How to convert cm to inches
The inch has been defined as exactly 2.54 cm by international agreement since 1959, so this is one of the few conversions with no rounding error at all. Example: a 100 cm table edge is 100 ÷ 2.54 = 39.37 inches. For a quick mental estimate, multiply centimeters by 0.4 — 100 cm ≈ 40 in — which runs about 1.6% high.
Cm to inches conversion chart
| cm | inches |
|---|---|
| 1 | 0.39 |
| 2 | 0.79 |
| 3 | 1.18 |
| 4 | 1.57 |
| 5 | 1.97 |
| 1 | 3.94 |
| 15 | 5.91 |
| 2 | 7.87 |
| 25 | 9.84 |
| 3 | 11.81 |
| 4 | 15.75 |
| 5 | 19.69 |
| 6 | 23.62 |
| 7 | 27.56 |
| 8 | 31.5 |
| 9 | 35.43 |
| 1 | 39.37 |
| 12 | 47.24 |
| 15 | 59.06 |
| 18 | 70.87 |
| 2 | 78.74 |
Height: cm to feet & inches
Heights in the US are quoted in feet and inches — divide total inches by 12 for feet, the remainder is inches:
| cm | feet & inches |
|---|---|
| 150 | 4′ 11.1″ |
| 155 | 5′ 1″ |
| 160 | 5′ 3″ |
| 165 | 5′ 5″ |
| 170 | 5′ 6.9″ |
| 175 | 5′ 8.9″ |
| 180 | 5′ 10.9″ |
| 185 | 6′ 0.8″ |
| 190 | 6′ 2.8″ |
| 195 | 6′ 4.8″ |
| 200 | 6′ 6.7″ |
Where this conversion shows up
Screen sizes are the classic trap in reverse — a "24-inch" monitor measures its diagonal, about 61 cm. Clothing and furniture from international shops list cm; US patterns, lumber, and picture frames use inches. When precision matters (printing, woodworking), keep two decimal places: at typical furniture scale, a 0.5 in rounding error is over a centimeter.
Frequently asked questions
How many inches is 1 cm?
1 cm = 0.3937 inches — a little under half an inch. Ten centimeters is 3.94 inches, and 2.54 cm makes exactly one inch.
How many inches is 30 cm?
30 cm = 11.81 inches, just shy of a foot (12 in = 30.48 cm). This is why 30 cm rulers and 12-inch rulers are nearly — but not exactly — the same length.
What is 170 cm in feet and inches?
170 cm is 66.93 inches, which is 5 feet 6.9 inches — usually stated as 5′7″. Divide by 2.54 for inches, then by 12 for feet.
Is the cm-to-inch conversion exact?
Yes. Since 1959 the inch is defined as exactly 2.54 cm, so converting is pure arithmetic — any inaccuracy comes only from rounding the answer.
How do I convert cm to inches in my head?
Multiply by 4 and divide by 10: 50 cm → 200 ÷ 10 = 20 inches (true value 19.69). It overshoots by about 1.6% — fine for shopping, not for carpentry.