refmanualEngineering, within reach.

Fits & size limits

Nominal size: identify which dimension it names

For a hole/shaft fit, nominal size is the reference used with deviations. For some named products, the size designation must instead be looked up in that product system.

Sources and scope ↓

A fit example

A nominal 25 mm hole with +0.021 / 0 mm deviations has limits 25.000 and 25.021 mm. “25 mm” is not a promise that every delivered part measures exactly 25.000.

A product-name check

Before calculating a clearance, confirm that the label refers to the actual diameter being compared. Do not substitute a pipe or bearing size name for a measured/defined mating dimension.

Continue your task

Calculate clearance from hole and shaft limits →A boxed basic dimension gives a theoretical target →Thou and mil: convert the length, then read the tolerance →

All tolerance and surface references →

Sources and review scope

Reviewed 23 October 2026. Arithmetic examples are labelled separately from source-table facts and standard scope.

ISO 286-1:2010

Public catalogue: terminology, code system and scope. Full clauses not reviewed.

Open the original source ↗
KHK hole tolerance table

Manufacturer table explicitly excerpting JIS B 0401-2:1998. H7 row for 25 mm: 0 / +21 µm.

Open the original source ↗