Square millimeters (mm²) to Square inches (in²) Conversion
Square millimeters
The square millimetre is a unit of area equal to one millionth of a square metre (10⁻⁶ m²). In engineering, cross-sectional areas of wires and cables are standardised in square millimetres — electrical cable ratings specify conductor cross-sections in mm² (e.g., 1.5 mm², 2.5 mm², 4 mm²). In materials testing, stress is calculated as force per unit area in megapascals, where the area is expressed in square millimetres.
Square inches
The square inch is a unit of area equal to exactly 6.4516 cm² (the square of 2.54 cm). It is used in engineering for specifying material cross-sections, pressure calculations (pounds per square inch = psi), and the dimensions of small components. Tile and flooring materials in the United States are sometimes measured in square inches for small-format tiles.
| Square millimeters (mm²) | Square inches (in²) |
|---|---|
| 0.1 mm² | 0.000155 in² |
| 1 mm² | 0.00155 in² |
| 2 mm² | 0.0031 in² |
| 3 mm² | 0.00465 in² |
| 5 mm² | 0.00775 in² |
| 10 mm² | 0.0155 in² |
| 20 mm² | 0.031 in² |
| 30 mm² | 0.0465 in² |
| 50 mm² | 0.0775 in² |
| 100 mm² | 0.155 in² |
| 1000 mm² | 1.55 in² |
Frequently Asked Questions (FAQ)
How many square inches are in 1 square millimeters?
1 square millimeters (mm²) is exactly 0.00155 square inches (in²).
How do I convert square millimeters to square inches?
Multiply the value in square millimeters by 0.00155 to get the result in square inches. Or use the converter above — type any number and see the result instantly.