Orders of magnitude (illuminance)

As visual perception varies logarithmically, it is helpful to have an appreciation of both illuminance and luminance by orders of magnitude.

Illuminance

To help compare different orders of magnitude, the following list describes various source in lux, which is a lumen per square metre.

Factor (lux)	Multiple	Value	Item
0	0 lux	0 lux	Absolute darkness
10−4	100 microlux	100 microlux	Starlight overcast moonless night sky[1]
		140 microlux	Venus at brightest[1]
		200 microlux	Starlight clear moonless night sky excluding airglow[1]
10−3	1 millilux	2 millilux	Starlight clear moonless night sky including airglow[1]
10−2	1 centilux	1 centilux	Quarter Moon
10−1	1 decilux	2.5 decilux	Full Moon on a clear night[1][2][3]
100	1 lux	< 1 lux	Extreme of darkest storm clouds, sunset or sunrise
101	1 decalux	40 lux	Fully overcast, sunset or sunrise
102	1 hectolux	< 200 lux	Extreme of darkest storm clouds, midday
		400 lux	Sunrise or sunset on a clear day (ambient illumination)
104	10 kilolux	10–25 kilolux	Typical overcast day, midday
		20 kilolux	Shade illuminated by entire clear blue sky, midday
105	100 kilolux	110 kilolux	Bright sunlight
		120 kilolux	Brightest sunlight

Luminance

This section lists examples of luminances, measured in candelas per square metre and grouped by order of magnitude.

Factor (cd/m2)	Multiple	Value	Item
10−6	μcd/m2	1 μcd/m2	Absolute threshold of vision[4]
10−5
10−4
10−3	mcd/m2	100 μcd/m2	Cloudy night sky without moon[4]
		400 μcd/m2	"Darkest sky"[5]
		1 mcd/m2	Night sky[6]
		1.4 mcd/m2	Typical photographic scene lit by full moon[7]
10−2		5 mcd/m2	Approximate scotopic/mesopic threshold[8]
10−1
100	cd/m2	2 cd/m2	Floodlit buildings, monuments, and fountains[9]
101		5 cd/m2	Approximate mesopic/photopic threshold[8]
		25 cd/m2	Typical photographic scene at sunrise or sunset[7]
		30 cd/m2	Green electroluminescent source[5]
102		55 cd/m2	Standard SMPTE cinema screen luminance[10]
		80 cd/m2	Monitor white in the sRGB reference viewing environment
		250 cd/m2	Peak luminance of a typical LCD monitor[11][12]
		700 cd/m2	Typical photographic scene on overcast day[7][9][12]
103	kcd/m2	1 kcd/m2	Cloudy sky at noon[4][12]
		2 kcd/m2	Average cloudy sky[5][12]
		2.5 kcd/m2	Moon surface[5][6]
		3–5 kcd/m2	Clear sky[6][12]
104		5 kcd/m2	Typical photographic scene in full sunlight[7][9]
		8 kcd/m2	Average clear sky[5][12]
		10 kcd/m2	Clear sky at noon[4][12]
		10 kcd/m2	White illuminated cloud[6]
		12 kcd/m2	Fluorescent lamp[5][6]
105		75 kcd/m2	Low pressure sodium-vapor lamp[6]
		130 kcd/m2	Frosted incandescent light bulb[5][6][12]
106	Mcd/m2	600 kcd/m2	Solar disk at horizon[5]
107		7 Mcd/m2	Filament of a clear incandescent lamp[13]
108		100 Mcd/m2	Possible retinal damage[4]
109	Gcd/m2	1.6 Gcd/m2	Solar disk at noon[5][6]

See also

• Photometry (optics)
• Extraterrestrial sky