Calculate taper per foot, a missing diameter, required axial length, or equivalent angle and ratio specifications. Compare a trial cut with a target and optionally show setup estimates or step-off diameters.

Diameter change per foot of axial length. Choose the unit beside each measurement. Use diameters, not radii.

Setup outputs (optional)

Blank omits approximate tailstock set-over. Must cover the axial taper length.

Blank omits the diameter table. At most 16 rows, including both endpoints.

Related Calculators

Taper Per Foot Formula

With large and small diameters in inches and axial length in feet, the following formula gives taper per foot in inches per foot. The calculator converts each selected linear input unit before applying the relationship.

TPF = (LD - SD) / L

Variables:

  • TPF is the taper per foot (inches/foot)
  • LD is the large diameter (inches)
  • SD is the small diameter (inches)
  • L is the length over which the taper is measured (feet)

To calculate taper per foot with diameters in inches and length in feet, subtract the small diameter from the large diameter and divide by the length. If all three dimensions are in inches instead, use TPF = 12 ร— (LD โˆ’ SD) / L. The factor of 12 converts the axial inch basis to a foot; it is not applied again when L is already in feet.

What is Taper Per Foot?

Taper per foot is a measure of the gradual decrease in diameter of a conical shape or hole over a specified length. It is commonly used in engineering and manufacturing to describe the shape of tools, machine elements, or holes that are not cylindrical but taper in diameter from one end to the other. The rate describes taper geometry, but does not by itself establish a standard taper, size, tolerance, or fit.

How to Calculate Taper Per Foot?

The following steps outline how to calculate the Taper Per Foot.

  1. First, measure the large diameter (LD) at the wider end of the object or hole.
  2. Next, measure the small diameter (SD) at the narrower end.
  3. Then, measure the length (L) over which the taper occurs.
  4. Use TPF = (LD - SD) / L with diameters in inches and L in feet, or multiply by 12 when all three dimensions are in inches.
  5. Choose the matching solve mode in the calculator, select each measurementโ€™s unit, enter the visible required quantities, and select Calculate. In a specification mode, choosing a new specification type clears the numeric value so it can be entered in the new convention.

Example Problem :

Use the following variables as an example problem to test your knowledge.

Large Diameter (LD) = 2 inches

Small Diameter (SD) = 1 inch

Length (L) = 4 feet. Therefore TPF = (2 โˆ’ 1) / 4 = 0.25 in/ft. Enter 2 in, 1 in, and 4 ft in Taper per foot from diameters; equivalently, entering length 48 in gives the same result.