US customary / imperial

Inch

1 in

One inch is exactly 0.0254 metres.

Exact unit definition · Catalogue uniruler-preview-2026-10-19-r3

What is being measured?

Exactly 0.0254 metres per inch.

The unit relationship is exact. A measured input can still have its own uncertainty.

Dimension
length
Reference value
1 in
Evidence
Exact unit definition
In metres
0.0254 m

Put the length in perspective

One Inch represents approximately 0.297 card lengths measured end to end. This is a length ratio; it does not calculate how the objects pack or fit.

Inch · 0.0254 m

Metre · 1 m

Foot (international) · 0.3048 m

One of each reference, on the same linear scale. Very small lengths may not be visible. This compares length, not area or physical fit.
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