Taper & Draft Calculator

Convert between taper per foot/inch, included angle, and diameter change for tapers and draft.

A taper is a uniform change in diameter along a length, often quoted as taper per foot (TPF) or as an included angle. The two are interchangeable through the part length.

Formula: TPF = (D − d) / L(in) × 12; Included angle = 2·atan((D−d) / (2L))

Worked Example

  1. D = 1.000 in, d = 0.750 in over L = 3.000 in.
  2. TPF = (0.250 / 3.0) × 12 = 1.000 in/ft; angle = 2·atan(0.250/6.0) ≈ 4.77°.

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