Table Of Contents
Square millimeter to square inches Conversion
1 square millimeter (mm²) is equal to 0.0015500031 square inches (in²).
1 mm² = 0.0015500031 in²
or
1 in² = 645.16 mm²
Formula
To convert a area from square millimeter (mm²) to square inches (in²), divide the area in square millimeter by 645.16
a(in²) = a(mm²) / 645.16
Examples:
Convert 1000 square millimeter to square inches:
a(in²) = 1000mm² / 645.16 = 1.5500031 in²
Conversion table
| Square millimeter (mm²) | Square inches (in²) |
|---|---|
| 1 mm² | 0.001550003 in² |
| 2 mm² | 0.003100006 in² |
| 3 mm² | 0.004650009 in² |
| 5 mm² | 0.007750016 in² |
| 10 mm² | 0.015500031 in² |
| 20 mm² | 0.031000062 in² |
| 25 mm² | 0.038750078 in² |
| 50 mm² | 0.077500155 in² |
| 100 mm² | 0.15500031 in² |
| 250 mm² | 0.387500775 in² |
| 500 mm² | 0.77500155 in² |
| 1000 mm² | 1.5500031 in² |
| Square inches (in²) | Square millimeter (mm²) |
|---|---|
| 1 in² | 645.16 mm² |
| 2 in² | 1290.32 mm² |
| 3 in² | 1935.48 mm² |
| 5 in² | 3225.8 mm² |
| 10 in² | 6451.6 mm² |
| 20 in² | 12903.2 mm² |
| 25 in² | 16129 mm² |
| 50 in² | 32258 mm² |
| 100 in² | 64516 mm² |
| 250 in² | 161290 mm² |
| 500 in² | 322580 mm² |
| 1000 in² | 645160 mm² |
Frequently asked questions
How do I convert square millimeter to square inches?
Divide the value in square millimeter by 645.16 to get the result in square inches. For example, 5 mm² ÷ 645.16 = 0.007750016 in².
How many square inches are in 1 square millimeter?
1 square millimeter (mm²) is equal to 0.001550003 square inches (in²).
How do I convert square inches back to square millimeter?
Use the inverse operation: multiply the value in square inches by 645.16 to get the result in square millimeter.
How accurate is the square millimeter to square inches conversion?
The converter multiplies by the conversion factor 645.16 and rounds the result to 9 decimal places by default. You can increase or reduce the precision with the digits option on this page.
Sources
Conversion factors are based on internationally recognised standards:
- BIPM — The International System of Units (SI Brochure, 9th edition)
- NIST Handbook 44, Appendix C — General Tables of Units of Measurement (current edition)
- U.S. Survey Foot: Revised Unit Conversion Factors
- NIST Guide to the SI (SP 811), Appendix B.9: Factors for units listed by kind of quantity or field of science