Convert Miles per hour (mph) (mph) to Kilometers per hour (km/h) (kmh)
Category: Speed
1 mph = 1.609344 kmh
High-precision rounding: 6 decimals
How to convert miles per hour (mph) to kilometers per hour (km/h)
We convert by pivoting through the SI base unit for Speed and applying exact factors where applicable.
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Examples
Linear unit conversions use standardized factors; many are exact by definition (e.g., 1 in = 25.4 mm, 1 ft = 0.3048 m).
Common mistakes
- Mixing mph with knots in navigation; 1 kn = 1 nmi/h.
About Speed
Speed combines distance and time. Science favors m/s, drivers see km/h or mph, and navigation uses knots (nautical miles per hour). Context determines the most convenient representation and rounding.
About Miles per hour (mph)
Miles per hour (mph)
Primary speed unit in the US and parts of the UK. Aviation weather occasionally mixes knots and mph in legacy feeds.
History: Based on the international mile; persisted in road regulations and vehicle instrumentation.
About Kilometers per hour (km/h)
Kilometers per hour (km/h)
Road and vehicle speed standard in most of the world. Convert from m/s by multiplying by 3.6.
History: Adopted with metric traffic systems and signage during 20th-century metrication.
Related conversions from mph
- mph → knot Knot (kn)
- mph → mach Mach (sea-level approx.)
- mph → ms Meters per second (m/s)
Related conversions to kmh
- knot → kmh Knot (kn)
- mach → kmh Mach (sea-level approx.)
- ms → kmh Meters per second (m/s)