How to convert cm to inches
The conversion rests on a single exact definition: since 1959, 1 inch = 2.54 centimetres, precisely. That makes the formula a one-step division:
inches = centimetres ÷ 2.54
Worked example: say a parcel is 30 cm long. Divide by 2.54 and you get 30 ÷ 2.54 = 11.81 inches. That's it: no lookup tables, no approximation, just division by an exact constant. The only rounding happens in the digits you choose to display.
Going the other way is just as simple. Multiply instead of divide: cm = inches × 2.54. So a 24-inch monitor measures 24 × 2.54 = 60.96 cm across the diagonal.
Handy mental shortcut: 1 cm is about 0.39 inches, so multiplying centimetres by 0.4 gets you close enough for a quick estimate. For the exact answer, use the converter above or the chart below.
cm to inches chart
Every value below is computed with the exact formula (cm ÷ 2.54) and rounded to two decimal places.
| Centimetres | Inches |
|---|---|
| 1 cm | 0.39 in |
| 2 cm | 0.79 in |
| 3 cm | 1.18 in |
| 4 cm | 1.57 in |
| 5 cm | 1.97 in |
| 6 cm | 2.36 in |
| 7 cm | 2.76 in |
| 8 cm | 3.15 in |
| 9 cm | 3.54 in |
| 10 cm | 3.94 in |
| 11 cm | 4.33 in |
| 12 cm | 4.72 in |
| 15 cm | 5.91 in |
| 20 cm | 7.87 in |
| 25 cm | 9.84 in |
| 30 cm | 11.81 in |
| 40 cm | 15.75 in |
| 50 cm | 19.69 in |
| 100 cm | 39.37 in |
Height conversions
Heights are where cm-to-inches questions come up most. The table gives each height in total inches, then in the feet-and-inches format used on passports, dating profiles and doctor's charts (1 foot = 12 inches).
| Centimetres | Inches | Feet & inches |
|---|---|---|
| 150 cm | 59.06 in | 4 ft 11.1 in |
| 160 cm | 62.99 in | 5 ft 3.0 in |
| 165 cm | 64.96 in | 5 ft 5.0 in |
| 170 cm | 66.93 in | 5 ft 6.9 in |
| 175 cm | 68.90 in | 5 ft 8.9 in |
| 180 cm | 70.87 in | 5 ft 10.9 in |
| 185 cm | 72.83 in | 6 ft 0.8 in |
| 190 cm | 74.80 in | 6 ft 2.8 in |
Beyond heights, this conversion turns up constantly: screen sizes are sold in inches while your desk is measured in centimetres; sewing patterns from the US give seam allowances in inches while your tape measure reads metric; and flat-pack furniture dimensions need translating before you know whether the bookcase fits the alcove. Whatever the job, the same exact ÷ 2.54 applies. Need a different unit pair, such as metres to feet or kilograms to pounds? The universal converter handles every common measurement family.