Calculating Screw Thread Properties

Metric screw sizes are calculated as follows:

Minor diameter = Major diameter - (1.226869 x pitch)

Pitch diameter = Major diameter - (.649519 x pitch)

The tensile stress area = ((root dia + pitch dia) / 2)^2 * Pi/4

Inch screw sizes are calculated as follows:

Minor diameter = Major diameter - (1.299038 x pitch)

Pitch diameter = Major diameter - (.649519 x pitch)

The tensile stress area = ((minor dia + pitch dia) / 2)^2 * Pi/4