Lathe Taper Angle Calculator
Calculate taper half-angle, included angle and diameter change per axial length.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Resolve the diameter difference into a radial change over the axial taper length.
Half-angle=atan((large−small)/(2 length)); taper=(large−small)/length
Worked example
Diameters 40 and 30 mm over 100 mm length give half-angle about 2.86240523° and included angle 5.72481045°.
Assumptions and input details
Requires large diameter greater than small. Angles refer to ideal geometry; machine dial conventions, tool deflection and fit classes are not inferred.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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