Square Inches to Square Millimetres Converter
Enter an area in square inches and convert it locally to square millimetres.
A QUICK WALKTHROUGH
How to use this tool
- Enter a finite non-negative area in in².
- Convert using 1 inch = 25.4 mm exactly.
- Read the result in mm².
Exact relationship
The international inch is exactly 25.4 mm; therefore 1 in² = 645.16 mm².
Scope
Area only. This does not validate a part, fit, tolerance, or manufacturing drawing.
GOOD TO KNOW
Common questions
Is the factor exact?
Yes, under the international inch definition.