Length and Area
mm²toin²
Convert square millimetres (mm²) to square inches (in²).
Factor1 mm² = 0.001550003 in²
Converter
mm²
Accepts numbers or expressions, e.g. 150 + 14.7
Result
in²
Rendered to 6 significant figures.
Formula
Formula
in² = mm² × 0.001550003
Multiply any value in square millimetres by 0.001550003 to obtain the value in square inches.
Worked example
Convert 1000 mm² to in².
- 01Start with 1000 mm².
- 02Multiply by the conversion factor: 1000 × 0.001550003 = 1.55 in².
Result1000 mm² = 1.55 in²
Conversion table
| mm² | in² |
|---|---|
| 1 | 0.00155 |
| 2 | 0.0031 |
| 5 | 0.00775 |
| 10 | 0.0155 |
| 20 | 0.031 |
| 50 | 0.0775 |
| 100 | 0.155 |
| 200 | 0.31 |
| 500 | 0.775 |
| 1000 | 1.55 |
Reference values rounded to 5 significant figures for display.
FAQ
What is the conversion factor from mm² to in²?
1 mm² equals 0.001550003 in². To convert, multiply the value in square millimetres by 0.001550003.
How do I convert 1 mm² to in²?
1 mm² = 0.00155 in². For any value, multiply by 0.001550003.
How do I convert in² back to mm²?
Divide by the same factor — or equivalently, multiply by 645.16. So 1 in² = 645.16 mm².
When would I need to convert square millimetre to square inch?
Area conversions are common in heat-exchanger surface area, site layout, and land-use planning where imperial and metric conventions mix.
Is the conversion exact?
The factor shown is precise to at least 7 significant figures. For most process-engineering work this is far better than instrument accuracy. For metrology or trade applications, refer to the relevant national standard (NIST, BIPM, ISO 80000).