Miles per hour to Kilometers per hour Converter
1 mph equals 1.609344 km/h, and 1 km/h equals 0.62137119 mph. Enter a value in either box to convert miles per hour to kilometers per hour and back. Formula: m/s = value x factor (1 mph = 0.44704 m/s exactly; 1 knot = 1852/3600 m/s; 1 km/h = 1/3.6 m/s).
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1 mph = 1.609344 km/h
Approximate: Mach depends on air temperature and altitude. This tool uses the International Standard Atmosphere value at sea level (340.294 m/s), so treat Mach results as approximate.
Results shown are estimates for informational purposes only. Nothing on CalcFlow is financial, tax, legal, or medical advice. Always consult a qualified professional before making important decisions.
Miles per hour to Kilometers per hour Conversion Table
| Miles per hour | Kilometers per hour |
|---|---|
| 1 mph | 1.609344 km/h |
| 5 mph | 8.04672 km/h |
| 10 mph | 16.09344 km/h |
| 20 mph | 32.18688 km/h |
| 30 mph | 48.28032 km/h |
| 50 mph | 80.4672 km/h |
| 60 mph | 96.56064 km/h |
| 100 mph | 160.9344 km/h |
| 120 mph | 193.12128 km/h |
Kilometers per hour to Miles per hour Conversion Table
| Kilometers per hour | Miles per hour |
|---|---|
| 1 km/h | 0.62137119 mph |
| 5 km/h | 3.106856 mph |
| 10 km/h | 6.2137119 mph |
| 20 km/h | 12.427424 mph |
| 30 km/h | 18.641136 mph |
| 50 km/h | 31.06856 mph |
| 60 km/h | 37.282272 mph |
| 100 km/h | 62.137119 mph |
| 120 km/h | 74.564543 mph |
Worked example: 10 mph = 16.09344 km/h. A speed limit of 100 km/h is 100 x 0.621371 = 62.14 mph. A 20 knot wind is 20 x 1.852 = 37.04 km/h.
Need other units? Open the full Speed Converter.
Popular Speed Conversions
Formula
m/s = value x factor (1 mph = 0.44704 m/s exactly; 1 knot = 1852/3600 m/s; 1 km/h = 1/3.6 m/s)Understanding Speed Conversion
Speed is distance divided by time, so speed units pair a length unit with a time unit. Road speeds are in kilometers per hour in most countries and miles per hour in the United States and UK. Ships and aircraft use knots, a nautical mile per hour. Mach compares speed with the speed of sound, which changes with temperature, so a fixed sea-level reference is used here.
Tips and Best Practices
- 1To convert km/h to mph multiply by 0.6214; mph to km/h multiply by 1.6093.
- 2To convert m/s to km/h multiply by 3.6.
- 3One knot is about 1.15 mph or 1.852 km/h.
Real-World Example
A speed limit of 100 km/h is 100 x 0.621371 = 62.14 mph. A 20 knot wind is 20 x 1.852 = 37.04 km/h.
Common Mistakes to Avoid
- Dividing by 3.6 when you should multiply (m/s to km/h multiplies, km/h to m/s divides).
- Treating a knot as a unit of distance; it is already per hour, so "knots per hour" is wrong.
- Using Mach 1 as a constant 1,235 km/h; it varies with altitude and temperature.
How to Use
- Type a number in the Miles per hour box.
- The Kilometers per hour result appears instantly; you can also edit the Kilometers per hour box to convert backwards.
- Use the swap button to reverse the direction and Copy result to copy the answer.
Frequently Asked Questions
How many kilometers per hour are in 1 mph?
How many miles per hour are in 1 km/h?
What is the formula to convert miles per hour to kilometers per hour?
How do I convert m/s to km/h?
Sources: NIST SP 811 (mile, knot); ISO 2533 International Standard Atmosphere (speed of sound 340.294 m/s at sea level, 15 C).