mm to inches Converter
length converter
Instant conversion. Swap anytime.
CAD, machining, and fabrication tolerance workflows.
Converted value
0.03937in
Calculated from your value and units at 6-decimal precision.
Common pairs
Live conversionExact basis: 1 in = 25.4 mm by definition. Commas and scientific notation are supported (for example 1,234.5 or 1e-3).
Conversion updates automatically as you change value, units, or precision.
Advanced options
Batch conversion
Convert multiple values only when you need them, without crowding the main workflow.
Examples
Conversion details
Formula and exact relation
- 1 mm = 0.03937007874 in
- 1 in = 25.4 mm
Formula form: in = mm × 0.03937007874. Display rounding follows your selected precision and does not change base conversion math.
Context outputs
Nearest 1/32 inch
1/32"
Nearest 1/64 inch
3/64"
Nearest 1/128 inch
5/128"
Quick table (mm → in)
| mm | in |
|---|---|
| 1 | 0.03937 |
| 2 | 0.07874 |
| 5 | 0.19685 |
| 10 | 0.393701 |
| 20 | 0.787402 |
| 25 | 0.984252 |
| 50 | 1.968504 |
| 75 | 2.952756 |
| 100 | 3.937008 |
Common metric hardware sizes (mm → in)
| Millimeters | Decimal inches | Nearest 1/64" |
|---|---|---|
| 0.5 mm | 0.019685 in | 1/64" |
| 1 mm | 0.03937 in | 3/64" |
| 1.5 mm | 0.059055 in | 1/16" |
| 2 mm | 0.07874 in | 5/64" |
| 3 mm | 0.11811 in | 1/8" |
| 4 mm | 0.15748 in | 5/32" |
| 5 mm | 0.19685 in | 13/64" |
| 6 mm | 0.23622 in | 15/64" |
| 8 mm | 0.314961 in | 5/16" |
| 10 mm | 0.393701 in | 25/64" |
| 12 mm | 0.472441 in | 15/32" |
| 16 mm | 0.629921 in | 5/8" |
| 20 mm | 0.787402 in | 25/32" |
| 25 mm | 0.984252 in | 63/64" |
Formula
inches = millimeters / 25.4 - Use 25.4 millimeters per inch as the exact conversion definition.
- Divide millimeter value by 25.4.
- Result is expressed in inches.
Example
Worked example: 50 mm to in
- 1 50 / 25.4 = 1.968503937
- 2 Rounded display = 1.9685
- 3 Unit = inches
50 mm is about 1.9685 inches.
How
- Enter millimeter value in the input field.
- Keep conversion direction as mm to in.
- Read live inches output and copy when needed.
Avoid
- Using 2.54 (cm factor) directly on millimeters without dividing by 10 first.
- Rounding too aggressively for tolerance-critical dimensions.
- Confusing inch fractions with decimal inches.
Table
| Conversion | Result |
|---|---|
| 1 mm to inches | 0.03937 in |
| 5 mm to inches | 0.19685 in |
| 10 mm to inches | 0.39370 in |
| 25.4 mm to inches | 1.00000 in |
| 50 mm to inches | 1.96850 in |
| 100 mm to inches | 3.93701 in |
FAQ
What exact constant is used?
The converter uses 1 inch = 25.4 millimeters exactly.
Can I enter decimal millimeter values?
Yes. Decimal millimeter values are supported and the tool shows 1/32, 1/64, and 1/128 inch approximations for shop use.
Is this suitable for engineering drawings?
Yes, this direction is commonly used for technical drawings and fabrication notes.
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