The Lumen-lux conversion calculates the intensity of light hitting or passing through the surface. Type in any two of the measurements and the software will calculate the missing data.

1 lux               Full moon overhead at tropical latitudes
50 lux             Family living room
80 lux             Hallway/toilet
100 lux           Very dark overcast day
320–500 lux  Office lighting
400 lux            Sunrise or sunset on a clear day.

Lumen vs. Lux
The difference between the lux and the lumen is that the lux takes into account the area over which the luminous flux is spread. A flux of 1,000 lumens, concentrated into an area of one square metre, lights up that square metre with an illuminance of 1,000 lux. However, the same 1,000 lumens, spread out over ten square metres, produce a dimmer illuminance of only 100 lux.