Speed conversion
Miles per hour to Kilometres per hour (mph to km/h)
Read a miles-per-hour value in kilometres per hour, for example when comparing a US or UK road speed with a metric dashboard.
1 mph ≈ 1.6093 km/h — the calculator keeps the stored factor; this summary may be rounded.
A road-speed reference of 55 mph
- Starting measurement
- 55 mph
- Converted value (rounded if needed)
- 88.5139 km/h
Round only for the comparison you need. Keep the posted number and its original unit as the reference rather than treating a rounded conversion as a new limit.
Miles per hour to Kilometres per hour conversion chart
| miles per hour | kilometres per hour |
|---|---|
| 5 mph | 8.0467 km/h |
| 10 mph | 16.0934 km/h |
| 20 mph | 32.1869 km/h |
| 25 mph | 40.2336 km/h |
| 30 mph | 48.2803 km/h |
| 40 mph | 64.3738 km/h |
| 50 mph | 80.4672 km/h |
| 55 mph | 88.5139 km/h |
| 60 mph | 96.5606 km/h |
| 65 mph | 104.607 km/h |
| 70 mph | 112.654 km/h |
| 75 mph | 120.701 km/h |
| 80 mph | 128.748 km/h |
| 100 mph | 160.934 km/h |
How to convert by hand
Reference relationship (display may be rounded)
1 mph = 1.609344 km/h
- Multiply the amount in miles per hour by the number of kilometres per hour per unit.
- Use the calculator for the stored precision; copying a short displayed factor introduces extra rounding.
- Round the result to suit your measurement, after completing the calculation.
Related conversions
About miles per hour and kilometres per hour
A converted speed describes the same motion in a different unit. Keep speed separate from pace, which is time per distance, and from travel time, which also needs a distance.
Mile per hour
US / ImperialA speed covering one land mile in one hour if maintained. Miles per hour use land miles, unlike knots.
Commonly used for: US and UK road speeds and speed comparisons in forecasts.
Kilometre per hour
MetricA speed covering one kilometre in one hour if maintained. Converting it changes the unit, not the journey time.
Commonly used for: Metric speedometers, road signs and cycling speeds.
Questions
Why do the number of kilometres per hour and miles per hour differ?
A land mile is longer than a kilometre, so the same motion covers more kilometres than miles in an hour. The vehicle has not changed speed; only the unit has changed.
How do I convert kilometres per hour back to miles per hour?
Enter the value in the kilometres per hour field above to work backwards, or open the Kilometres per hour to Miles per hour converter. This uses the stored factors rather than dividing by a rounded number copied from the chart.
Why might the chart and calculator show different decimal places?
The chart uses a compact rounded display. The editable calculator can show up to six decimal places and uses the factors or temperature formulas stored in the library. More displayed digits do not make the original measurement more precise.
Precision and source
The calculator uses stored conversion factors and temperature formulas, then rounds the result for display. A short decimal in a chart is not a claim of exactness. For a calculation with several steps, keep as much precision as the original measurement supports and round at the end.
Reference: NIST SP 811 conversion factors. Its alphabetical tables distinguish unit variants and temperature readings from intervals. Published by ToolsNow. Report a conversion problem.
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