0.25 inch equals 6.35 millimeters.
To convert inches to millimeters, you multiply the inch value by 25.4 because one inch is exactly 25.4 millimeters. Therefore, 0.25 inch times 25.4 gives the result in millimeters.
Conversion Tool
Result in mm:
Conversion Formula
The formula to convert inch to millimeter is:
millimeters = inches × 25.4
This works because one inch is defined as exactly 25.4 millimeters. Multiplying the inch value by 25.4 converts it into millimeters. No matter the inch value, this formula applies directly.
Example:
- Start with 0.25 inches.
- Multiply 0.25 by 25.4.
- 0.25 × 25.4 = 6.35 millimeters.
Conversion Example
- Example: Convert 2.5 inches to millimeters
- Take the value 2.5 inches.
- Multiply 2.5 × 25.4.
- Result is 63.5 millimeters.
- Example: Convert 0.1 inch to millimeters
- Start with 0.1 inch.
- Multiply 0.1 × 25.4.
- Result equals 2.54 millimeters.
- Example: Convert 5 inches to millimeters
- Begin with 5 inches.
- Multiply 5 × 25.4.
- Result is 127 millimeters.
- Example: Convert 0.75 inch to millimeters
- Use 0.75 inch.
- Multiply 0.75 × 25.4.
- Result equals 19.05 millimeters.
Conversion Chart
The table below shows inch values from -24.8 to 25.2 with their millimeter equivalents. To use it, find the inch value in the first column and read across to see the corresponding millimeter value.
| Inch | Millimeters (mm) |
|---|---|
| -24.8 | -629.92 |
| -20.0 | -508.00 |
| -15.5 | -393.70 |
| -10.1 | -256.54 |
| -5.6 | -142.24 |
| -1.0 | -25.40 |
| 0.0 | 0.00 |
| 1.2 | 30.48 |
| 5.5 | 139.70 |
| 10.0 | 254.00 |
| 15.0 | 381.00 |
| 20.5 | 520.70 |
| 25.2 | 640.08 |
Related Conversion Questions
- How many millimeters is 0.25 inch exactly?
- What is the formula to convert 0.25 inch into mm?
- Is 0.25 inch bigger or smaller than 6 mm?
- How to convert 0.25 inch to millimeters without a calculator?
- What is 0.25 inch in mm rounded to two decimal places?
- Why does 0.25 inch equal 6.35 mm?
- How many mm make up 0.25 inch in metric?
Conversion Definitions
Inch: An inch is a unit of length in the imperial and U.S. customary system, precisely defined as 1/12 of a foot or exactly 25.4 millimeters. It is used primarily in the United States, Canada, and the United Kingdom for measuring small distances, thicknesses, and screen sizes.
Millimeter (mm): Millimeter is a metric unit of length, equal to one-thousandth of a meter. It is used worldwide as part of the metric system for measuring small dimensions such as thickness, diameter, and lengths in science, engineering, and everyday life.
Conversion FAQs
Can the conversion factor between inch and millimeter ever change?
No, the conversion factor from inch to millimeter is fixed by international agreement to 25.4. This exact value has been used since 1959, so any conversion between inches and millimeters should always use this number for accuracy.
Why is 1 inch equal to exactly 25.4 millimeters?
The inch was defined to be exactly 25.4 millimeters to create consistency between the imperial and metric systems. Before this, inch lengths varied slightly in different countries. The exact definition helps avoid confusion in manufacturing and international trade.
Does converting negative inch values to millimeters work the same way?
Yes, negative values in inches represent length in opposite directions or below zero in measurement, and converting them to millimeters involves the same multiplication by 25.4, resulting in negative millimeter values correspondingly.
How precise is the conversion from inch to millimeter in practical use?
The conversion factor 25.4 is exact, but practical precision depends on the measuring tools and rounding. For most applications, rounding to four decimal places, like 6.3500 mm for 0.25 inch, provides more than enough accuracy.
Are there any tools besides multiplying by 25.4 for converting inches to millimeters?
Multiplying by 25.4 is the direct way to convert, but there are online converters and calculator tools available that automate this process. The underlying calculation remains the same, just done by software for convenience.