mph vs km/h
Differences, use cases, and when to use each
Miles per hour (mph) is the speed unit used in the US and UK road systems. Kilometers per hour (km/h) is the metric speed unit used by most of the world. 1 mph = 1.609 km/h.
Quick Comparison
| Feature | mph | km/h |
|---|---|---|
| System | Imperial | Metric (SI) |
| 1 Unit = | 1.609 km/h | 0.621 mph |
| Usage | US, UK road signs | Most of the world, aviation (kph for ground) |
| Common Speeds | 60 mph highway, 30 mph urban | 100 km/h highway, 50 km/h urban |
| Sports | US sports broadcasts | International sports broadcasts |
When to Use Each
When to Use mph
Use mph for US and UK audiences in road contexts — speed limits, car specifications marketed in the US/UK, and American sports broadcasts.
When to Use km/h
Use km/h for international audiences, all scientific contexts, and any content consumed outside the US and UK. Most GPS devices and international weather apps use km/h.
Pros & Cons
mph
Standard for US/UK roads
Familiar for American audiences
Only used in US and UK for roads
km/h
International standard
Used by almost all countries globally
Scientific standard
Less familiar to American audiences
Verdict
1 mph ≈ 1.6 km/h. US and UK drivers think in mph; everyone else thinks in km/h. GPS devices typically support both. International car specs list both units.