Illuminance measures how much light falls on a surface. Lux is the metric unit; foot-candles are imperial. Proper illumination is critical for workplaces, photography, and plant growth.
What Is Illuminance?
Illuminance = luminous flux per unit area. 1 lux = 1 lumen/m². 1 foot-candle = 1 lumen/ft². Since 1 m² = 10.764 ft², 1 fc = 10.764 lux.
Recommended Light Levels
Office work: 300–500 lux. Reading: 300–500 lux. Kitchen preparation: 500 lux. Hospital operating room: 10,000+ lux. Overcast day: 1,000–2,000 lux. Direct sunlight: 32,000–100,000 lux.
Conversions
- 1 fc = 10.764 lux
- 1 lux = 0.0929 fc
For quick estimates: 1 fc ≈ 10 lux.
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Frequently Asked Questions
How do I convert lux to foot-candles?
Divide lux by 10.764. For example, 500 lux ÷ 10.764 = 46.4 foot-candles.