1 inch is equal to 25.4 millimeters.
To convert inches to millimeters, you multiply the inch value by 25.4 because one inch equals exactly 25.4 millimeters. This ensures accurate conversion between these two units of length.
Conversion Tool
Result in mm:
Conversion Formula
The formula to convert inches to millimeters is:
millimeters = inches × 25.4
This works because one inch is defined as exactly 25.4 millimeters. So, multiplying the number of inches by 25.4 converts the length into millimeters. For example, to convert 1 inch:
- Start with 1 inch.
- Multiply by 25.4: 1 × 25.4 = 25.4.
- The result is 25.4 millimeters.
This precise ratio makes unit conversion straightforward and accurate without any rounding for the base value.
Conversion Example
- Convert 3 inches to millimeters:
- Multiply 3 by 25.4.
- 3 × 25.4 = 76.2 mm.
- So, 3 inches equals 76.2 millimeters.
- Convert 0.5 inch to millimeters:
- Multiply 0.5 by 25.4.
- 0.5 × 25.4 = 12.7 mm.
- Hence, half an inch is 12.7 millimeters.
- Convert 10 inches to millimeters:
- Multiply 10 by 25.4.
- 10 × 25.4 = 254 mm.
- Therefore, 10 inches equals 254 millimeters.
- Convert 7.75 inches to millimeters:
- Multiply 7.75 by 25.4.
- 7.75 × 25.4 = 196.85 mm.
- Thus, 7.75 inches is 196.85 millimeters.
Conversion Chart
The chart below show conversions from inches to millimeters, covering values from -24.0 to 26.0 inches. To use, find the inch value and read across to the millimeter equivalent. Negative values indicate lengths in the opposite direction or below reference point.
| Inches | Millimeters (mm) |
|---|---|
| -24.0 | -609.6 |
| -20.0 | -508.0 |
| -16.0 | -406.4 |
| -12.0 | -304.8 |
| -8.0 | -203.2 |
| -4.0 | -101.6 |
| 0.0 | 0.0 |
| 2.0 | 50.8 |
| 4.0 | 101.6 |
| 6.0 | 152.4 |
| 8.0 | 203.2 |
| 10.0 | 254.0 |
| 12.0 | 304.8 |
| 14.0 | 355.6 |
| 16.0 | 406.4 |
| 18.0 | 457.2 |
| 20.0 | 508.0 |
| 22.0 | 558.8 |
| 24.0 | 609.6 |
| 26.0 | 660.4 |
Related Conversion Questions
- How many millimeters are in 1 inch exactly?
- What is the formula to convert 1 inch to mm?
- Is 1 inch always equal to 25.4 millimeters?
- How do I convert 1 inch into millimeters without a calculator?
- Can I convert fractional inches like 1.5 inches to mm easily?
- Why does 1 inch equal 25.4 mm and not a rounded number?
- What’s the difference between converting 1 inch to mm and 2 inches to mm?
Conversion Definitions
Inch: An inch is a unit of length measure used mostly in the United States and the United Kingdom. It equals exactly 25.4 millimeters. An inch is subdivided into 16 smaller parts called sixteenths for precise measurement in many applications like carpentry and engineering.
Millimeter: A millimeter is a metric unit of length equal to one-thousandth of a meter. Millimeters are used worldwide for precise measurements in science, engineering, and manufacturing. It allows very fine measurements smaller than a centimeter or an inch.
Conversion FAQs
Is the inch-to-millimeter conversion exact or approximate?
The conversion from inches to millimeters is exact. One inch equals exactly 25.4 millimeters by international agreement. This eliminates any approximation errors in measurement conversions involving inches and millimeters.
Why is the conversion factor 25.4 and not a round number?
The value 25.4 mm per inch comes from an international agreement standardizing the inch in metric terms. This defined the inch as exactly 25.4 millimeters to unify measurement systems globally. It’s not a rounded number but an exact fixed value.
Can negative inch values be converted to millimeters?
Yes, negative inch values represent lengths or positions in the opposite direction on a scale. Converting negative inches to millimeters uses the same formula but results in negative millimeter values, indicating reversed direction or position.
How precise is the conversion when using decimal inches?
Using decimal inches allows very precise conversion, especially when multiplying by 25.4. The millimeter result can be calculated to as many decimal places as needed, limited only by the input precision and rounding choices in calculations.
Is converting from millimeters back to inches done the same way?
To convert millimeters back to inches, divide the millimeter value by 25.4. This reverses the multiplication used from inches to millimeters, providing the original inch value. The two operations are inverse of each other.