Use this free online millimeter to inches converter to quickly convert mm to in. Simply enter the value in millimeters, and the tool will instantly display the equivalent length in inches.
| Millimeters | Inches |
|---|
How to Convert Millimeters to Inches
Millimeters belong to the metric system, while inches belong to the imperial system. To convert a value from millimeters to inches, divide the number of millimeters by 25.4.
Formula: in = mm ÷ 25.4
Example: Convert 100 mm to inches. 100 mm ÷ 25.4 = 3.937 in So, 100 millimeters is equal to approximately 3.94 inches.
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.
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.
Millimeter to Inch Relationship
1 mm = 0.03937 in 1 in = 25.4 mm
Because the inch is officially fixed at exactly 25.4 mm, this conversion factor is exact rather than approximate.
Mm to In Conversion Table
| Millimeters (mm) | Inches (in) |
|---|---|
| 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 |
| 500 mm | 19.685 in |
| 1000 mm | 39.37 in |
Solved Examples
Example 1: Convert 50 mm to inches. 50 ÷ 25.4 = 1.9685 in
Example 2: Convert 12 mm to inches. 12 ÷ 25.4 = 0.4724 in
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 0.03937 inches in 1 millimeter.
Divide the mm value by 25.4 to get the equivalent length in inches.
Because millimeters and inches come from different measurement systems (metric and imperial), the conversion involves a decimal factor rather than a whole number.
Inches are commonly used in the United States, Canada, and the United Kingdom, and for screen sizes and construction measurements in those regions.