How to convert square inches to square centimetres
One square inch equals 6.4516 square centimetres, so multiply the number of square inches by 6.4516:
cm² = in² × 6.4516
in² = cm² ÷ 6.4516 (1 cm² = 0.155 in²)
Example: 4 in² → 4 × 6.4516 = 25.8064 cm².
Going the other way, divide by 6.4516, or multiply by 0.155; the square centimetres to square inches converter does it for you.
Everyday values
| Square inches | Square centimetres | For example |
|---|---|---|
| 1 in² | 6.4516 cm² | one square inch |
| 4 in² | 25.8064 cm² | a 2 × 2 in photo |
| 93.5 in² | 603.225 cm² | a sheet of US Letter paper |
When you need this conversion
One square inch is exactly 6.4516 cm². Pressure in psi is force per square inch, which is why the square inch appears so often in technical work.
Square inch to square centimetre conversion table
| in² | cm² | in² | cm² |
|---|---|---|---|
| 1 in² | 6.4516 cm² | 13 in² | 83.8708 cm² |
| 2 in² | 12.9032 cm² | 14 in² | 90.3224 cm² |
| 3 in² | 19.3548 cm² | 15 in² | 96.774 cm² |
| 4 in² | 25.8064 cm² | 16 in² | 103.226 cm² |
| 5 in² | 32.258 cm² | 17 in² | 109.677 cm² |
| 6 in² | 38.7096 cm² | 18 in² | 116.129 cm² |
| 7 in² | 45.1612 cm² | 19 in² | 122.58 cm² |
| 8 in² | 51.6128 cm² | 20 in² | 129.032 cm² |
| 9 in² | 58.0644 cm² | 21 in² | 135.484 cm² |
| 10 in² | 64.516 cm² | 22 in² | 141.935 cm² |
| 11 in² | 70.9676 cm² | 23 in² | 148.387 cm² |
| 12 in² | 77.4192 cm² | 24 in² | 154.838 cm² |
About the units
- Square inch (in²): the area of a square 1 inch on each side, exactly 6.4516 cm².
- Square centimetre (cm²): the area of a square 1 cm on each side.
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 centimetres are in one square inch?
One square inch is 6.4516 square centimetres. One square centimetre is 0.155 square inches.
How do I convert square inches to square centimetres?
Multiply the value in square inches by 6.4516. To go back, divide by 6.4516.
What is 4 in² in square centimetres?
4 in² = 25.8064 cm².
What is 93.5 in² in square centimetres?
93.5 in² = 603.225 cm².
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.