Taper Calculator
Enter the large diameter, small diameter, and length of a tapered part to get its taper rate, taper angle, and taper per foot.
What This Calculator Does
A taper describes how much a round or flat workpiece narrows over its length, commonly used for machine tapers, shafts, pins, and fittings. This calculator converts the large diameter, small diameter, and length of a tapered section into the most common ways machinists express taper: taper per foot, taper per inch, included angle, and taper ratio.
The Formula
The diameter difference (large minus small) divided by the length gives taper per inch; multiplying by 12 gives taper per foot. The half-angle is found from the arctangent of half the diameter difference over the length, and doubling it gives the full included angle. The taper ratio expresses the same slope as “1 unit of diameter change per x units of length.”
Good to Know
- Make sure both diameters and the length use the same unit system before entering values.
- This tool is for general shop planning and estimation, not a substitute for precision gauge verification on finished parts.