# Miles to Kilometers (mi to km)

> Convert miles to kilometers: 1 mi = 1.60934 km. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

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

## Formula

- `1 mi = 1.60934 km`
- `kilometers = miles × 1.609344`
- Reverse: `miles = kilometers × 0.6213711922`

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 = 8.04672 km
- 12.5 mi = 20.1168 km
- 100 mi = 160.934 km

## Conversion table

| Miles (mi) | Kilometers (km) |
| --- | --- |
| 1 | 1.60934 |
| 2 | 3.21869 |
| 3 | 4.82803 |
| 4 | 6.43738 |
| 5 | 8.04672 |
| 6 | 9.65606 |
| 7 | 11.2654 |
| 8 | 12.8748 |
| 9 | 14.4841 |
| 10 | 16.0934 |
| 15 | 24.1402 |
| 20 | 32.1869 |
| 25 | 40.2336 |
| 30 | 48.2803 |
| 40 | 64.3738 |
| 50 | 80.4672 |
| 75 | 120.701 |
| 100 | 160.934 |
| 200 | 321.869 |
| 250 | 402.336 |
| 500 | 804.672 |
| 1000 | 1609.34 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=mi&to_unit=km` → 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":"km"}`
- 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 kilometers are in one mile?**

1 mi = 1.60934 km. 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 kilometers?**

Multiply the value in miles by 1.609344: kilometers = miles × 1.609344. For example, 5 mi = 8.04672 km.

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

Multiply by the inverse factor 0.6213711922 (miles = kilometers × 0.6213711922), or use the kilometers-to-miles page.

## Related conversions

- [Kilometers to miles](https://tttkmbb.com/conversion/km-to-miles.md) (reverse)
- [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)
- [Meters to Yards](https://tttkmbb.com/conversion/meters-to-yards.md)
- [Yards to Meters](https://tttkmbb.com/conversion/yards-to-meters.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)