lighting lux level stantards

1 lx = 1 lm·m-2 = 1 cd·sr·m–2.

As with other SI units, SI prefixes can be used, for example a kilolux (klx) is 1,000 lux.

Illuminance Example

10-5 lux Light from Sirius, the brightest star in the night sky[2]

10-4 lux Total starlight, overcast sky[2]

0.002 lux Moonless clear night sky with airglow[2]

0.01 lux Quarter moon

0.2 lux Design minimum for emergency lighting (AS2293).

0.27 lux Full moon on a clear night[2][3]

1 lux Full moon overhead at tropical latitudes[4]

3.4 lux Dark limit of civil twilight under a clear sky[5]

50 lux Family living room[6]

80 lux Hallway/toilet[7]

100 lux Very dark overcast day[2]

320 lux Recommended office lighting (Australia)[8]

400 lux Sunrise or sunset on a clear day. Well-lit office area.

500 lux Lighting level for an office according to the European law UNI EN12464.

1,000 lux Overcast day[2]; typical TV studio lighting.

10,000–25,000 lux Full daylight (not direct sun)[2]

32,000–130,000 lux Direct sunlight Unicode has a symbol for "lx":

(㏓), but this is just a legacy code to accommodate old code pages in certain Asian languages, and it is not recommended for use in any language today.

Lux versus lumen

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, produces a dimmer illuminance of only 100 lux.

Achieving an illuminance of 500 lux might be possible in a home kitchen with a single fluorescent light fixture with an output of 12,000 lumens. To light a factory floor with dozens of times the area of the kitchen would require dozens of such fixtures. Thus, lighting a larger area to the same level of lux requires a greater number of lumens.