Convert LED brightness from millicandela (mcd) and viewing angle to lumens. Useful for comparing LEDs beyond just the datasheet mcd number.
💡 Key Insight: mcd is directional brightness, while lumens is total light output. A narrow-beam LED can have high mcd but modest lumens because the light is concentrated into a smaller angle.
🔦 LED mcd, Viewing Angle and Lumens
LED Intensity
Viewing Angle
Quantity Optional
Presets:2,000mcd 30°10,000mcd 15°diffused 120°
Lumens
Viewing Angle
Result
Presets:1lm 30°5lm 60°10lm 120°
mcd Per LED
Viewing Angle
Number of LEDs
Presets:10 LEDs5 bright LEDs20 diffused
📐 Formula Reference
mcd to lumens
cd = mcd / 1000 Ω = 2π × (1 - cos(θ/2)) lm = cd × Ω
lumens to mcd
cd = lm / Ω mcd = cd × 1000 θ = full viewing angle
multiple LEDs
Total lm ≈ lm per LED × qty Assumes beams add together
solid angle
Narrow angle = smaller Ω Wide angle = larger Ω Same mcd can mean different lumens
📋 Quick Reference
🔵 Units
1 cd1000 mcd
mcdintensity
lumenstotal flux
🟢 Typical angles
Indicator LED15–30°
Diffused LED60–120°
Wide LED120°+
🟠 Brightness note
Narrow beamhigh mcd
Wide beammore spread
Compare fairlyuse lumens
📚 Engineering Notes
mcd is not total brightnessMillicandela tells you brightness in a direction. Lumens estimate the total light output over the LED viewing angle.
Viewing angle matters a lotA 10,000 mcd LED at 15° can produce fewer lumens than a lower-mcd LED with a much wider angle.
Datasheet angles varyLED viewing angle is often specified at half intensity. Real beam shape may not be perfectly uniform, so this is a practical estimate.
Complete the LED circuitAfter brightness conversion, use the LED Resistor Calculator to choose a safe current-limiting resistor for your supply voltage.
What is an mcd to Lumens Converter?
An mcd to lumens converter estimates LED luminous flux from millicandela and viewing angle. It is useful because LED datasheets often show brightness in mcd, while users often want to compare LEDs using lumens.
How this helps LED circuit design
When selecting an LED, brightness is only one part of the design. First compare the LED light output using this mcd to lumens converter, then use the CircuitMix LED Resistor Calculator to calculate the series resistor and current for the LED circuit. This creates a simple workflow from LED brightness selection to safe resistor sizing.
Why viewing angle changes the result
The same mcd value can produce different lumen values depending on the beam angle. A narrow-angle LED concentrates light into a small cone, while a wide-angle LED spreads the light over a larger solid angle.
❓ Frequently Asked Questions
They measure different things. mcd is luminous intensity in one direction, while lumens estimate total light output.
Because narrow-beam LEDs concentrate light in one direction. That increases mcd but does not always mean high total light output.
It is a practical estimate using a conical beam approximation. Actual LEDs have non-uniform beam patterns, so datasheet test conditions still matter.