Foot-candle to Lux Conversion Table
| Foot-candle (fc) | Lux (lx) | Reference Benchmark | Formula Step |
|---|---|---|---|
| 0.000093 fc | 0.001 lx | Overcast night sky with starlight only | 0.000093 × 10.764 = 0.001 lx |
| 0.0232 fc | 0.25 lx | Full moon on a clear night at sea level | 0.0232 × 10.764 = 0.25 lx |
| 0.0929 fc | 1 lx | Emergency pathway and exit corridor egress lighting | 0.0929 × 10.764 = 1 lx |
| 0.929 fc | 10 lx | Residential hallway and twilight ambient outdoor light | 0.929 × 10.764 = 10 lx |
| 4.645 fc | 50 lx | Residential living room or cinema auditorium ambient lighting | 4.645 × 10.764 = 50 lx |
| 9.29 fc | 100 lx | Warehouse bulk storage aisles and commercial stairwells | 9.29 × 10.764 = 100 lx |
| 18.581 fc | 200 lx | General dining room and school classroom background light | 18.581 × 10.764 = 200 lx |
| 27.871 fc | 300 lx | Library reading room and hotel conference workspace | 27.871 × 10.764 = 300 lx |
| 46.452 fc | 500 lx | Standard commercial open-plan computer office desktop | 46.452 × 10.764 = 500 lx |
| 69.677 fc | 750 lx | Technical CAD drafting and mechanical inspection bench | 69.677 × 10.764 = 750 lx |
| 92.903 fc | 1000 lx | Precision electronic manufacturing and watchmaking bench | 92.903 × 10.764 = 1,000 lx |
| 185.806 fc | 2000 lx | Hospital operating surgical theater task illumination | 185.806 × 10.764 = 2,000 lx |
| 464.515 fc | 5000 lx | Television broadcasting studio lighting stage | 464.515 × 10.764 = 5,000 lx |
| 929.03 fc | 10000 lx | Overcast overcast midday outdoor daylight | 929.03 × 10.764 = 10,000 lx |
| 2322.576 fc | 25000 lx | Full indirect daylight under clear blue sky | 2,322.576 × 10.764 = 25,000 lx |
| 9290.304 fc | 100000 lx | Direct overhead tropical noon sunlight | 9,290.304 × 10.764 = 100,000 lx |
Foot-candle to Lux Formula & Unit Definitions
The exact ratio derives from the legal definition of the international foot: 1 foot equals 0.3048 meters, which means 1 square foot equals 0.09290304 square meters. When 1 lumen illuminates 1 square foot (1 fc), dividing that luminous flux by 0.09290304 m² gives exactly 1 / 0.09290304 ≈ 10.7639104 lumens per square meter (lux). Consequently, multiplying any foot-candle measurement by 10.7639104 converts it directly to lux.
Quick Estimation: To convert foot-candles to lux in your head, multiply the foot-candle value by 10 and add roughly 7.6% (or multiply by 11 for a quick field estimate). For example, 50 fc multiplied by 10.76 gives approximately 538 lux.
Foot-candle (fc)
Source Unit- Primary US customary illuminance unit defined as 1 lumen per square foot (lm/ft²).
- Mandatory metric across North American building codes, OSHA standards, and IESNA guidelines.
- Represents concentrated illumination where 1 fc provides roughly 10.764 times the density of 1 lux.
Lux (lx)
Target Unit- Coherent International System of Units (SI) derived base unit of illuminance (lm/m²).
- Universal worldwide standard across architectural design, horticulture, and commercial luminaire testing.
- Linear photometric scale where 10.764 lx equals exactly 1 foot-candle of surface brightness.
Frequently Asked Questions
Q.How do you convert foot-candles to lux accurately?
Multiply the illuminance in foot-candles by approximately 10.764 (or 10.7639104). For example, 46.45 fc multiplied by 10.764 yields approximately 500 lx.
Q.What is the exact mathematical ratio between foot-candles and lux?
One foot-candle equals exactly 10.7639104 lux because 1 square meter contains 10.7639104 square feet. Conversely, 1 lux equals 0.09290304 foot-candles.
Q.What is the physical difference between Foot-candle and Lux?
Foot-candle measures luminous flux per square foot (lm/ft²) used primarily in the United States, while Lux measures luminous flux per square meter (lm/m²) used internationally.
Q.How do I convert architectural lighting plans from foot-candles to European lux standards?
Multiply the specified foot-candle values on the US blueprint by 10.764 to verify compliance with European EN 12464 interior lighting standards.