About the Millicandela to Lumens Calculator
An LED rated at 15,000 mcd sounds very bright, but if its beam is only 20° wide it gives out less than one and a half lumens. This calculator turns a millicandela rating into total light in lumens by multiplying the intensity by the solid angle of the beam. Type the mcd and the viewing angle from the datasheet to get the lumens, candela and steradians, and compare indicator LEDs fairly with bulbs and torches rated in lumens.
Updated October 2026
How to use the Millicandela to Lumens Calculator
- 1Enter the luminous intensity in millicandela.
- 2Enter the full viewing angle in degrees.
- 3Read the total light output in lumens.
- 4Check the candela and solid angle rows.
- 5Copy the result.
Intensity versus total light
Millicandela describes how bright a light looks when you stand in its beam. Lumens describe all the light it emits in every direction. A laser pointer has enormous intensity but very few lumens; a frosted bulb has many lumens but modest intensity in any one direction. The viewing angle connects the two.
Formula and quick figures
The solid angle of a cone with full angle θ is Ω = 2π(1 − cos(θ/2)). Lumens = candela × Ω, and candela = mcd ÷ 1,000.
- 1,000 mcd at 15°: about 0.054 lm
- 1,000 mcd at 30°: about 0.21 lm
- 1,000 mcd at 60°: about 0.84 lm
- 1,000 mcd at 120°: about 3.14 lm
Using the result
Lumens let you add up several LEDs and compare the total with a lamp, or work out lux on a surface by dividing lumens by the area. For a backlight using ten 5,000 mcd LEDs at 60°, the total is about 42 lm; spread over a 0.05 m² panel that is about 840 lux before losses.
Common datasheet traps
Some sellers quote mcd for the very narrowest version of an LED, or at a higher current than you plan to use. Use the angle and current that match the part you are buying. Coloured LEDs also have different lumen ratings because the eye is most sensitive to green, so a green LED usually shows a higher mcd than a blue one with the same power.
From lumens to lux
Once you have lumens, you can estimate how bright a surface will be. Divide the lumens by the area the beam covers in square metres to get lux. A 1.4 lm LED lighting a 10 cm circle (about 0.0079 m²) gives roughly 180 lux on that spot, enough to read by, while the same LED spread over a whole desk gives almost nothing. That is why narrow-beam LEDs are used for indicators and wide ones for lighting.
On your phone
Look up an LED's datasheet on your phone and convert its rating on the spot; the page needs no app and no sign-up. Beam angle and brightness go together, so keep both in mind. Reverse the calculation with the Lumens to Millicandela Calculator, use the Candela to Lumens Calculator for larger values, and compare a bulb with the Lumens to Watts Calculator.
Features
- mcd to lumens and candela
- Viewing-angle based
- Solid angle shown in steradians
- Works with any angle up to 360°
- One-tap copy
- Private, nothing uploaded
Frequently asked questions
How do I convert mcd to lumens?
Lumens = mcd ÷ 1,000 × 2π × (1 − cos(angle ÷ 2)). A 15,000 mcd LED with a 20° angle gives about 1.43 lm.
How many lumens is 1,000 mcd?
It depends on the angle: about 0.21 lm at 30°, 0.84 lm at 60° and 3.14 lm at 120°.
Why is the lumen figure so small?
Indicator LEDs focus a little light into a narrow beam. The high mcd number describes the beam's centre, not the total amount of light.
Which angle should I enter?
The full viewing angle, often labelled 2θ½ on the datasheet, where the brightness drops to half.
Is the answer exact?
It assumes even light across the cone. Real LEDs fade towards the edge, so the true lumens are usually a little lower than this estimate.
Can I compare an LED with a bulb using this?
Yes. Bulbs and torches are sold by lumens, so converting the LED's mcd gives you a like-for-like figure.