Transferred torque
 
where:
| P | transferred power [lb ft] | |
| n | speed [min -1 ] | 
Pressure on groove supporting surface
1. shaft inside diameter d h > 0
a)  
 
b) if d min ≤d h -> d min = 1.1 d h [mm]
c) if d min ≤ 1.5 d h -> d min = 1.5 d h [mm]
2. shaft inside diameter d h = 0
 
where:
| d min | minimal shaft diameter [in] | |
| d h | shaft inside diameter [inm] | |
| T | torque [lbft] | |
| K a | application factor | |
| K f | fatigue-life factor | |
| S v | desired safety | |
| τ Al | Allowable Shear Stress | 
Minimum splines length to transfer the torque
| 1. Fixed connection: |  | 
| 2. Flexible connection: |  | 
| where: | 
| T | torque [lbft] | |
| K a | application factor | |
| K f | wear-life factor | |
| K w | application factor | |
| K m | load distribution factor | |
| S v | desired safety | |
| d s | middle diameter = (D + d) / 2 [in] | |
| D | outside diameter of groove section [in] | |
| d | inside diameter of groove section [in] | |
| N | number of grooves [-] | |
| h | height of groove = (D - d) / 2 [in] | |
| s | chamfer | |
| h st | connection height h st = h - 2 s [inm] | |
| p Dmin | allowable pressure on supporting surface of shaft or groove [psi] | 
Allowable pressure
| 1. Fixed connection: |  | 
| 2. Flexible connection: |  | 
| where: | 
| T | torque [lb ft] | |
| K a | application factor | |
| K f | wear-life factor | |
| K w | application factor | |
| K m | load distribution factor | |
| S v | desired safety | |
| d s | middle diameter = (D + d) / 2 [in] | |
| D | outside diameter of groove section [in] | |
| d | inside diameter of groove section [in] | |
| N | number of grooves [-] | |
| h | height of groove = (D - d) / 2 [in] | |
| s | chamfer | |
| h st | connection height h st = h - 2 s [in] | |
| l f | active key length [in] | 
Strength Check
p min ≤ p ds
p min ≤ p dh
where:
| p min | minimal calculated h/2 pressure [psi] | |
| p ds | allowable pressure in shaft [psi] | |
| p dh | allowable pressure in hub [psi] |