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Fit Clearance Calculator

Work out fit clearance instantly with clear inputs, formula shown and shareable results.

About Fit Clearance Calculator

A fit is defined by its two extremes. Minimum clearance is the smallest hole against the largest shaft; maximum clearance is the largest hole against the smallest shaft. If the minimum is positive the fit always has clearance, if the maximum is negative it is always interference, and a mixed sign means the fit is a transition and behaviour varies part to part.

Formula

Fit limits

Min clearance = hole min - shaft max; max clearance = hole max - shaft min

Worked example

With the default values below, Fit Clearance Calculator returns Minimum clearance of 0.0070. Change any input above and every figure here is recalculated in your browser.

Inputs used

Minimum hole sizeminimum 0.01 mm
25 mm
Maximum hole sizeminimum 0.01 mm
25.021 mm
Minimum shaft sizeminimum 0.01 mm
24.98 mm
Maximum shaft sizeminimum 0.01 mm
24.993 mm

Results

Minimum clearance
0.0070 mm
Maximum clearance
0.0410 mm
Total variation in fit
0.0340 mm
Fit classification
Clearance fit — always assembles freely

Step by step

  1. 1Values used
  2. 2Fit limits
  3. 3Minimum clearance= 0.0070 mm
  4. 4Maximum clearance= 0.0410 mm
  5. 5Total variation in fit= 0.0340 mm
  6. 6Fit classification= Clearance fit — always assembles freely

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Fit Clearance figure worked out?

Min clearance = hole min - shaft max; max clearance = hole max - shaft min. A fit is defined by its two extremes.

Why is a transition fit sometimes chosen?

It gives accurate location with minimal force. It is acceptable where parts are assembled once and light interference does no harm, but it is a poor choice for anything serviced in the field.

What values do I need to enter?

This calculator takes 4 inputs: Minimum hole size, Maximum hole size, Minimum shaft size, Maximum shaft size. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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Fit Clearance Calculator – Calculate Minimum clearance