Foot Candle

A measure of illuminance in imperial units — one lumen per square foot. Commonly used in US building codes and lighting design.

Foot candles are the American equivalent of lux — they measure how much light lands on a surface, but in lumens per square foot instead of lumens per square meter. One foot candle equals approximately 10.76 lux.

You'll encounter foot candles primarily in US building codes, IES (Illuminating Engineering Society) guidelines, and commercial lighting design. Residential electricians and lighting designers in the US still specify rooms in foot candles: 10-20 fc for a hallway, 30-50 fc for an office, 50-75 fc for a kitchen counter.

For most homeowners, converting between foot candles and lux isn't necessary — just know that if a guide says "30 foot candles" and your lux meter reads 300 lux, you're in the same ballpark.

Specifications

1 foot candle	≈ 10.76 lux
30 fc	Typical office lighting
50 fc	Retail / detailed work

Related Terms

Lux
A measure of illuminance — how many lumens hit one square meter of surface. Used to specify lighting levels for rooms and workspaces.
Lumens
The unit measuring total visible light output. Unlike watts, lumens tell you how bright a bulb actually is.

Mentioned in

LED Lighting

What Is A Foot Candle Measurement?

Double the distance between a bulb and a surface, and illuminance drops to one-quarter — not one-half. That gap between lumens (what the bulb produces) and foot-candles (what actually lands on your desk) is why brighter bulbs don't always fix dim rooms.