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Angles & measurement

Taper Calculator

Find a taper angle from a width change.

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Your measurements

Decimals and fractions work: try 0.75, 3/4, or 1 1/2.

Your result
2.3859
degrees per tapered side
Lateral offset per side25 mm
Taper ratio1 : 24
Know what goes into your result.

Formula, assumptions, and a worked example are below. All calculations stay in this page.

How to use the taper calculator

  1. Measure the wide and narrow ends of the tapered section.
  2. Enter only the length over which the taper occurs.
  3. Choose a single tapered edge or two equal tapered edges. Read the offset and angle for each tapered side.

The formula

Taper angle = atan(lateral offset per side ÷ taper length)

Worked example

A one-sided taper from 50 to 25 mm over 600 mm has a 25 mm offset and a 2.386° angle. A symmetric taper uses half the offset per side.

Before you measure and cut

For a table leg with an untapered top section, exclude that top section from the taper length.

The angle describes the taper line, not a complete jig setup. Secure the workpiece using a jig suitable for your tool.

Frequently asked questions

What happens when the end widths are equal?

The angle is zero and both sides are parallel.

Can this calculate a four-sided leg?

Use the symmetric setting for each opposing pair of faces, checking the relevant width in each plane.