Converting between inches and millimeters (mm) is essential for engineering, manufacturing, and DIY projects. While inches are used in imperial systems, millimeters are the standard metric unit for precise measurements.
Key Conversion: 1 inch = 25.4 millimeters (exact)
Our inches to mm converter helps with:
- Precise inch to mm calculations
- Engineering and manufacturing specs
- Woodworking and metalworking projects
- International measurement conversion
Inches to Millimeters Converter
Type any value in inches to see millimeters equivalent (e.g., 1 inch to mm = 25.4 mm)
Inches to Millimeters Conversion Chart
Common inch to millimeter conversions:
| Inches (in) | Millimeters (mm) | Practical Example |
|---|---|---|
| 1/16" | 1.59 mm | Paperclip wire |
| 1/8" | 3.18 mm | Standard pencil lead |
| 1/4" | 6.35 mm | Pencil diameter |
| 1/2" | 12.7 mm | AA battery diameter |
| 1" | 25.4 mm | Quarter dollar coin |
| 12" | 304.8 mm | Standard ruler length |
Note: 1 millimeter = exactly 0.0393701 inches (international standard)
How to Convert Inches to Millimeters Manually
Conversion Formula
1 inch = 25.4 millimeters
millimeters = inches × 25.4
This exact conversion factor is standardized internationally for all inches to millimeters calculations.
Step-by-Step Example
Start with inches value
Example: 2.5 inches to millimeters
Multiply by 25.4
2.5 × 25.4 = 63.5
Result in millimeters
2.5 in = 63.5 mm
Quick Estimation Method
For rough inches to millimeters conversions:
- 1 in ≈ 25 mm
- 2 in ≈ 50 mm
- 4 in ≈ 100 mm
- Multiply inches by 25 and add half (6 in ≈ 150 + 30 = 180 mm)
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