Foot-Candle
unit of energy measurement
Definition of Foot-Candle
Foot-candle (fc) is a unit of measurement that describes the amount of light reaching a certain point in a specific area. It is the amount of light that falls on a one-square-foot area located one foot away from a light source.
Lumen is the foundational unit, measuring the quantity of light produced by a light fixture.
Foot-candle measurements can be affected by:
- Distance between the lit surface and the light source
- Angle of the light beam
- Height of the light source
- Reflectance of the surface
- Presence of any obstructions or shadows.
Foot-candles are an important measurement to consider when determining the amount of light needed to illuminate a particular space safely and efficiently.
Here is a comparison between various lux and foot-candle thresholds and the types of spaces they suit.
| Light Level (Foot Candles) | Light Level (Lux) | Suitable Type Of Space |
| 10–30 fc | 100–300 lux |
|
| 5–10 fc | 50–100 lux |
|
| 20–30 fc | 200–300 lux |
|
| 30–50 fc | 300–500 lux |
|
| 75–120 fc | 750–1200 lux | Laboratory |
Example of Foot-Candle in a Sentence
"The navigation lights on my boat need to produce at least 2.5 foot-candles of light to meet the safety requirements set by the Coast Guard."
Synonyms: lumen per square foot, lux
Related Terms for Foot-Candle