Use this free online inches to millimeters converter to quickly convert in to mm. Simply enter the value in inches, and the tool will instantly display the equivalent length in millimeters.
| Inches | Millimeters |
|---|
How to Convert Inches to Millimeters
Inches belong to the imperial system, while millimeters belong to the metric system. To convert a value from inches to millimeters, multiply the number of inches by 25.4.
Formula: mm = in × 25.4
Example: Convert 5 inches to mm. 5 in × 25.4 = 127 mm So, 5 inches is equal to 127 millimeters.
What is an Inch?
An inch (in or ″) is a unit of length in the imperial and US customary systems of measurement. It was officially defined as exactly 25.4 millimeters in 1959. There are 12 inches in a foot and 36 inches in a yard. Inches are mainly used in the United States, Canada, and the United Kingdom, and also for screen sizes worldwide.
What is a Millimeter?
A millimeter (mm) is a unit of length in the metric system, equal to one-thousandth (1/1000) of a meter. It is the smallest unit typically marked on a standard ruler and is widely used where precise measurements are needed, such as engineering, manufacturing, and technical design.
Inch to Millimeter Relationship
1 in = 25.4 mm 1 mm = 0.03937 in
This exact conversion factor makes it easy to switch between imperial and metric measurements for design and manufacturing work.
In to Mm Conversion Table
| Inches (in) | Millimeters (mm) |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 5 in | 127 mm |
| 10 in | 254 mm |
| 12 in | 304.8 mm |
| 20 in | 508 mm |
| 50 in | 1270 mm |
Solved Examples
Example 1: Convert 8 inches to mm. 8 × 25.4 = 203.2 mm
Example 2: Convert 0.5 inches to mm. 0.5 × 25.4 = 12.7 mm
Example 3: Which is greater, 1 inch or 20 mm? 1 in = 25.4 mm, so 1 inch is greater than 20 mm.
Frequently Asked Questions
There are exactly 25.4 millimeters in 1 inch.
Multiply the inch value by 25.4 to get the equivalent length in millimeters.
The inch was officially standardized in 1959 to equal exactly 25.4 millimeters, aligning imperial and metric length measurements.
Millimeters are preferred in most of the world and in fields like engineering and manufacturing that require metric precision.