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Millimeters to Inches (mm to in)
Convert millimeters to inches: 1 mm = 0.0393701 in. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.
Formula
1 mm = 0.0393701 in
inches = millimeters × 0.03937007874 — reverse: millimeters = inches × 25.4
The factor is derived from the SI definitions of both units (base unit: m) as listed in NIST SP 811; results on this page are shown to 6 significant figures, the API returns up to 12.
Worked examples
- 5 mm = 0.19685 in
- 12.5 mm = 0.492126 in
- 100 mm = 3.93701 in
Millimeters to inches conversion table
| Millimeters (mm) | Inches (in) |
|---|---|
| 1 | 0.0393701 |
| 2 | 0.0787402 |
| 3 | 0.11811 |
| 4 | 0.15748 |
| 5 | 0.19685 |
| 6 | 0.23622 |
| 7 | 0.275591 |
| 8 | 0.314961 |
| 9 | 0.354331 |
| 10 | 0.393701 |
| 15 | 0.590551 |
| 20 | 0.787402 |
| 25 | 0.984252 |
| 30 | 1.1811 |
| 40 | 1.5748 |
| 50 | 1.9685 |
| 75 | 2.95276 |
| 100 | 3.93701 |
| 200 | 7.87402 |
| 250 | 9.84252 |
| 500 | 19.685 |
| 1000 | 39.3701 |
FAQ
How many inches are in one millimeter?
1 mm = 0.0393701 in. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.
What is the formula to convert millimeters to inches?
Multiply the value in millimeters by 0.03937007874: inches = millimeters × 0.03937007874. For example, 5 mm = 0.19685 in.
How do I convert inches back to millimeters?
Multiply by the inverse factor 25.4 (millimeters = inches × 25.4), or use the inches-to-millimeters page.
Related conversions
Machine access
- API:
GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=mm&to_unit=in - MCP: server
https://tttkmbb.com/mcp, toolconvert_unitswith{"value":5,"from_unit":"mm","to_unit":"in"} - Markdown: https://tttkmbb.com/conversion/mm-to-inches.md · JSON: https://tttkmbb.com/conversion/mm-to-inches.json (add
?value=for a result) · Units: /api/v1/units?quantity=length - OpenAPI operationId:
convert_units. Freshness:static. Authentication: none.