Flash Guide Number Calculator
Calculate flash power, aperture, and distance
Flash Exposure Calculator
f/12
Aperture for Distance
4.5 m
Max Distance for Aperture
36
Effective GN at ISO
100%
Required Power
Guide Number = Distance × Aperture | GN scales with √(ISO/100)
Common Flash Guide Numbers
| Flash Type | GN (m) | GN (ft) |
|---|---|---|
| Built-in (crop) | 12 | 39 |
| Built-in (FF) | 15 | 49 |
| Speedlight (mid) | 36 | 118 |
| Speedlight (pro) | 58 | 190 |
| Studio Strobe | 60-80 | 200-260 |