1 inch equals 25.4 millimeters (mm).
To convert 01 inches to mm, multiply the inch value by 25.4. Since 1 inch is defined as exactly 25.4 mm, the result is straightforward and exact.
Conversion Tool
Result in mm:
Conversion Formula
The formula to convert inches to millimeters is:
millimeters = inches × 25.4.
This works because 1 inch is exactly 25.4 mm by international agreement. The conversion multiplies the value in inches by 25.4 to get millimeters in the metric system.
For example, converting 1 inch to mm:
- Start with 1 inch.
- Multiply by 25.4.
- 1 × 25.4 = 25.4 mm.
Conversion Example
- Convert 5 inches to mm:
- Take 5 inches.
- Multiply 5 by 25.4.
- 5 × 25.4 = 127 mm.
- So, 5 inches equals 127 mm.
- Convert 0.75 inches to mm:
- Take 0.75 inches.
- Multiply 0.75 by 25.4.
- 0.75 × 25.4 = 19.05 mm.
- Thus, 0.75 inches equal 19.05 mm.
- Convert 10.5 inches to mm:
- Start with 10.5 inches.
- Multiply 10.5 by 25.4.
- 10.5 × 25.4 = 266.7 mm.
- Therefore, 10.5 inches is 266.7 mm.
- Convert 2.25 inches to mm:
- Take 2.25 inches.
- Multiply 2.25 × 25.4.
- 2.25 × 25.4 = 57.15 mm.
- So 2.25 inches equals 57.15 mm.
- Convert 0.1 inches to mm:
- Start from 0.1 inch.
- Multiply by 25.4.
- 0.1 × 25.4 = 2.54 mm.
- Hence, 0.1 inches is 2.54 mm.
Conversion Chart
| Inches | Millimeters (mm) |
|---|---|
| -24.0 | -609.6 |
| -18.0 | -457.2 |
| -12.0 | -304.8 |
| -6.0 | -152.4 |
| 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 |
The chart shows inches in the left column and the equivalent millimeters in the right column. You can find your inch value, then look across to see the mm conversion. Negative values mean measurements in the opposite direction or below zero.
Related Conversion Questions
- How many millimeters are in 1 inch exactly?
- What is the formula to convert 1 inch to mm?
- Is 1 inch equal to 25 or 25.4 mm?
- How do I convert 1 inch to millimeters without a calculator?
- Why is 1 inch defined as 25.4 millimeters?
- Can I convert 1 inch to mm by multiplying by 2.54?
- What’s the difference between 1 inch and 1 mm in size?
Conversion Definitions
Inches: An inch is a unit of length in the imperial and US customary systems, defined as exactly 25.4 millimeters. It is commonly used in the United States, Canada, and the United Kingdom for measuring smaller distances, such as height, width, and screen sizes.
Millimeters (mm): The millimeter is a unit of length in the metric system equal to one thousandth of a meter. It is used worldwide for precise measurements in engineering, manufacturing, and everyday use, representing small distances with high accuracy.
Conversion FAQs
Can I convert inches to millimeters by multiplying by 2.5 instead of 25.4?
Multiplying by 2.5 is a rough estimate, but it’s not accurate because 1 inch is exactly 25.4 mm, not 2.5 mm. Using 2.5 underestimates the length by a large margin. For precise conversion, always multiply by 25.4.
Why is one inch exactly 25.4 millimeters?
The inch was internationally defined as exactly 25.4 millimeters in 1959 during an agreement between English-speaking countries. This fixed value standardizes measurements between metric and imperial systems, ensuring consistency in manufacturing and trade.
How precise is the conversion from inches to millimeters?
The conversion is exact since one inch equals exactly 25.4 millimeters by definition. Any rounding errors come from decimal precision used in calculations or display, not from the conversion factor itself.
Can negative inches be converted to millimeters?
Yes, negative inch values convert directly to negative millimeters by multiplying by 25.4. This is useful for indicating measurements below a reference point or direction opposite to the positive axis.
Does this conversion apply to inches in all contexts?
This conversion applies to standard inches used in length measurements. However, in some fields like screen resolution, there are other units like pixels per inch, which are unrelated to millimeters directly.