Table I. Approximate illuminance ranges of different lighting environments (measured on a horizontal plane). Illuminance indicates the flux density of a light source and is measured in lux (symbol: Ix). Lux is defined as lumen per unit area (lumen per square meter: 1 lx=lm/m2). Please note that in most cases, where the light source is located above a human observer, much less illuminance is measured on a vertical plane at the approximate eye level (viewing direction).
| Environmental lighting situation | Typical illuminance range [lx] |
| Daylight, clear sky | 50 000-100 000 |
| Daylight, overcast sky | 10 000-20 000 |
| Light therapy lamp | 5000-10 000 |
| Precise indoor workbench | 1000-2000 |
| Typical indoor office setting | 300-500 |
| Living room lighting | 50-200 |
| Street and walkway lighting | 5-20 |
| Full moonlight | <1 |