Footcandle (fc) is a unit of illuminance , which indicates how much light a surface receives. 1 footcandle = 1 lumen per square foot (1 lm/ft²).
It is widely used in architecture, photography, interior lighting and theatrical lighting to determine the amount of light required.
Formula and conversion
- Lumen (lm) = total light output of a light source.
- Footcandle (fc) = how much light falls on a surface.
- Lux (lx) = metric unit for illuminance ( 1 lux = 1 lumen per square meter ).
Convert:
How many footcandles do you need?
The required illuminance depends on the application:
| Application | Footcandles (fc) | Lux (lx) |
|---|---|---|
| Living room | 5-20 fc | 50-200 lx |
| Office work | 30-50 fc | 300-500 lx |
| Supermarket | 50-100 fc | 500-1000 lx |
| Operating room | 100-200 fc | 1000-2000 lx |
| Photo studio | 100-500 fc | 1000-5000 lx |
Why is footcandle important?
✅ Determines the right lighting for work spaces (e.g. offices, factories, classrooms).
✅ Used in lighting design and energy saving (e.g. LED planning).
✅ Necessary for photography and film to correctly adjust exposure.