Inches to centimetres Converter

How many centimetres are in a inch?

One inch is 2.54 centimetres. The full conversion is centimetres = inches × 2.54, and going the other way you divide instead of multiply.

A few anchor values worth memorising: 2.54 cm to the inch, 25.4 cm to ten, and 254 cm to a hundred. The calculator above handles the rest, including the awkward decimals.

The reference table under the converter lists the values people look up most often, so for a common figure you can read the answer off directly rather than typing anything.

Worked examples

Three worked examples, each multiplying by 2.54:

2.5 in × 2.54 = 6.35 cm. 25 in × 2.54 = 63.5 cm. 250 in × 2.54 = 635 cm.

To reverse any of them, divide instead of multiplying — or use the swap button above, which does the same thing without the arithmetic. Reversing a converted value should return you to exactly what you started with; if it does not, something has been rounded too early.

Doing this conversion in your head

The exact factor is 2.54, which nobody multiplies by in their head. It is very close to 28/11, so multiplying by 28 and dividing by 11 lands within 0.21% of the correct answer — accurate enough for anything short of engineering work.

Since the factor is greater than one, the number always gets bigger: a inch is smaller than a centimetre, so any quantity converts to more of them. If your answer came out smaller, you have divided when you should have multiplied.

That sanity check catches the majority of real conversion errors. Before trusting any converted figure, ask whether the direction of change makes sense — it takes a second and it is the single most effective safeguard there is.

When you need to convert inches to centimetres

Whether you need three decimal places or a rough sense of scale depends entirely on why you are converting, so it is worth being clear about that first.

On the source side, inches are screen diagonals, tyre and wheel sizes, US lumber and plumbing dimensions, and paper measurements. On the target side, centimetres are what tape measures, clothing size charts, furniture listings and school rulers use. The conversion is essentially a translation between those two worlds — most often because a figure produced in one context has to be understood, submitted or acted on in the other.

Where the converted figure will be cut, dosed, billed or filed, round once at the end rather than at each step. For a rough sense of scale, round freely.

None of this leaves your browser. The conversion is a few lines of arithmetic, so there is no server involved and nothing to store.

What a inch and a centimetre actually are

The inch (in). Defined by international agreement in 1959 as exactly 25.4 millimetres.

The centimetre (cm). The everyday metric unit for body measurements, paper and furniture.

Since inches and centimetres both quantify length against a common defined standard, nothing is lost in translating between them. The only imprecision anywhere in this page is deliberate rounding for readability.

Common mistakes when converting inches to centimetres

Watch the direction. Because inch and centimetre are close enough in magnitude to look interchangeable at a glance, converting the wrong way is easy and rarely obvious from the result alone. Check that the number moved the way you expected before using it.

If you are converting many values, change the source unit in the dropdown rather than converting through an intermediate unit. Every extra hop is another rounding opportunity.