How to use this converter
Enter a value in inches to calculate millimeters. Results update as you type. You can swap the direction and choose the displayed precision.
Conversion formula
value × 25.4 = result
Here the starting unit is Inches (in) and the result is in Millimeters (mm). The calculator uses the catalog’s full factors before rounding the displayed result.
Worked examples
- 1 in ≈ 25.4 mm
- 10 in ≈ 254 mm
- 100 in ≈ 2,540 mm
Available length options
Meters (m) · Feet (ft) · Kilometers (km) · Miles (mi) · Centimeters (cm) · Inches (in) · Millimeters (mm) · Yards (yd) · Nautical miles (nmi) · Micrometers (µm) · Nanometers (nm) · Angstroms (Å) · Astronomical units (au) · Light-years (Julian) (ly) · Fathoms (fathom) · Chains (ch) · Furlongs (fur) · Mils (mil)
Frequently asked questions
Why can displayed results differ slightly?
Numeric results are rounded for display. Increase the precision setting to see more digits. Different unit conventions can also produce different results; check the complete unit label.
Can I convert in the opposite direction?
Use the swap control to reverse the selected units or bases.
Related tools
All length units · Browse all converters · cm to inches · mm to inches · meters to feet · km to miles · cm to feet · inches to feet · meters to yards · inches to cm · feet to meters · miles to km · feet to cm · feet to inches · yards to meters