Convert inches to centimetres
Turn inches into centimetres exactly. Understands 5 1/2, 5½ and 5'6" entries, gives mm and metres too, and converts a pasted column in one go.
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centimetres = inches × 2.54 = 12 × 2.54 = 30.48 cm 1 in = 2.54 cm
| inches | centimetres | Feet and inches |
|---|---|---|
| 0.25 in | 0.64 cm | 0 ft 0.25 in |
| 0.5 in | 1.27 cm | 0 ft 0.50 in |
| 1 in | 2.54 cm | 0 ft 1.00 in |
| 2 in | 5.08 cm | 0 ft 2.00 in |
| 3 in | 7.62 cm | 0 ft 3.00 in |
| 4 in | 10.16 cm | 0 ft 4.00 in |
| 5 in | 12.70 cm | 0 ft 5.00 in |
| 6 in | 15.24 cm | 0 ft 6.00 in |
| 8 in | 20.32 cm | 0 ft 8.00 in |
| 10 in | 25.40 cm | 0 ft 10.00 in |
| 12 in | 30.48 cm | 1 ft 0.00 in |
| 18 in | 45.72 cm | 1 ft 6.00 in |
| 24 in | 60.96 cm | 2 ft 0.00 in |
| 30 in | 76.20 cm | 2 ft 6.00 in |
| 36 in | 91.44 cm | 3 ft 0.00 in |
| 48 in | 121.92 cm | 4 ft 0.00 in |
| 60 in | 152.40 cm | 5 ft 0.00 in |
| 72 in | 182.88 cm | 6 ft 0.00 in |
Multiply by 2.54 — and nothing else
Going from inches to centimetres is the easy direction: one multiplication by a number most people can remember. 12 in × 2.54 = 30.48 cm. 36 in × 2.54 = 91.44 cm. The factor is exact by international definition, so unlike most unit conversions there is no accumulated error to worry about however many times you apply it.
Typing inches the way they are written
Imperial measurements are almost never written as decimals. A cut list says 3/8, a shirt says 15 1/2, a doorway says 6'8". Retyping those as 0.375, 15.5 and 80 is where mistakes creep in, so this converter reads all of the following directly:
| You type | Read as | Result |
|---|---|---|
| 5.5 | 5.5 in | 13.97 cm |
| 5 1/2 | 5.5 in | 13.97 cm |
| 5½ | 5.5 in | 13.97 cm |
| 3/8 | 0.375 in | 0.9525 cm |
| 5'6" | 66 in | 167.64 cm |
| 5 ft 6 in | 66 in | 167.64 cm |
When a composite entry is recognised, the page tells you how it read it, so a mistyped apostrophe cannot silently turn five foot six into five and a half inches.
Should you use centimetres or millimetres?
For anything technical, millimetres. Continental European engineering and joinery drawings are dimensioned in whole millimetres precisely so that no decimal point can be lost in a photocopy, and CNC, laser and 3D-printing toolchains almost all expect millimetres. The millimetre figure is shown next to the centimetre result for that reason.
Centimetres win for body measurements, clothing, furniture and anything a shop assistant will read out. 40 in is 101.6 cm; a 34 in inside leg is 86.4 cm.
Fabric, screens and the places this bites
Fabric is sold by the yard in the US and by the metre almost everywhere else, and a metre is 3.37 in longer than a yard. Ordering "five yards" of a fabric priced per metre gets you 43 cm more cloth and a bigger bill than you expected.
Screen sizes are quoted as a diagonal in inches worldwide, even in fully metric countries. A 55 in television is 139.7 cm corner to corner, but its width is only about 121.8 cm — check the width against your alcove, not the advertised diagonal.
Doing a whole list at once
Paste a column of inch measurements into the Batch tab and get centimetres back, one per line, blank lines intact. Fractions are parsed there too, so a cut list copied straight out of a plan converts without any retyping. It runs locally; nothing is uploaded.
Questions
How do I enter a fractional inch?
Type it the way the drawing prints it. 5 1/2, 5½, 11/16 and 0.6875 are all accepted, as is a full feet-and-inches entry such as 5'6" or 5 ft 6 in.
What is 1 inch in cm?
Exactly 2.54 cm, by definition. That also makes 1 inch exactly 25.4 mm and 12 inches exactly 30.48 cm.
Should I use cm or mm for a workshop drawing?
Millimetres, almost always. Engineering and joinery drawings across Europe are dimensioned in whole millimetres to avoid decimal points, and the mm figure is shown alongside the centimetre result for that reason.
How precise is the result?
As precise as you ask for, up to eight decimal places. Because the ratio is exact, extra decimals are real digits rather than rounding noise.