Fits & tolerances
Clearance vs Transition vs Interference Fits
A practical guide to clearance, transition and interference fits, including how limit dimensions determine the actual fit class.
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A clearance fit guarantees positive clearance at the worst-case limits. The smallest permissible hole remains larger than the largest permissible shaft.
Transition fit
A transition fit can produce either small clearance or small interference depending on the actual manufactured sizes within their tolerance zones.
Interference fit
An interference fit guarantees overlap at the limit sizes. Assembly force, contact pressure, material properties, wall thickness, surface condition and temperature can become important design variables.
Related standards
DraftFit guides are engineering educational content and do not replace the controlled standard, project specification or responsible-engineer review.