The degree of desulfurization is given by:

where

and ks ~ 0.0013 ε0.25 for ε < 60 W tonne−1 while ks ~ 8.1 × 10−6ε2.1 for ε > 60 W tonne−1.
| St | Sulfur at time t in steel |
| S0 | Sulfur at time 0 in steel |
| ks | rate constant |
| t | time |
| Ls | Sulfur coefficient (%S)/[%S] |
| Wm | Mass of steel |
| Ws | Mass of slag |
| ε | stirring power |

Stirring energy / W tonne-1
