Usually calculated based on Module and Reference Diameter. Formula: $A = 10 \times m + 0.63 \times d$ (This is a simplified approximation for IT grades).
Development of a Semi-Analytical Excel Tool for DIN 5480 Spline Dimension Calculation and Tolerance Verification din 5480 spline calculator excel
Formulas can be modified to add custom parameters or specific project constraints. Usually calculated based on Module and Reference Diameter
Approximate logic for Excel: You need to calculate the pressure angle at the center of the ball ($\alpha_M$). din 5480 spline calculator excel
Structure of 'Data' Sheet: