As we know One W/cm² is equal to 683 ph (1 W/cm² = 683 ph).

To convert Watt/Square Centimeter (at 555 nm) to Phot, multiply your W/cm² figure by 683.

Example : convert 25 W/cm² to ph:

25 W/cm² = 25 × 683 ph = ph

To convert Phot to Watt/Square Centimeter (at 555 nm), divide your ph figure by 683.

Example : convert 25 ph to W/cm²:

25 ph = 25 ÷ 683 W/cm² = W/cm²