# Miles to Nautical miles (mi to nmi)

> Convert miles to nautical miles: 1 mi = 0.868976 nmi. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `miles-to-nautical-miles` · Quantity: Length (`length`, base unit m) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/miles-to-nautical-miles · This document: https://tttkmbb.com/conversion/miles-to-nautical-miles.md · JSON: https://tttkmbb.com/conversion/miles-to-nautical-miles.json (add `?value=` for a result)

## Formula

- `1 mi = 0.868976 nmi`
- `nautical miles = miles × 0.8689762419`
- Reverse: `miles = nautical miles × 1.150779448`

The factor follows from the SI definitions of both units (NIST SP 811); values below are rounded to 6 significant figures, the API returns up to 12.

## Worked examples

- 5 mi = 4.34488 nmi
- 12.5 mi = 10.8622 nmi
- 100 mi = 86.8976 nmi

## Conversion table

| Miles (mi) | Nautical miles (nmi) |
| --- | --- |
| 1 | 0.868976 |
| 2 | 1.73795 |
| 3 | 2.60693 |
| 4 | 3.4759 |
| 5 | 4.34488 |
| 6 | 5.21386 |
| 7 | 6.08283 |
| 8 | 6.95181 |
| 9 | 7.82079 |
| 10 | 8.68976 |
| 15 | 13.0346 |
| 20 | 17.3795 |
| 25 | 21.7244 |
| 30 | 26.0693 |
| 40 | 34.759 |
| 50 | 43.4488 |
| 75 | 65.1732 |
| 100 | 86.8976 |
| 200 | 173.795 |
| 250 | 217.244 |
| 500 | 434.488 |
| 1000 | 868.976 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=mi&to_unit=nmi` → unified JSON envelope with `result.values.result`, `formula`, `factor`, `sources`, `freshness`
- MCP: server `https://tttkmbb.com/mcp`, tool `convert_units` with `{"value":5,"from_unit":"mi","to_unit":"nmi"}`
- All length units: https://tttkmbb.com/api/v1/units?quantity=length · full converter: [Length Converter](https://tttkmbb.com/conversion/length.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many nautical miles are in one mile?**

1 mi = 0.868976 nmi. 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 miles to nautical miles?**

Multiply the value in miles by 0.8689762419: nautical miles = miles × 0.8689762419. For example, 5 mi = 4.34488 nmi.

**How do I convert nautical miles back to miles?**

Multiply by the inverse factor 1.150779448 (miles = nautical miles × 1.150779448), or use the nautical miles-to-miles page.

## Related conversions

- [Nautical miles to miles](https://tttkmbb.com/conversion/nautical-miles-to-miles.md) (reverse)
- [Kilometers to Miles](https://tttkmbb.com/conversion/km-to-miles.md)
- [Miles to Kilometers](https://tttkmbb.com/conversion/miles-to-km.md)
- [Meters to Feet](https://tttkmbb.com/conversion/meters-to-feet.md)
- [Feet to Meters](https://tttkmbb.com/conversion/feet-to-meters.md)
- [Centimeters to Inches](https://tttkmbb.com/conversion/cm-to-inches.md)
- [Inches to Centimeters](https://tttkmbb.com/conversion/inches-to-cm.md)
- [Millimeters to Inches](https://tttkmbb.com/conversion/mm-to-inches.md)
- [Inches to Millimeters](https://tttkmbb.com/conversion/inches-to-mm.md)

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-24)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-24)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (reference, retrieved 2026-09-24)