🔄 Unit converters

Centimetres to inches converter

Type a number in either box to convert between centimetres and inches. It works both ways and nothing is sent anywhere.

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Result—

    How many inches are in a centimetre?

    To convert centimetres to inches, multiply by 0.39370079. One cm is 0.39370079 in, and one in is 2.54 cm, so to go the other way multiply inches by 2.54 or divide by 0.39370079. The factor is exact: one inch is defined as 2.54 centimetres. Type a number in either box below and the other one updates at once.

    How to convert centimetres and inches

    1 cm = 0.39370079 in, and 1 in = 2.54 cm. The factor is exact: one inch is defined as 2.54 centimetres.

    A quick check: 10 cm is almost 4 inches (exactly 3.937), so divide by 2.5 for a close answer. In the other direction, multiply inches by 2.5 and add a little. For anything that has to fit, such as a frame, a cut or a form field, use the exact figure.

    It runs in your browser. Nothing you type is sent anywhere, and there is no sign-up.

    Common values

    These are the conversions people look up most often, worked out from the exact factor and rounded to six significant digits.

    Centimetres and Inches: common values
    CentimetresequalsInchesequals
    1 cm0.393701 in1 in2.54 cm
    2.5 cm0.984252 in2.5 in6.35 cm
    5 cm1.9685 in5 in12.7 cm
    10 cm3.93701 in10 in25.4 cm
    15 cm5.90551 in15 in38.1 cm
    30 cm11.811 in30 in76.2 cm
    50 cm19.685 in50 in127 cm
    100 cm39.3701 in100 in254 cm

    Where you meet it in Canada

    Canada measures in metric, so lengths on packaging, in shops and at the doctor's office are in centimetres, but inches are still how most people describe screens, tools, pipe, lumber, picture frames and often their own height. A 2×4 board is not 2 by 4 inches, a 55-inch television is about 140 cm across the diagonal, and a US-made product page will list inches. The factor is exact: since the international yard and pound agreement of 1959, one inch has been defined as 2.54 centimetres, so there is no rounding in it.

    When to use it

    • Converting a screen, frame or shelf size between a US listing and a Canadian one
    • Checking a measurement on a sewing pattern or a plan
    • Filling in a form that asks for centimetres when you know inches
    • Converting a child's or a pet's measurements

    Mistakes it helps you avoid

    • Using 2.5 for a precise job: the error grows with the length.
    • Mixing up the direction and dividing when you should multiply.
    • Reading millimetres as centimetres when a measurement has both.
    • Rounding too early when several lengths will be added together.

    The formula

    One multiplication each way.

    • in = cm × 0.39370079
    • cm = in × 2.54 (or in ÷ 0.39370079)

    The factor is exact: one inch is defined as 2.54 centimetres. The result is rounded for display only; the figure in the box keeps up to eight significant digits. Factors come from NIST SP 811 Appendix B.

    Example: 30 cm in inches

    Convert 30 centimetres to inches.

    1. Factor1 cm = 0.39370079 in
    2. Multiply30 × 0.39370079 = 11.811

    30 cm = 11.811 in

    Check: 11.811 ÷ 0.39370079 gives back 30.

    Terms on this page

    Centimetre
    One hundredth of a metre.
    Inch
    A length defined as exactly 2.54 centimetres.

    Common questions

    How many inches are in one cm?

    One cm is 0.39370079 in.

    How many centimetres are in one in?

    One in is 2.54 cm.

    Is the cm to in factor exact?

    The factor is exact: one inch is defined as 2.54 centimetres.

    How do I convert cm to inches in my head?

    Divide by 2.5, or multiply by 0.4. For 50 cm that gives 20 in, against the exact 19.685 in.

    What is 1 inch in cm?

    Exactly 2.54 cm.

    Is anything I type sent to a server?

    No. The conversion happens in your browser and nothing you enter leaves your device.

    What to work out next

    Where these numbers come from

    Last verified 2026-10-25 The method on this page is checked against the sources above at least once a year. Spotted something out of date? Tell us and we will fix it.

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