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 — metres to feet, kilograms to pounds? The universal converter handles every common measurement family.