Based on the fixed-end beam calculation, and anticipates that the total circumferential force can only be carried by one tooth.
Allowable load
F all = π c b m ≥ F t
where:
| c = 0.065 σ Ab | tooth allowable stress in bending [MPa, psi] | |
| σ Ab | allowable stress in bending (material property) | |
| b | tooth gearing width | |
| m | module | |
| F t | circumferential force acting on the gearing | 
Safety factor
S = F all / F t