cm to inches Converter

Convert cm to inches instantly (and back).

100% Browser-Based • Local Processing

centimetre (cm)

inch (in)

How this conversion works

The relation

Worked example
    4

    cm to inches conversion table

    CentimetresInches
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    Overview

    What is a cm to inches Converter?

    To convert cm to inches, divide the centimetres by 2.54, because 1 inch = 2.54 cm exactly. So 10 cm ÷ 2.54 = 3.937 inches, and 1 cm = 0.393701 inches. To go back, multiply inches by 2.54. This tool does both instantly and works offline.

    Switching between centimetres and inches is one of the most common conversions there is, whether you're checking a height, buying a TV, cutting fabric, or reading a product listed in the "other" system. The good news is that it's an exact conversion: one inch is defined as exactly 2.54 centimetres, agreed internationally in 1959. Nothing is approximated in the underlying math — only the number of decimals you see.

    This page is a focused cm-to-inches tool. Enter a value in centimetres and it shows the inches instantly; enter inches and it shows centimetres — the two fields mirror each other, so it works both ways without switching modes. Every result comes with the factor it used (1 in = 2.54 cm), so you can verify it by hand.

    Because inches are often read on rulers and tape measures, the tool also shows the nearest fraction alongside the decimal — so 5 cm appears as 1.9685 inches and about 1 31/32 in, which is far easier to mark on a tape than a long decimal. A common-values table below covers the sizes people look up most, from a few centimetres up to typical heights.

    For a quick height check, note that 170 cm is about 66.93 inches, which is roughly 5 feet 6.9 inches. And if you need other length units — millimetres, feet, yards, or miles — use the full Length Converter, which handles all nine units with the same exact-factor approach. Everything here runs on your own device, so there's nothing to upload and no connection needed once the page has loaded.

    Guide

    How to use the cm to inches Converter

    Step 1: Enter the centimetres. Type your value into the cm field

    Decimals are fine.

    Step 2: Read the inches. The result appears instantly as a decimal, with the nearest tape-measure fraction beside it

    Read the inches. The result appears instantly as a decimal, with the nearest tape-measure fraction beside it.

    Step 3: Or go the other way. Type into the inches field instead to convert inches back to centimetres

    Or go the other way. Type into the inches field instead to convert inches back to centimetres.

    Step 4: Check the factor. The exact relationship used (1 in = 2.54 cm) is shown, so you can verify the number

    Check the factor. The exact relationship used (1 in = 2.54 cm) is shown, so you can verify the number.

    Step 5: Copy or refine. Use Copy to grab the result, or adjust the decimal places if you need more precision

    Copy or refine. Use Copy to grab the result, or adjust the decimal places if you need more precision.

    Screens

    cm to inches Converter in action

    The cm to inches converter turning 100 centimetres into 39.3701 inches, with the note underneath reading that one inch is exactly 2.54 centimetres.
    Typing in either box, with the factor underneath
    The cm to inches converter showing its tape-measure line, giving the answer as a nearest fraction of an inch and marking it with an approximately-equals sign.
    The tape-measure reading, in sixteenths
    The centimetres-to-inches reference table listing common values side by side beneath the converter.
    The reference table, ready to read
    The cm to inches converter on a phone screen, the two panes stacked with the swap control between them.
    The same tool on a phone
    Support

    Frequently Asked Questions

    How many inches are in a centimetre?

    One centimetre is 0.393701 inches — a little under four-tenths of an inch. This comes from the exact definition that 1 inch = 2.54 cm, so 1 cm = 1 ÷ 2.54 = 0.393701 in. To convert any number of centimetres to inches, divide by 2.54. The tool shows this factor with every result.

    Is one inch exactly 2.54 cm?

    Yes, exactly. Since the international yard-and-pound agreement of 1959, one inch is defined as precisely 2.54 centimetres — it's a definition, not a measurement, so there's no rounding in the relationship itself. That's why 2 inches is exactly 5.08 cm and 10 inches is exactly 25.4 cm. Only the displayed decimals are rounded.

    What's the formula to convert cm to inches?

    Inches = centimetres ÷ 2.54. Divide your centimetre value by 2.54 to get inches, because one inch is 2.54 cm. For example, 30 cm ÷ 2.54 = 11.81 inches. To reverse it, multiply inches by 2.54 to get centimetres. It's a single exact factor, which the tool shows alongside each result.

    How do I convert inches back to cm?

    Multiply the inches by 2.54. Because one inch is exactly 2.54 cm, inches × 2.54 gives you centimetres — so 6 inches × 2.54 = 15.24 cm. The tool is bidirectional: type into the inches field and it converts to cm automatically, or type into the cm field to go the other way.

    How many inches is 10 cm?

    10 cm is 3.937 inches, or about 3 15/16 inches on a ruler. The math is 10 ÷ 2.54 = 3.9370. For a few other common ones: 5 cm = 1.9685 in, 20 cm = 7.874 in, 30 cm = 11.811 in, and 50 cm = 19.685 in. The full table on this page lists more.

    What is 170 cm in inches, and in feet and inches?

    170 cm is 66.93 inches. Since there are 12 inches in a foot, that's about 5 feet 6.9 inches — a common human height. The calculation is 170 ÷ 2.54 = 66.929 inches, then 66.929 ÷ 12 = 5 feet with 6.93 inches left over. The tool gives the inch figure; divide by 12 for feet and inches.

    How do I read centimetres as inches on a ruler?

    Convert to inches, then use the nearest fraction. Rulers and tape measures are marked in fractions like 1/16 and 1/32, not decimals, so the tool shows both — for example, 5 cm is 1.9685 in, which is about 1 31/32 in (just shy of 2 inches). Mark the fraction; use the decimal only when you need exact precision.

    Why do both centimetres and inches exist?

    They come from different measurement systems. Centimetres are part of the metric system used by most of the world and all of science. Inches are part of the imperial and US customary systems, still standard in the United States and common in the UK for some uses. Because both are widespread, converting between them is an everyday need — which is exactly what this tool is for.

    What is 1 cm in inches as a fraction?

    One centimetre is 0.393701 inches, which is approximately 25/64 inch, or close to 3/8 inch (0.375) for rough work. Because a centimetre doesn't land neatly on a common ruler mark, the fraction is always an approximation — the tool labels it with "≈". For anything precise, use the decimal value of 0.3937 inches.

    Is this converter exact, or does it round the answer?

    The math is exact — it uses the defined factor 1 inch = 2.54 cm, which is precise by international agreement. Only the displayed value is rounded for readability, and you can add decimal places for more precision. The fraction readout is deliberately approximate (nearest 1/16 or 1/32) and marked "≈"; the decimal is the exact figure.

    Where can I convert other length units like mm, feet, or miles?

    Use the full Length Converter. This page is focused on the cm-to-inches pair, but the Length Converter handles all nine units — millimetres, metres, kilometres, inches, feet, yards, miles, and nautical miles — with the same exact-factor approach and an all-units table. For feet↔metres specifically, there's a dedicated feet-to-meters page too.

    Does the tool work offline, and does it upload my data?

    It works fully offline once the page has loaded, and it never uploads anything. The conversion is a single division by 2.54, done on your own device — no server, no account, no tracking. That makes it reliable with no signal, and private by design, since there's nothing to send anywhere.

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