How to convert inches to cm
Example: a 10-inch tablet screen (diagonal) is 10 × 2.54 = 25.4 cm. The estimate "add half, then ×10 the small way" also works: inches × 2.5 gets within 1.6% — 10 in ≈ 25 cm.
Inches to cm conversion chart
| inches | cm |
|---|---|
| 1 | 2.54 |
| 2 | 5.08 |
| 3 | 7.62 |
| 4 | 10.16 |
| 5 | 12.7 |
| 6 | 15.24 |
| 7 | 17.78 |
| 8 | 20.32 |
| 9 | 22.86 |
| 1 | 25.4 |
| 12 | 30.48 |
| 15 | 38.1 |
| 18 | 45.72 |
| 2 | 50.8 |
| 24 | 60.96 |
| 27 | 68.58 |
| 32 | 81.28 |
| 36 | 91.44 |
| 4 | 101.6 |
| 48 | 121.92 |
| 55 | 139.7 |
| 65 | 165.1 |
Fractions of an inch
Imperial measurements below an inch come as fractions — the DIY-store staples convert like this:
| Fraction | Decimal (in) | cm |
|---|---|---|
| 1/16″ | 0.0625 | 0.16 |
| 1/8″ | 0.125 | 0.32 |
| 1/4″ | 0.25 | 0.64 |
| 3/8″ | 0.375 | 0.95 |
| 1/2″ | 0.5 | 1.27 |
| 5/8″ | 0.625 | 1.59 |
| 3/4″ | 0.75 | 1.91 |
| 1″ | 1.0 | 2.54 |
Sizes worth recognizing
US Letter paper is 8.5 × 11 in (21.6 × 27.9 cm) — slightly wider and shorter than A4's 21.0 × 29.7 cm, which is why documents reflow between the two. A "55-inch" TV is a 140 cm diagonal; the screen itself is roughly 122 × 68 cm — the number to check against your shelf before buying.
Frequently asked questions
How many cm is 1 inch?
Exactly 2.54 cm — a definition, not a measurement, fixed by international agreement in 1959. Half an inch is 1.27 cm; a quarter inch is 0.635 cm.
How many cm is 12 inches?
12 inches (one foot) is exactly 30.48 cm. That's why a 'foot-long' sandwich is a touch over 30 cm.
What size is a 15.6-inch laptop in cm?
The diagonal is 39.6 cm. A typical 16:9 body measures about 34.5 × 19.4 cm of screen — plus bezels — so check the spec sheet's width/depth for bag fit.
How do I convert inch fractions like 3/8 to cm?
Turn the fraction into a decimal, then multiply by 2.54: 3/8 = 0.375 in × 2.54 = 0.9525 cm. The chart above covers the common hardware sizes.
Why do screens use inches everywhere?
Display manufacturing standardized in the US and the inch stuck as the global convention for diagonals — even in fully metric countries, a '65-inch TV' is the product name rather than a measurement people convert.