How bright is it? Light levels from night to noon.
Light is measured in lux. A lit room at night is a few tens to a few hundred lux, an office a few hundred, and full sun tens of thousands. Your eyes cross that whole range every day.
What lux measures.
Lux is the unit of illuminance: how much light falls on a surface. One lux is one lumen spread over one square metre.
At night.
A full moon on a clear night gives about 0.05 to 0.3 lux. A moonless, overcast night gives about 0.0001 lux.
In a small study for the United States Department of Energy, 30 lighting professionals measured the light reaching their eyes at home in the evening. In the living room the middle value was 23 lux, and the highest 410. In the kitchen, with all the lights on, the middle value was 104 lux, and the highest 485. Reading in bed, the middle value was 15 lux.
By day.
Office lighting is about 320 to 500 lux. An overcast day outside is about 1,000 lux. Shade on a sunny day is about 10,000 to 20,000 lux. Direct sunlight is about 32,000 to 100,000 lux.
Your eyes adjust, slowly.
The eye works from very dark to very bright light, but it needs time. Going from bright sun into full darkness, it takes about 20 to 30 minutes to adjust fully. Going from darkness into bright sun takes about five minutes.
One day of light.
Your level
Bedroom at night
Living room
Office
Cloudy day
Shade on a sunny day
Full sun
Your level
The light levels are typical values. The second line shows the aim, not a test result.
| Place | Typical lux |
|---|---|
| Bedroom at night | 15 |
| Living room | 50 |
| Office | 320 to 500 |
| Cloudy day | 1,000 |
| Shade on a sunny day | 10,000 to 20,000 |
| Full sun | 32,000 to 100,000 |
Sources
- Home nighttime light exposures, Pacific Northwest National Laboratory for the United States Department of Energy: bedroom at night.
- Lux, Wikipedia: living room, office, cloudy day and full sun.
- Light meters, Glance at the Dance of Photons, University of Prince Edward Island: living room.
- Illuminance, Wikipedia: shade on a sunny day.
- Daylight, Wikipedia: shade on a sunny day.
Sources:
- Wikipedia: Lux
- Pacific Northwest National Laboratory for the United States Department of Energy: Home Nighttime Light Exposures
- Wikipedia: Illuminance
- Wikipedia: Daylight
- Wikipedia: Adaptation (eye)
Other guides
Where Photenic fits.
Photenic is being made for this gap: a tint you set, on the glasses you already own. It is in development.