# Lux to lumens calculator

Illuminance in lux (lx) to luminous flux in lumens (lm) calculator and how to calculate.

Enter the illuminance in lux (lx), select area unit type, enter radius in meters for spherical light source or surface area

in square meters for any light source and press the *Calculate* button to get the luminous flux in lumens (lm):

## Lux to lumens calculation formula

### Lux to lumens calculation with area in square feet

The luminous flux *Î¦*_{V} in lumens (lm) is equal to 0.09290304 times the illuminance *E*_{v} in
lux (lx) times the surface area *A* in square feet (ft^{2}):

*Î¦*_{V(lm)} = 0.09290304* *Ã—* E*_{v(lx)}* *Ã—* A*_{(ft}2_{)}

For a spherical light source, the area A is equal to 4 times pi times the squared sphere radius:

* A* = 4â‹…Ï€â‹…*r *^{2}

So the luminous flux *Î¦*_{V} in lumens (lm) is equal to 0.09290304 times the illuminance *E*_{v} in
lux (lx) times 4 times pi times the squared sphere radius r in feet (ft):

*Î¦*_{V(lm)} = 0.09290304* *Ã—* E*_{v(lx)}* *Ã—* *4â‹…Ï€â‹…*r*_{(ft)}* *^{2}

So

lumens = 0.09290304* *Ã—*
*lux Ã— (square feet)

or

lm = 0.09290304* *Ã—*
*lx Ã— ft^{2}

### Lux to lumens calculation with area in square meters

The luminous flux *Î¦*_{V}
in lumens (lm) is equal to the illuminance *E*_{v} in
lux (lx) times the surface area *A* in square meters (m^{2}):

*Î¦*_{V(lm)} =
*E*_{v(lx)}* *Ã—*
A*_{(m}2_{)}

For a spherical light source, the area A is equal to 4 times pi times the squared sphere radius:

* A* = 4â‹…Ï€â‹…*r *^{2}

So the luminous flux *Î¦*_{V}
in lumens (lm) is equal to the illuminance *E*_{v} in lux (lx) times 4 times pi times the squared sphere radius r in meters (m):

*Î¦*_{V(lm)} = *E*_{v(lx)}* *Ã— 4â‹…Ï€â‹…*r *^{2}

So

lumens = lux Ã— (square meters)

or

lm = lx Ã— m^{2}

##### Example

What is the luminous flux on a surface of 4 square meters and illuminance of 500 lux?

*Î¦*_{V(lm)} = 500 lux Ã— 4 m^{2} = 2000 lm