Convert Phots to Foot-candles
Convert Phots (ph) to Foot-candles (fc) instantly and accurately.
Conversion Formula
fc = ph × 929.0304
About Phots
The phot (ph) equals 1 lm/cm² = 10 000 lx. The CGS-photometric unit of illuminance. Pre-SI optics texts express daylight in phots: full tropical sunshine is ~10 ph (100 klx); overcast sky ~0.1-0.2 ph. Wholly superseded by lux and kilolux in modern standards. 1 ph = 10⁴ lx.
About Foot-candles
The foot-candle (fc) equals 1 lm/ft² ≈ 10.764 lx. Standard in North American lighting design: IESNA recommends 30-50 fc for general offices, 50-100 fc for retail displays, 12-16 fc for cinema screens. Still the dominant unit in the US, Canada and some other countries. 1 fc = 1/0.09290304 lx.
Quick Reference Table
| Phots (ph) | Foot-candles (fc) |
|---|---|
| 1 ph | 929.03 fc |
| 2 ph | 1858.06 fc |
| 5 ph | 4645.15 fc |
| 10 ph | 9290.3 fc |
| 25 ph | 23225.8 fc |
| 50 ph | 46451.5 fc |
| 100 ph | 92903 fc |