Convert luminous flux in lumens (lm) to luminous intensity in millicandela (mcd) using beam angle.
Formula:
Steradians (sr) = 2 × π × (1 - cos(θ / 2))Candela (cd) = Lumens / srMillicandela (mcd) = cd × 1000Welcome to the Lumens to Millicandela Calculator – your go-to tool for converting luminous flux (lumens) into light intensity (millicandelas). This calculator is especially useful in engineering, product design, LED lighting analysis, automotive electronics, and optical system development, where small-scale precision matters. Understanding the difference between lumens and millicandelas allows for more accurate design and testing of directional light sources such as LEDs, laser diodes, and signal lights.
Lumens (lm) are a unit of luminous flux, representing the total amount of visible light emitted by a light source. It measures the overall brightness, regardless of direction. When you read a product specification like "300 lumens," it refers to the total visible light output in all directions.
Millicandela (mcd) is a unit of luminous intensity. It measures how bright the light appears in a specific direction. One candela (cd) equals 1000 millicandela (mcd). Unlike lumens, which consider the total output, millicandela is ideal for measuring how focused a light is.
This makes millicandela a crucial metric for evaluating LEDs, spotlights, flashlights, and small directional light sources like indicators and remote control IR diodes.
The relationship between lumens and millicandelas depends on the beam angle. Here's the formula to convert lumens to candela first:
cd = lumens / (2π × (1 - cos(θ / 2)))Then, multiply the result by 1000 to convert to millicandela:
mcd = cd × 1000Let’s say you have a 2-lumen LED with a beam angle of 20°:
cd = 2 / (2π × (1 - cos(10°))) ≈ 2 / 0.095 ≈ 21.05 cdNow, convert to millicandela:
mcd = 21.05 × 1000 = 21,050 mcdThis means that even a 2-lumen LED can have over 20,000 mcd if its beam is very narrow, which is common in status indicators or laser applications.
Understanding and converting lumens to millicandela is important because:
When building custom lighting circuits, engineers need to know the directional intensity (mcd) for current-limiting resistors and brightness optimization.
Tail lights, dashboard indicators, and cockpit signaling use directional LEDs rated in millicandela to ensure visibility under sunlight or harsh conditions.
Remote controls and IR sensors operate using highly focused beams. The mcd rating helps manufacturers understand how intense the beam will appear over long distances.
A flashlight with high lumens but a wide beam may seem less bright than a low-lumen flashlight with a narrow, high-mcd beam. This is critical for tactical and professional lighting tools.
Suppose you're designing a device with a visual indicator and need it to be visible in daylight. You find two LEDs:
Using the calculator, you’ll often find that LED B has a higher mcd rating due to its focused beam. Hence, it will appear brighter to the eye from a distance, even though it has fewer lumens.
Our calculator is based on industry-standard formulas used in photometry. However, real-world results can vary slightly due to:
For precise applications, it's recommended to use manufacturer-provided IES files or perform lab testing with a goniophotometer.
Below is a quick comparison of how beam angle affects candela and millicandela values from a 1-lumen source:
| Beam Angle (°) | Approx. Candela | Approx. Millicandela |
|---|---|---|
| 10° | 17.58 | 17,580 |
| 20° | 8.79 | 8,790 |
| 40° | 3.17 | 3,170 |
| 60° | 1.67 | 1,670 |
| 120° | 0.46 | 460 |
This shows that even low-lumen LEDs can achieve high mcd values if they are narrowly focused.
The only difference is the unit scale. 1 candela = 1000 millicandela. Use millicandela when dealing with small, precise light sources like LEDs. Use candela when working with large-scale lighting fixtures such as projectors, car headlights, or searchlights.
The Lumens to Millicandela Calculator is an indispensable tool for engineers, developers, and hobbyists working with precision lighting. It helps you evaluate brightness, directional focus, and visibility with clarity. Whether you're designing LED circuits, testing a new flashlight, or developing a lighting product, this calculator ensures your design meets real-world expectations for light performance.
Use our tool to convert with confidence and make smarter lighting decisions today!
Let’s explore specific real-world applications where converting lumens to millicandela is not just helpful, but necessary for compliance, performance, or safety.
Devices like smartphones, fitness trackers, and remote controllers often use small indicator LEDs. While these lights are low in total lumens, their visibility depends heavily on beam focus—measured in millicandela. Product designers use our conversion method to ensure indicators remain visible in daylight or at specific angles, without overdraining the battery.
In life safety systems such as fire alarms and evacuation path indicators, light visibility over a distance is critical. Authorities such as the NFPA (National Fire Protection Association) and OSHA define minimum luminous intensity in terms of candela or millicandela for strobe lights and exit signs. Using a lumens-to-mcd calculator helps you meet such life-saving criteria.
Modern drones use position and navigation LEDs for visibility and collision avoidance. For night flying or long-range operation, high-mcd directional LEDs are preferred. Even with minimal lumen output, high mcd values ensure the drone is visible to pilots and air traffic controllers from hundreds of meters away.
In applications like facial recognition, IR sensors, or security cameras, the brightness of infrared LEDs is defined using candela or millicandela rather than lumens, as IR light is not visible. Conversion tools help developers evaluate infrared LED specs for better performance in night-vision and thermal optics systems.
It’s a common misconception that a light with more lumens is “brighter.” In truth, perceived brightness depends on focus and application:
This is why designers use both lumen and mcd ratings to balance spread and intensity depending on the intended task.
Even without changing the lumen value of an LED, its millicandela output can be increased using optical engineering:
By modeling these systems using known lumen outputs, designers can calculate and verify the resulting mcd using this calculator.
In regulated industries, minimum visibility standards are enforced through luminous intensity, often defined in mcd. Some examples include:
In these situations, incorrect assumptions about lumens could lead to legal non-compliance. Always verify using accurate mcd calculations.
Many datasheets don’t provide candela or millicandela values directly. Instead, they list lumens and beam angle. Without proper tools, engineers may make incorrect assumptions:
Using a lumens to mcd calculator ensures precision without requiring physical light testing in the early design stages.
Retailers and eCommerce sellers can benefit from adding millicandela ratings to their LED product listings. While many consumers know to look for "lumens," mcd provides another layer of insight, especially for:
The-wise, including mcd specs may also improve product visibility in niche searches like “brightest red LED 5mm 6000 mcd.”
Yes, but you’ll also need the beam angle. The reverse formula is:
lumens = (mcd / 1000) × 2π × (1 - cos(θ / 2))No. Millicandela measures intensity in a direction, while lux measures illumination on a surface. Both are derived from lumens but serve different applications.
Yes, depending on the lens, reflector, or beam angle used. The same LED die may have vastly different mcd ratings based on optical configuration.
Not necessarily. It depends on the application. A diffuse reading light benefits from lower mcd and higher spread, while a status indicator or beam LED benefits from high mcd.
Whether you're a lighting engineer, product designer, DIY hobbyist, or student, this Lumens to Millicandela Calculator will streamline your workflow and enhance your accuracy. It ensures you’re not just choosing the “brightest” LED but the right one for your use case.
Pair this calculator with beam angle charts, optical testing, and photometric data to design truly efficient and purpose-built lighting systems. Remember, brightness is not just how much light you produce—it’s where and how you focus it.
Try the calculator now and bring clarity to your lighting designs, one beam at a time.