How to Convert Square inches to Square centimetres (sq in to cm²)
Area conversions are everyday maths in Singapore property: HDB flats are listed in square metres while condo listings and PSF prices use square feet. This guide shows how to convert square inches into square centimetres by hand, with examples and a quick-reference table.
The conversion
To convert square inches to square centimetres, multiply the value by 6.4516. To go the other way, divide by the same number (or multiply by 0.15500031). For a quick estimate, multiply by about 6.5.
Square centimetres = square inches × 6.4516
Worked examples
- 3 sq in = 19.3548 cm²
- 12.5 sq in = 80.645 cm²
- 75 sq in = 483.87 cm²
Square inches to Square centimetres table
| Square inches | Square centimetres |
|---|---|
| 1 sq in | 6.4516 cm² |
| 2 sq in | 12.9032 cm² |
| 5 sq in | 32.258 cm² |
| 10 sq in | 64.516 cm² |
| 20 sq in | 129.032 cm² |
| 25 sq in | 161.29 cm² |
| 50 sq in | 322.58 cm² |
| 100 sq in | 645.16 cm² |
| 250 sq in | 1,612.9 cm² |
| 500 sq in | 3,225.8 cm² |
| 1,000 sq in | 6,451.6 cm² |
Common questions
Is sq in to cm² exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Square centimetres to Square inches converter.
Mistakes to avoid
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Background
Many conversion factors are exact by definition. The inch has been defined as exactly 2.54 centimetres since 1959, and the pound as exactly 0.45359237 kilograms, so conversions involving them can be as precise as you need.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the Square inches to Square centimetres Converter or browse all area converters.
Run your own numbers: Square inches to Square centimetres Converter