0.5 inches equals 12.7 millimeters.
The conversion from inches to millimeters involves multiplying the inch value by 25.4 since one inch equal 25.4 millimeters. So, 0.5 inches times 25.4 gives 12.7 millimeters, which is the metric equivalent.
Conversion Tool
Result in mm:
Conversion Formula
The formula to convert inches (in) to millimeters (mm) is:
millimeters = inches × 25.4
This works because one inch is defined as exactly 25.4 millimeters. When you multiply the length in inches by 25.4, you convert that length into millimeters. The conversion is direct and linear.
Example calculation:
- Start with the value in inches: 0.5 in
- Multiply by 25.4: 0.5 × 25.4 = 12.7
- The result is 12.7 mm
Conversion Example
- Convert 2 inches to millimeters:
- Multiply 2 by 25.4
- 2 × 25.4 = 50.8 mm
- So, 2 in equals 50.8 mm
- Convert 0.75 inches to millimeters:
- Multiply 0.75 × 25.4
- 0.75 × 25.4 = 19.05 mm
- Thus, 0.75 in equals 19.05 mm
- Convert 10.2 inches to millimeters:
- Multiply 10.2 × 25.4
- 10.2 × 25.4 = 259.08 mm
- Therefore, 10.2 in equals 259.08 mm
- Convert 0.1 inches to millimeters:
- Multiply 0.1 × 25.4
- 0.1 × 25.4 = 2.54 mm
- Hence, 0.1 in equals 2.54 mm
Conversion Chart
The chart below shows inch values from -24.5 to 25.5 alongside their millimeter equivalents. You can look up an inch value and directly see its conversion to millimeters without calculation.
| Inches (in) | Millimeters (mm) |
|---|---|
| -24.5 | -24.5 × 25.4 = -622.3 |
| -20.0 | -20 × 25.4 = -508.0 |
| -15.5 | -15.5 × 25.4 = -393.7 |
| -10.0 | -10 × 25.4 = -254.0 |
| -5.5 | -5.5 × 25.4 = -139.7 |
| 0.0 | 0 × 25.4 = 0.0 |
| 5.5 | 5.5 × 25.4 = 139.7 |
| 10.0 | 10 × 25.4 = 254.0 |
| 15.5 | 15.5 × 25.4 = 393.7 |
| 20.0 | 20 × 25.4 = 508.0 |
| 25.5 | 25.5 × 25.4 = 647.7 |
Related Conversion Questions
- How many millimeters are in half an inch?
- What is 0.5 inches converted to mm exactly?
- Is 0.5 inch equal to 12.7 mm or a different value?
- How do you convert 0.5 in to mm without a calculator?
- Why does 0.5 inches equal 12.7 millimeters?
- Can I use 25.4 to convert 0.5 inches to mm?
- What is the formula to convert 0.5 in into millimeters?
Conversion Definitions
In (inch): The inch is a unit of length in the imperial and US customary measurement systems. It equals 1/12 of a foot or 2.54 centimeters exactly. Inches are used primarily in the United States, Canada, and the UK for measuring small distances such as height, width, and screen size.
Mm (millimeter): The millimeter is a metric unit of length equal to one-thousandth of a meter. It is used worldwide for measuring small lengths and distances. It provides precise measurements in fields like engineering, manufacturing, and science where fine accuracy is needed.
Conversion FAQs
Why is the conversion factor exactly 25.4?
The value 25.4 millimeters per inch was established by international agreement in 1959, defining an inch as exactly 25.4 millimeters. This ensures consistency between metric and imperial units, removing any ambiguity that older definitions based on physical standards caused.
Can I convert inches to millimeters by approximation?
Yes, sometimes people use approximate values like 25 or 25.5 to convert inches to millimeters for quick estimates. But such approximations cause small errors, so for accurate work, the exact factor 25.4 should be used.
What happens if I convert negative inches to millimeters?
Negative inches represent lengths in the opposite direction or below zero in a coordinate system. The conversion formula applies the same: multiply the negative inch value by 25.4, resulting in a negative millimeter value. This keeps the sign and magnitude consistent.
Is the conversion the same for fractional inches?
Yes, fractional inches like 1/2 or 3/4 can be converted by first converting the fraction to a decimal, then multiplying by 25.4. For example, 1/2 inch is 0.5 inch, which equals 12.7 mm after conversion.
Does temperature or pressure affect the inch to millimeter conversion?
No, the conversion between inches and millimeters is a fixed mathematical relationship. Temperature or pressure variations do not change the numeric factor, although physical materials may expand or contract with temperature, affecting actual measured lengths.
Last Updated : 03 July, 2025
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Sandeep Bhandari holds a Bachelor of Engineering in Computers from Thapar University (2006). He has 20 years of experience in the technology field. He has a keen interest in various technical fields, including database systems, computer networks, and programming. You can read more about him on his bio page.