Square inches to square centimetres
Multiply square inches by 6.4516 to get square centimetres.
20 in² = 129.032 cm²
How to convert square inches to square centimetres
The square centimetre is one ten-thousandth of a square metre (10⁻⁴ m²). The square inch is exactly 6.4516 cm² (2.54 cm squared).
Worked example — 20 in²: 20 × 6.4516 = 129.032 cm².
Square inches to square centimetres table
| Square inches | Square centimetres |
|---|---|
| 1 in² | 6.4516 cm² |
| 2 in² | 12.9032 cm² |
| 5 in² | 32.258 cm² |
| 10 in² | 64.516 cm² |
| 20 in² | 129.032 cm² |
| 50 in² | 322.58 cm² |
| 100 in² | 645.16 cm² |
| 144 in² | 929.0304 cm² |
| 500 in² | 3,225.8 cm² |
Reverse and related
About square inches and square centimetres
Square inch (in²)
1 in² = 6.4516 cm²Definition. Exactly 6.4516 cm² (2.54 cm squared)
History and origin
The square inch is a square one inch on each side, derived from the inch fixed at 2.54 centimetres in 1959. It equals exactly 6.4516 square centimetres.
Current use
Square inches measure small parts, print areas and screens.
Source: NIST Handbook 44, Appendix C (area); 1959 yard-and-pound agreement
Square centimetre (cm²)
1 cm² = 0.155 in²Definition. One ten-thousandth of a square metre (10⁻⁴ m²)
History and origin
The square centimetre is one ten-thousandth of a square metre, part of the decimal metric system. Its small size suits fine measurements.
Current use
Square centimetres measure small areas and material samples.
Source: BIPM SI Brochure (2019)
Where people use this
Square inches: small parts, print and screens. Square centimetres: small areas, material samples. 1 sq in is exactly 6.4516 cm².
Every value is carried to full double precision; the display is rounded.
Sources: BIPM SI Brochure (2019); NIST Handbook 44, Appendix C (area); 1959 yard-and-pound agreement.
Questions people ask
How many cm² in a square inch?
One square inch is exactly 6.4516 cm².
How many cm² is 10 sq in?
10 sq in is about 64.5 cm².
How many sq in in a square foot?
One square foot is 144 square inches.