Manufacturers of LEDs and bulbs usually provide the luminous intensity of their products in lumens, candelas (cd) or millicandelas (mcd). For **from lumens to millicandelas** or vice versa, we have developed a pair of very simple converters that take into account the aperture angle of the light source.

It is important for you to know this last piece of information because, depending on it, the **luminous intensity in millicandelas or lumens** can vary quite a bit.

## How to go from Lumens to millicandelas

For **convert from lumens to millicandelas** manually you have to use this formula:

I_{v(mcd)}= 1000 ×Φ_{v(lm)}/ ( 2π(1 - cos(θ/2)) )

There are three variables in it, which are:

*I*_{v(mcd)}light intensity in millicandelas*Φ*_{v(lm)}luminous flux in lumens*θ:*the opening angle in degrees

If you have the aperture angle in steradians, the formula to convert lm to mcd is this:

I_{v(mcd)}= 1000 ×Φ_{v(lm)}/Ω_{(sr)}

In the next section we will show you how to convert the opening angle in steradians to degrees.

## How to go from Milicandelas to lumens

Millicandelas is a unit of luminous intensity widely used in LEDs and other light sources, so it is likely that at some point you will find yourself with the need to know the **equivalence between millicandelas (mcd) and lumens (lm).**

Thanks to our **online calculator** you will be able to work with these two units, but if you want to know how to change from mcd to lm, you just have to apply the following mathematical formula:

Φ_{v(lm)}=I_{v(mcd)}×Ω_{(sr)}/ 1000

Being:

*Φ*_{v(lm)}The luminous flux.*I*_{v}The luminous intensity in millicandels*Ω*_{(sr)}The opening angle in steradians.

The **angle in steradians** is equal to twice PI times 1 minus the cosine of half of the opening angle in degrees. That is, what the following formula shows:

Ω_{(sr)}= 2π(1 - cos(θ/2))

If we substitute in the initial formula for **convert from millicandelas to lumens** we are left with:

lumens =

I_{v(mcd)}× (2π(1 - cos(degrees/2)) ) / 1000

If you have any questions regarding these two units used to measure light intensities, leave us a comment and we will help you as soon as possible.