Convert Inches to Millimeters
1 in = 25.4 mm. Multiply the length in inches by 25.4 to get millimeters.
Inches
in
Millimeters
mm
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How to Convert Inches to Millimeters
Multiply the length in inches by 25.4 to get millimeters.
Common Inches to Millimeters Values
Frequently Asked Questions
How do I convert fractions of an inch to mm?
Convert the fraction to decimal, then multiply by 25.4. For example, 3/16" = 0.1875 × 25.4 = 4.7625 mm.
What is 1/4 inch in mm?
1/4 inch equals exactly 6.35 millimeters.
Why is 25.4 mm per inch exact?
By the 1959 international agreement, the inch was defined as exactly 25.4 mm. This is not a measured approximation — it is the definition itself.
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