1 inches in cm
1 in = 2.54 cm = 25.4 mm = 0.0254 m
Working: 1 × 2.54 = 2.54
1 inches is 2.54 centimetres, or 25.4 millimetres.
The conversion is exact rather than approximate: since 1959 the international inch has been defined as precisely 2.54 centimetres, so multiplying by 2.54 gives an exact answer with no rounding error. 1 × 2.54 = 2.54 cm. To go back the other way, divide by 2.54; for millimetres, multiply the inches by 25.4 instead.
Metric trades work in millimetres rather than centimetres, and 1 inches is 25.4 mm — the figure a drawing or a parts list would actually carry. The nearest whole centimetre is 3, 0.46 cm away.
One inch is exactly 2.54 centimetres by definition, not by measurement — the two systems were formally tied together at this value in 1959. Every other inch-to-centimetre conversion is just this one scaled up, which is why none of them carry any rounding error.
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Frequently asked questions
How many cm is 1 inches?
1 inches is 2.54 cm. Multiply the number of inches by 2.54 to convert to centimetres.
Is the inch to cm conversion exact?
Yes. The international inch has been defined as exactly 2.54 centimetres since 1959, so the conversion introduces no rounding error.
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For any other value, use the full Length Converter on BrainVert.