How to convert square centimetres to square inches
One square centimetre equals 0.155 square inches, so multiply the number of square centimetres by 0.155:
in² = cm² × 0.155
cm² = in² ÷ 0.155 (1 in² = 6.4516 cm²)
Example: 6.45 cm² → 6.45 × 0.155 = 0.999752 in².
Going the other way, divide by 0.155, or multiply by 6.4516; the square inches to square centimetres converter does it for you.
Everyday values
| Square centimetres | Square inches | For example |
|---|---|---|
| 1 cm² | 0.155 in² | one square centimetre |
| 6.45 cm² | 0.999752 in² | one square inch |
| 100 cm² | 15.5 in² | a 10 × 10 cm square |
| 624 cm² | 96.7202 in² | a sheet of A4 paper |
When you need this conversion
Divide square centimetres by 6.4516 to get square inches. A 10 × 10 cm square is 15.5 in².
Square centimetre to square inch conversion table
| cm² | in² | cm² | in² |
|---|---|---|---|
| 5 cm² | 0.775002 in² | 65 cm² | 10.075 in² |
| 10 cm² | 1.55 in² | 70 cm² | 10.85 in² |
| 15 cm² | 2.325 in² | 75 cm² | 11.625 in² |
| 20 cm² | 3.1 in² | 80 cm² | 12.4 in² |
| 25 cm² | 3.875 in² | 85 cm² | 13.175 in² |
| 30 cm² | 4.65 in² | 90 cm² | 13.95 in² |
| 35 cm² | 5.425 in² | 95 cm² | 14.725 in² |
| 40 cm² | 6.2 in² | 100 cm² | 15.5 in² |
| 45 cm² | 6.975 in² | 105 cm² | 16.275 in² |
| 50 cm² | 7.75 in² | 110 cm² | 17.05 in² |
| 55 cm² | 8.525 in² | 115 cm² | 17.825 in² |
| 60 cm² | 9.3 in² | 120 cm² | 18.6 in² |
About the units
- Square centimetre (cm²): the area of a square 1 cm on each side.
- Square inch (in²): the area of a square 1 inch on each side, exactly 6.4516 cm².
Both are units of area. The conversion factor comes from the exact definitions above, so the calculator is exact; results are only rounded for display (up to six significant digits).
Frequently asked questions
How many square inches are in one square centimetre?
One square centimetre is 0.155 square inches. One square inch is 6.4516 square centimetres.
How do I convert square centimetres to square inches?
Multiply the value in square centimetres by 0.155. To go back, divide by 0.155.
What is 6.45 cm² in square inches?
6.45 cm² = 0.999752 in².
What is 100 cm² in square inches?
100 cm² = 15.5 in².
Sources
- NIST Special Publication 811 (2008), Guide for the Use of the International System of Units (SI), Appendix B: conversion factors.
- NIST Handbook 44 (2024), Appendix C: General tables of units of measurement.
Last reviewed 5 October 2026. Results are estimates; see our disclaimer.