lux to Candela Calculator Convert lux (lx) to candela (cd) at a distance: cd = lx × d² (meters) or cd = lx × d(ft)² ÷ 10.76391. Reverse candela to lux. Runs locally in your browser.
Lux to Lumen Calculator Convert lux (lx) to lumens (lm): lm = lx × A. Use area in m² or ft², or isotropic sphere radius. Reverse lumens to lux. Runs locally in your browser.
Lux to Watt Calculator Convert lux (lx) to watts (W): W = (lx × A) ÷ η. Free online tool — no sign-up. Clear formulas and worked examples. Runs locally in your browser.
Watt to Lumen Calculator Convert watts (W) to lumens (lm): lm = W × η (lm/W). Free online tool — no sign-up. Clear formulas and worked examples. Runs locally in your browser.
Watt to Lux Calculator Convert watts (W) to lux (lx): lx = (W × η) ÷ A. Free online tool — no sign-up. Clear formulas and worked examples. Runs locally in your browser.