Convert Lumens per square inch to Phots
Convert Lumens per square inch (lm/in²) to Phots (ph) instantly and accurately.
Conversion Formula
ph = lm/in² × 0.15500031
About Lumens per square inch
The lumen per square inch (lm/in²) equals 1/0.00064516 lx ≈ 1 550 lx. Used in US optics and LED backlight datasheets when specifying output over small aperture areas. Rare in general lighting but found in US optical engineering catalogs and LCD backlight specifications. 1 lm/in² = 1/0.00064516 lx.
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 Wholly superseded by lux and kilolux in modern standards. 1 ph = 10⁴ lx.
Quick Reference Table
| Lumens per square inch (lm/in²) | Phots (ph) |
|---|---|
| 1 lm/in² | 0.155 ph |
| 2 lm/in² | 0.310001 ph |
| 5 lm/in² | 0.775002 ph |
| 10 lm/in² | 1.55 ph |
| 25 lm/in² | 3.87501 ph |
| 50 lm/in² | 7.75002 ph |
| 100 lm/in² | 15.5 ph |