Millimeters to Inches Converter
Length conversion workspace
Enter a decimal, fraction or quick calculation — for example 12.5, 3/8 or (12*4)+6.5.
Batch conversionconvert up to 100 values at once
No values yet.
Compare all length units
One input, every supported equivalent. Select any row as the main target.
| Unit | Equivalent | Target action |
|---|---|---|
| Meters m | 1E-3 | |
| Feet ft | 3.28E-3 | |
| Centimeters cm | 0.1 | |
| Millimeters mm | 1 | SourceSource |
| Inches in | 0.04 | TargetSelected |
| Yards yd | 1.09E-3 | |
| Kilometers km | 1E-6 | |
| Miles mi | 6.21E-7 | |
| Nautical Miles nmi | 5.4E-7 |
Use this millimeter-to-inch converter for fastener sizes, manufacturing tolerances, tools, product dimensions and technical drawings.
Curated referenceFormula
inches = millimeters ÷ 25.4
Calculations use the central unit catalog and preserve precision until the result is formatted.
Reference conversions
Fixed reference values use en-US formatting and up to 12 significant digits.
| Input | From | To | Result |
|---|---|---|---|
| 1 | Millimeters | Inches | 0.0393700787402 |
| 2 | Millimeters | Inches | 0.0787401574803 |
| 5 | Millimeters | Inches | 0.196850393701 |
| 10 | Millimeters | Inches | 0.393700787402 |
| 25.4 | Millimeters | Inches | 1 |
| 100 | Millimeters | Inches | 3.93700787402 |
Related length conversions
Curated references with worked examples, formulas and the full interactive converter.
Frequently asked questions
How do I convert millimeters to inches?
Use inches = millimeters ÷ 25.4. Enter a value in the calculator to keep full numeric precision until the result is formatted.
What is 1 mm in in?
1 mm equals 0.0393700787402 in.
Are the displayed results rounded?
The conversion uses the sourced catalog definitions and retains full JavaScript number precision until display formatting is applied.
Accuracy & transparency
Sources & methodology
Calculations keep full numeric precision until display formatting. These references describe the definitions, variants or factors used; links do not imply affiliation.
SI definitions and published coefficients for selected non-SI units.
Reference factors and named variants for commonly used units, including US liquid cooking measures and British stone.
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