# Miles per hour to Kilometers per hour (mph to km/h)

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

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

## Formula

- `1 mph = 1.60934 km/h`
- `kilometers per hour = miles per hour × 1.609344`
- Reverse: `miles per hour = kilometers per hour × 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 mph = 8.04672 km/h
- 12.5 mph = 20.1168 km/h
- 100 mph = 160.934 km/h

## Conversion table

| Miles per hour (mph) | Kilometers per hour (km/h) |
| --- | --- |
| 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=mph&to_unit=km%2Fh` → 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":"mph","to_unit":"km/h"}`
- All speed units: https://tttkmbb.com/api/v1/units?quantity=speed · full converter: [Speed Converter](https://tttkmbb.com/conversion/speed.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many kilometers per hour are in one mile per hour?**

1 mph = 1.60934 km/h. 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 per hour to kilometers per hour?**

Multiply the value in miles per hour by 1.609344: kilometers per hour = miles per hour × 1.609344. For example, 5 mph = 8.04672 km/h.

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

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

## Related conversions

- [Kilometers per hour to miles per hour](https://tttkmbb.com/conversion/kmh-to-mph.md) (reverse)
- [Meters per second to Kilometers per hour](https://tttkmbb.com/conversion/meters-per-second-to-kmh.md)
- [Kilometers per hour to Meters per second](https://tttkmbb.com/conversion/kmh-to-meters-per-second.md)
- [Meters per second to Miles per hour](https://tttkmbb.com/conversion/meters-per-second-to-mph.md)
- [Miles per hour to Meters per second](https://tttkmbb.com/conversion/mph-to-meters-per-second.md)
- [Knots to Kilometers per hour](https://tttkmbb.com/conversion/knots-to-kmh.md)
- [Kilometers per hour to Knots](https://tttkmbb.com/conversion/kmh-to-knots.md)
- [Knots to Miles per hour](https://tttkmbb.com/conversion/knots-to-mph.md)
- [Miles per hour to Knots](https://tttkmbb.com/conversion/mph-to-knots.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)