Square Millimeters to Square Inches converter (mm² to in²)
Convert Square Millimeters (mm²) to Square Inches (in²) with this free calculator. Type a value, press Convert, and the page applies the same factor shown in the formula below — no rounded shortcut, and nothing is stored on a server.
Square Inches to Square Millimeters (in² to mm²) ►
How to convert Square Millimeters to Square Inches
1 square millimeter (mm²) is equal to 0.00155 square inches (in²).
in² = mm² × 0.0015500031
Multiply the area in square millimeters by 0.0015500031:
Example: Convert 645.16 mm² to in²:
in² = 645.16 × 0.00155 = 1 in²
What is a Square Millimeters?
The Square Millimeters (mm²) is the starting or target unit on this page. Use the calculator above to convert values without looking up the factor by hand.
What is a Square Inches?
The Square Inches (in²) is the starting or target unit on this page. Use the calculator above to convert values without looking up the factor by hand.
This page converts area from Square Millimeters into Square Inches. One mm² equals 0.001550003 in².
Square Millimeters to Square Inches conversion table
Common mm² values and the matching in² result, calculated with the same factor as the widget. Highlight a nearby row if you want a quick check without entering a number.
| Square Millimeters (mm²) | Square Inches (in²) |
|---|---|
| 100 mm² | 0.15500031 in² |
| 500 mm² | 0.77500155 in² |
| 645 mm² | 0.999751999 in² |
| 1000 mm² | 1.5500031 in² |
| 5000 mm² | 7.7500155 in² |
| 10000 mm² | 15.500031 in² |
How this calculator works
The form on this page is a Square Millimeters-to-Square Inches converter. After you enter a number, JavaScript multiplies or rearranges it with the published conversion factor and writes the in² result in the output box. The step-by-step panel repeats the arithmetic so you can copy it into homework or a spreadsheet.
Reviewed by Hamsen, founder of GigaTables and a biology engineer. See the about page for how formulas are checked before a tool is published.
FAQ
How many in² are in 1 mm²?
1 mm² = 0.001550003 in².
How do I convert Square Millimeters to Square Inches?
Multiply the area in square millimeters by 0.0015500031:
Is this mm² to in² converter free?
Yes. GigaTables calculators are free to use in a browser. You do not need an account, and the values you type are not uploaded.