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UnitFormula

Centimeters to inches

Multiply centimeters by 0.393701 to get inches.

1 cm = 0.393701 inBIPM SI · NIST HB 44
cm
3.937in

10 cm = 3.937 in

Worked examples

2.54 cm is exactly 1 inch, by the 1959 definition of the international inch as 25.4 mm. There is no rounding in this direction.

A-series paper is 210 mm, or 21 cm, wide. That width is 8.2677 in, just under 8 1/4 in (8.25 in = 20.955 cm).

Centimeters to inches table

Common conversions.
CentimetersInchesNearest 1/16 in
1 cm0.393701 in3/8 in
1.25 cm0.492126 in1/2 in
1.5 cm0.590551 in9/16 in
1.75 cm0.688976 in11/16 in
2 cm0.787402 in13/16 in
2.5 cm0.984252 in1 in
3 cm1.1811 in1 3/16 in
3.5 cm1.378 in1 3/8 in
4 cm1.5748 in1 9/16 in
4.5 cm1.7717 in1 3/4 in
5 cm1.9685 in1 15/16 in
6 cm2.3622 in2 3/8 in
7 cm2.7559 in2 3/4 in
7.5 cm2.9528 in2 15/16 in
8 cm3.1496 in3 1/8 in
9 cm3.5433 in3 9/16 in
10 cm3.937 in3 15/16 in
12.5 cm4.9213 in4 15/16 in
15 cm5.9055 in5 7/8 in
17.5 cm6.8898 in6 7/8 in
20 cm7.874 in7 7/8 in
25 cm9.8425 in9 13/16 in
30 cm11.811 in11 13/16 in
35 cm13.7795 in13 3/4 in
40 cm15.748 in15 3/4 in
45 cm17.7165 in17 11/16 in
50 cm19.685 in19 11/16 in
60 cm23.622 in23 5/8 in
70 cm27.5591 in27 9/16 in
75 cm29.5276 in29 1/2 in
80 cm31.4961 in31 1/2 in
90 cm35.4331 in35 7/16 in
100 cm39.3701 in39 3/8 in

Inches to centimeters table

Common conversions.
InchesCentimeters
1 in2.54 cm
2 in5.08 cm
4 in10.16 cm
6 in15.24 cm
8 in20.32 cm
10 in25.4 cm
12 in30.48 cm
14 in35.56 cm
16 in40.64 cm
18 in45.72 cm
20 in50.8 cm
22 in55.88 cm
24 in60.96 cm
26 in66.04 cm
28 in71.12 cm
30 in76.2 cm
32 in81.28 cm
34 in86.36 cm
36 in91.44 cm
38 in96.52 cm
40 in101.6 cm
42 in106.68 cm
44 in111.76 cm
46 in116.84 cm
48 in121.92 cm
50 in127 cm
52 in132.08 cm
54 in137.16 cm
56 in142.24 cm
58 in147.32 cm

Reverse and related

mm → in1 mm = 0.0393701 inin → ft1 in = 0.0833333 ftft → m1 ft = 0.3048 mmi → km1 mi = 1.6093 kmm → yd1 m = 1.0936 ydyd → ft1 yd = 3 ft

About centimeters and inches

The international inch is defined as 25.4 mm exactly, so 2.54 cm per inch. The centimeter is 1/100 of the meter, the SI base unit of length.

Where people use this

Clothing sizes, TV diagonals, and hardware in the United States are often in inches; pattern sheets and most of the world’s rulers are in centimeters. A 30 cm ruler is 11.811 in; a 12 in ruler is 30.48 cm.

Rainfall totals and snow depths are reported in centimeters in SI countries and in inches in the United States. 2.5 cm of rain is 0.984 in, not “1 inch exactly” (that would be 2.54 cm).

Common mistakes

The exact factor is 1 in = 2.54 cm, so 1 cm = 0.3937007874 in. “Divide by 2.5” is 1.6% high. The US survey inch, retired for new work, does not apply to a clothing tape or a rain gauge. Also do not mix this length inch with a column-inch (area) or a board inch (volume).

How we know this is right
1 in = 2.54 cm, so 1 cm = 1 ÷ 2.54 = 0.393701 in.

Sources: International Yard and Pound Agreement (1959); NIST Handbook 44, App. C; BIPM, The International System of Units (SI), 9th ed. (2019).

Sources

Questions people ask

How many inches is 2.54 cm?

Exactly 1 inch. The international inch is defined as 25.4 mm.

How many inches is 21 cm?

8.2677 in. Divide centimeters by 2.54.

How many centimeters is 12 inches?

Exactly 30.48 cm.

Is 1 inch 2.5 cm?

No. 1 inch is 2.54 cm exactly. Using 2.5 cm makes every inch 1.6% short.