Candela to Lumens Calculator
Convert luminous intensity (candela) and apex angle to luminous flux (lumens).
Input Data
Input Luminous intensity I.
cd
Input Apex angle θ.
°
Results
3,141.592654lm
Φ = I × Ω = 1000 cd × 3.141593 sr = 3141.592654 lm
At a glance:Candela to Lumens Calculator: enter parameters to compute results; complements related calculators.
Formula
Φ = I × Ω
Ω = 2π(1 − cos(θ/2)), θ = apex angle (degrees)
I: luminous intensity (cd), Φ: luminous flux (lm)
How to Use
- Enter luminous intensity I (candela).
- Enter apex angle θ (full angle, degrees).
- Get luminous flux Φ (lumens).
Case Studies
1 cd, apex 180°
Ω = 2π(1−cos90°) = 2π sr ≈ 6.283 sr, Φ = 1 × 6.283 ≈ 6.283 lm.
FAQ
What is the apex angle?
The full beam angle of the source; 360° means isotropic emission, Ω = 4π sr.
Relation to illuminance?
Divide luminous flux by area to get illuminance (lux).
Related Tools
References
Content review: Calculatorism Science Team. Formula and numeric tests verified; results for reference only.