Millimeters to Inches Calculator
Convert millimeters to inches (decimal, fraction, and feet+inches) or inches to millimeters. Includes a quick-reference table of 24 common values.
Enter a Value to Convert
Type a number above and the result will appear instantly.
Common MM to Inches Reference
| mm | Inches (decimal) | Inches (fraction) |
|---|---|---|
| 1 | 0.0394 | 3/64 |
| 2 | 0.0787 | 5/64 |
| 3 | 0.1181 | 1/8 |
| 4 | 0.1575 | 5/32 |
| 5 | 0.1969 | 13/64 |
| 6 | 0.2362 | 15/64 |
| 7 | 0.2756 | 9/32 |
| 8 | 0.3150 | 5/16 |
| 9 | 0.3543 | 23/64 |
| 10 | 0.3937 | 25/64 |
| 15 | 0.5906 | 19/32 |
| 20 | 0.7874 | 25/32 |
| 25 | 0.9843 | 63/64 |
| 30 | 1.1811 | 1 3/16 |
| 40 | 1.5748 | 1 37/64 |
| 50 | 1.9685 | 1 31/32 |
| 75 | 2.9528 | 2 61/64 |
| 100 | 3.9370 | 3 15/16 |
| 150 | 5.9055 | 5 29/32 |
| 200 | 7.8740 | 7 7/8 |
| 250 | 9.8425 | 9 27/32 |
| 300 | 11.8110 | 11 13/16 |
| 500 | 19.6850 | 19 11/16 |
| 1000 | 39.3701 | 39 3/8 |
Convert Millimeters to Inches Instantly
Enter any millimeter value and get the result in decimal inches, fractional inches (to the nearest 1/64), and feet plus inches. Swap the direction to convert inches back to millimeters. A quick-reference table covers the most common values.
Why Use This Converter?
Three Output Formats
See your result as a decimal, a fraction rounded to the nearest 1/64 inch, and a feet-plus-inches breakdown — all at once.
Bidirectional Conversion
Switch between mm → inches and inches → mm with one click. The calculator adjusts labels and outputs automatically.
Reference Table
A built-in table of 24 common millimeter values and their inch equivalents saves you from repeated conversions.
Works Offline
Every conversion runs locally in your browser — no internet connection required once the page has loaded, and no data is ever uploaded.
How this Millimeters to Inches Calculator works
This unit converter transforms millimeter measurements into inches across three distinct formats simultaneously: a precise decimal, a rounded fraction, and a combination of feet and inches. By multiplying or dividing by the exact international standard of 25.4 millimeters per inch, the tool ensures high precision for engineering, woodworking, or 3D printing applications.
The fractional output relies on an algorithm that finds the closest matching fraction with a denominator that is a power of 2, capped at a maximum precision of 1/64 of an inch. This matches the standard markings on imperial tape measures and rulers, making it immediately useful for physical fabrication or carpentry where decimal inches are impractical to measure by hand.
You can instantly reverse the calculation by swapping the direction to convert from inches back to millimeters. A built-in reference table displays the conversion for 24 common lengths — from 1mm up to 1000mm — so you can look up standard sizes without needing to type them in. Everything runs offline in the browser once the page has loaded.
How to use this Millimeters to Inches Calculator
Enter a value
Type the millimeter or inch value you want to convert in the input field.
Choose direction
Use mm → inches by default, or click Swap Direction to convert inches to millimeters instead.
Read the result
The result shows as a decimal, a fraction, and feet + inches. Copy any value with one click.
Example Usage
Converting 25.4 millimeters to inches:
Frequently Asked Questions
How many millimeters are in one inch?
How do I convert mm to inches manually?
What does the fraction output represent?
When would I need mm to inches conversion?
Can I convert inches back to millimeters?
Is 10 mm the same as 1 cm?
What is the difference between mm and mil?
How precise is the fractional conversion?
Does this tool work offline?
What are common mm to inches conversions?
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