Illuminance Converter Free Online
Convert illuminance — luminous flux per area — between lux (SI lumen/m²), foot-candle (lumen/ft²), phot (lumen/cm²), and nox. Office lighting ≈ 500 lux ≈ 46 fc.
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Illuminance Converter Features
Lighting Design
Office desk: 500 lux. Detailed work: 1000+ lux. Living room: 100–300 lux. Outdoor full sun: 100,000 lux. Moonlight: 0.1 lux.
6 Units
SI lux and lm/m² (identical), US foot-candle and lm/ft² (identical), CGS phot, and twilight nox. Switch between US lighting plans (fc) and SI specs (lux).
SI & Imperial
1 fc = 10.764 lux exactly (since 1 m² = 10.764 ft²). 50 fc = 538 lux — typical office. Home plans often use fc; commercial plans use lux.
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Free vs Pro
| Feature | Free | Pro |
|---|---|---|
| Full illuminance conversion | ||
| Live conversion | ||
| All-units result panel | ||
| Bulk CSV / Excel conversion | — | |
| REST API access | — | |
| Custom precision settings | — |
Frequently Asked Questions
1 fc = 10.7639 lux. Equivalently 1 lux ≈ 0.0929 fc. The conversion comes from 1 m² = 10.7639 ft², so the same lumens spread over 1 m² (lux) are 10.764× thinner than over 1 ft² (fc).
OSHA recommends 500 lux (46 fc) for general office tasks. CAD / detailed drafting: 1000 lux (93 fc). Conference rooms: 300 lux. Hallways: 100 lux.
Lumens measure total light output of a source. Lux measures how much falls on a surface per m². A 1000-lumen bulb illuminating 10 m² gives 100 lux on average. Distance and beam spread matter.
Direct summer sunlight: ~100,000 lux. Overcast day: ~10,000 lux. Sunrise/sunset: ~400 lux. Full moon: ~0.25 lux. Starlight only: ~0.001 lux.
CGS unit = lumen / cm² = 10,000 lux. Used in older optics texts. 1 milliphot = 10 lux. Modern lighting design uses lux or foot-candle exclusively.