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Lumens to Candela Calculator

Convert luminous flux (lumens) and apex angle back to luminous intensity (candela).

Input Data

Input Luminous flux Φ.
lm
Input Apex angle θ.
°

Results

318.309886cd
I = Φ / Ω = 1000 lm / 3.141593 sr = 318.309886 cd

At a glance:Lumens to Candela Calculator: enter parameters to compute results; complements related calculators.

Formula

I = Φ / Ω

Ω = 2π(1 − cos(θ/2)), θ = apex angle (degrees)

Φ: luminous flux (lm), I: luminous intensity (cd)

How to Use

  1. Enter luminous flux Φ (lumens).
  2. Enter apex angle θ (full angle, degrees).
  3. Get luminous intensity I (candela).

Case Studies

6.283 lm, apex 180°

Ω = 2π sr ≈ 6.283 sr, I = 6.283 / 6.283 = 1 cd.

FAQ

Why the apex angle?

Luminous intensity is flux per solid angle, so the covered solid angle is required.

Isotropic source?

At θ = 360°, Ω = 4π and I = Φ/(4π).

Related Tools

References

Content review: Calculatorism Science Team. Formula and numeric tests verified; results for reference only.

Found a problem with the results?

If this calculator's result is wrong, or you have any question about the calculation logic, please let us know. You are viewing:Lumens to Candela Calculator（/light/lumens-to-candela）。