Unitly

length conversion

How many millimeters are in 1 inch?

Quick answer, a live calculator, and reference values for converting inches to millimeters.

Main answer
1 inch = 25.4 millimeters
Result
1 inch = 25.4 millimeters

Factor: 25.4

There are 25.4 millimeters in 1 inch.

1 inch equals 25.4 millimeters. An inch is a common length unit for everyday sizing, crafts, and travel. A millimeter is another length unit you'll often see on rulers, road signs, and product dimensions. To convert any amount, multiply the number of inches by 25.4 to get millimeters. Results below use standard international conversion factors; round as needed for recipes or construction.
Need the other direction?
Convert millimeters to inches.

Examples

  • 1 inch
    25.4 millimeters
  • 5 inches
    127 millimeters
  • 10 inches
    254 millimeters
  • 100 inches
    2,540 millimeters

Frequently asked questions

How many millimeters are in 1 inch?
There are 25.4 millimeters in 1 inch.
How do I convert inches to millimeters?
Multiply the inches value by 25.4. You can also type any number into the calculator on this page for an instant result.
Is the inches to millimeters conversion exact?
This page uses internationally recognized conversion factors. Displayed values may be rounded for readability—keep extra decimals when a recipe, blueprint, or lab measurement needs higher precision.

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