Inches ↔ Millimeters Converter
Quick, accurate conversions between inches and millimeters. Perfect for engineering, construction, DIY projects, and manufacturing.
Millimeters to Inches: Divide millimeters by 25.4
1 inch = 25.4 millimeters (exact conversion)
| Amount | Millimeter |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 25 in | 635 mm |
| 50 in | 1,270 mm |
| 100 in | 2,540 mm |
| 500 in | 12,700 mm |
| 1,000 in | 25,400 mm |
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Inches to Millimeters Converter: Inches to MM and Back
The Inches to Millimeters Converter is a free online tool for accurate two-way conversion between inches and millimeters. It gives you the formulas, worked examples and instant results as you type or move the slider, which suits engineering, construction, DIY projects and manufacturing. A fraction of an inch can be typed as a decimal, and the chart below lists the common fractions in millimeters.
Quick answer: 1 inch is exactly 25.4 millimeters, so 2 inches is 50.8 mm and 5 inches is 127 mm. To convert millimeters to inches, divide by 25.4.
What Is an Inch?
An inch is a unit of length in the imperial and US customary systems. One inch equals exactly 25.4 millimeters. Inches are commonly used in construction, education, travel and engineering where both metric and imperial measurements are required.
What Is a Millimeter?
A millimeter is a unit of length in the metric system. It is one-thousandth of a meter (0.001 m). Millimeters are widely used in manufacturing, engineering, construction and design projects.
Inches to Millimeters Formula
Examples: 1 inch = 1 × 25.4 = 25.4 mm. 2 inches = 2 × 25.4 = 50.8 mm. 5 inches = 5 × 25.4 = 127 mm.
Millimeters to Inches Formula
Examples: 25.4 mm ÷ 25.4 = 1 inch. 50.8 mm ÷ 25.4 = 2 inches. 127 mm ÷ 25.4 = 5 inches.
Inches to MM Chart
These values are exact, so they match the converter above:
| Inches | Millimeters |
|---|---|
| 0.5 in | 12.7 mm |
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
| 5 in | 127 mm |
| 6 in | 152.4 mm |
| 8 in | 203.2 mm |
| 10 in | 254 mm |
| 12 in | 304.8 mm |
| 24 in | 609.6 mm |
| 36 in | 914.4 mm |
| Millimeters | Inches |
|---|---|
| 1 mm | 0.0394 in |
| 5 mm | 0.1969 in |
| 10 mm | 0.3937 in |
| 25.4 mm | 1 in |
| 50 mm | 1.9685 in |
| 100 mm | 3.937 in |
| 150 mm | 5.9055 in |
| 250 mm | 9.8425 in |
| 500 mm | 19.685 in |
| 1000 mm | 39.3701 in |
Fractions of an Inch in Millimeters
Drill bits, socket sizes, pipes and lumber are often marked in fractions of an inch. To convert a fraction, divide it first, so 3/8 is 0.375, and then multiply by 25.4 to get 9.52 mm. This chart does the work for the common sixteenths:
| Fraction of an inch | Decimal inches | Millimeters |
|---|---|---|
| 1/16 in | 0.0625 | 1.59 mm |
| 1/8 in | 0.125 | 3.17 mm |
| 3/16 in | 0.1875 | 4.76 mm |
| 1/4 in | 0.25 | 6.35 mm |
| 5/16 in | 0.3125 | 7.94 mm |
| 3/8 in | 0.375 | 9.52 mm |
| 1/2 in | 0.5 | 12.7 mm |
| 5/8 in | 0.625 | 15.88 mm |
| 3/4 in | 0.75 | 19.05 mm |
| 7/8 in | 0.875 | 22.22 mm |
| 1 in | 1 | 25.4 mm |
If you need centimeters, the CM to inches converter does that directly, and for feet see the feet to inches converter. The length converter and the unit converter cover every other unit.
Who and Where Is It Used?
Students, teachers, engineers, architects, builders and surveyors use it, along with manufacturers and DIY enthusiasts. It is also handy for 3D printing hobbyists, woodworkers, metalworkers and travelers. It is commonly used in engineering, construction, education, manufacturing and DIY projects where both metric and imperial units are required.
How to Use the Inches to Millimeters Converter
Enter the value
Type a number in the input box, or move the slider. Decimals such as 0.125 work too.
Choose the direction
Select Inches to Millimeters or Millimeters to Inches, or press the swap button to reverse it.
Read the result
Press Convert, or just read the result, which updates automatically as you type.
Use the value
Copy the converted value for your calculations or project, and check the formula box under the tool if you need the rule.