Direct conversion
Convert square millimeter [mm²] to square inch [in²] instantly with formula, examples, chart, and FAQs.
1 square millimeter [mm²] = 0.00155 square inch [in²]
1 square millimeter [mm²] = 0.00155 square inch [in²]
Example: 1 square millimeter [mm²] equals 0.00155 square inch [in²].
Area conversions are derived from squared length relationships, using square metre as the reference unit and fixed factors such as 1 square foot = 0.09290304 square metre.
Displayed results are rounded for readability. The calculator keeps enough precision for everyday use and switches to scientific notation for very large or very small values. Last reviewed: 2026-08-14.
The square millimeter (mm²) is a area unit used to express measurements in this converter.
HistoryThis unit is included because it appears in practical measurement systems, technical references, product specifications, or everyday conversion needs.
Current useUse square millimeter when comparing area values, checking specifications, converting between systems, or preparing quick estimates.
The square inch (in²) is a area unit used to express measurements in this converter.
HistoryThis unit is included because it appears in practical measurement systems, technical references, product specifications, or everyday conversion needs.
Current useUse square inch when comparing area values, checking specifications, converting between systems, or preparing quick estimates.
| square millimeter [mm²] | square inch [in²] |
|---|---|
| 1 | 0.00155 |
| 2 | 0.0031 |
| 5 | 0.00775 |
| 10 | 0.0155 |
| 20 | 0.031 |
| 25 | 0.03875 |
| 50 | 0.0775 |
| 100 | 0.155 |
| 1000 | 1.550003 |
Use this formula: 1 square millimeter [mm²] = 0.00155 square inch [in²] Enter your value in the calculator and the result updates instantly.
1 square millimeter [mm²] equals 0.00155 square inch [in²].
Yes. Use the swap button in the calculator or open the related reverse conversion link when it is listed on this page.