Based on the fixed-end beam calculation. Includes the majority of effects. Accessible only for English units.
Safety factor of contact fatigue
 
where:
| S fe | contact fatigue limit (material property) | |
| F t | tangential force acting at teeth | |
| b w | operating tooth width | 
Safety factor of bending fatigue
 
where:
| s n | bending fatigue limit (material property) | |
| b wF1,2 = min (b 1,2 , b w + 2m) | tooth width for bending | 
Factor calculations
 
where:
| μ | Poisson's ratio (material property) | 
| E | modulus of elasticity (material property) | 
| I | |
| 
 | |
| C Li | life factor | 
| P et | tangential diametral pitch (tangential module reverse ratio) | 
| C R | reliability factor | 
| K v | |
| K o | overload factor | 
| K m | |
| J | |
| C G | gradient factor | 
| C G = 1 | CG = 1 for P > 5 | 
| C S | |
| k r | reliability factor | 
| k t | temperature | 
| k ms | mean stress factor |