Cm to Inches Converter
Convert centimeters to inches instantly — exact, free, and no sign-up required.
Runs entirely in your browser — nothing you type is uploaded or stored.
How to convert centimeters to inches
To convert centimeters to inches, divide by 2.54 — this is the exact, internationally defined length of one inch, fixed in 1959 alongside the pound. Multiplying by 0.393701 gives the same result. Unlike many historical imperial units, the inch has had one precise metric definition since then, so there's no ambiguity to worry about (older "survey" inches used in US land surveying differ by a few parts per million, but that distinction only matters for geodetic work, not everyday or most engineering conversions).
Worked example: screen and paper sizes
A sheet of A4 paper measures 21.0 × 29.7 cm, which converts to 8.268 × 11.693 inches — close to, but not exactly, the 8.5 × 11 inch US Letter size. That small mismatch (about a quarter of an inch in width) is why A4 documents print with slightly different margins on US Letter-configured printers, and vice versa.
Common mistake: rounding too early
For precision work — machining, 3D printing, technical drawings — rounding 2.54 to "2.5" introduces a 1.6% error that compounds across larger dimensions. A 1-metre part converted with the rounded factor would be off by 1.6 cm, enough to matter in a tight-tolerance assembly. The calculator above always uses the exact 2.54 cm/inch factor, regardless of how many decimal places you enter.
Quick reference
| Centimeters | Inches |
|---|---|
| 1 cm | 0.3937 in |
| 2.54 cm | 1 in |
| 15 cm | 5.906 in |
| 30 cm | 11.811 in |
| 100 cm | 39.37 in |
Need inches to centimeters instead? Use the swap button above to flip the conversion.
How to use the converter
Three steps. No account, no download, no waiting.
Confirm the units
This page is pre-set to cm to inches. Change either dropdown any time to switch units or category — every other EngiConvert category is available from the same selector.
Enter your value
Type a number into the "From" box. The result updates instantly as you type — no button to press.
Copy your result
Use the swap button to flip the conversion, or hit "Copy result" to grab the converted value.
Frequently asked questions
How many inches is 1 cm?
1 centimeter equals 0.393701 inches.
How many cm is 1 inch exactly?
Exactly 2.54 cm, by international definition since 1959.
Is this precise enough for engineering drawings?
Yes — the calculator uses the exact 2.54 cm/inch definition and shows results to 8 significant figures, well beyond what's needed for typical drawing tolerances.
Why do US clothing and shoe sizes still use inches?
US sizing systems were standardized before metrication efforts took hold domestically, and since clothing sizing is already a loose approximation rather than a precise measurement, there's been little commercial pressure to convert it to metric, unlike manufacturing and engineering sectors that trade internationally.
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