Speed Converter (mph, km/h, knots, m/s)
Convert mph to km/h, km/h to mph, knots, metres per second, Mach and running pace. Type in either box; pace works as minutes:seconds. Advanced adds swim pace, science units and batch convert.
Type in either box. Pace can be typed as minutes:seconds, like 5:30.
Conversion tables
| mph | km/h |
|---|
| km/h | mph |
|---|
Real-life examples
Tap an example to convert it.
How your speed is converted
Your numbers, step by step. Each speed unit is a fixed number of metres per second; pace is the same thing upside down.
- 1
Your speed
60 mph
- 2
Find the factor
1 mph =
1.609344 km/h - 3
Do the sum
60 × 1.609344 =
96.56064 km/h - 4
Your answer
96.56064 km/h
1 km/h = 0.621371 mph
Read more: the formula, a worked example, pace and Mach
The formula
speed in m/s = your number × metres per second in one of your unit
answer = speed in m/s ÷ metres per second in one of the unit you want
mph to km/h: km/h = mph × 1.609344
km/h to mph: mph = km/h ÷ 1.609344
pace (min per km) = 60 ÷ km/h
Worked example
60 miles per hour in kilometres per hour: 60 × 1.609344 = 96.56064 km/h, about 96.56 km/h. Going back, 96.56064 ÷ 1.609344 = 60 mph.
Why 1.609344? A mile is exactly 1,609.344 m, so one mile an hour is 1.609344 km an hour. Both are "per hour", so only the distance part changes.
Handy speed factors
| 1 of this | Equals |
|---|---|
| Mile per hour | 1.609344 km/h (exact) = 0.44704 m/s (exact) |
| Kilometre per hour | 0.621371 mph = 0.277778 m/s |
| Knot | 1.852 km/h (exact) = 1.150779 mph |
| Metre per second | 3.6 km/h (exact) = 2.236936 mph |
| Foot per second | 0.3048 m/s (exact) = 0.681818 mph |
| Mach 1 (sea level, 15 °C) | 340.294 m/s = 1,225.06 km/h |
Pace and speed
Pace is the time for a set distance, so it goes down as you get faster. That makes it upside down to speed: you divide instead of multiply.
km/h = 60 ÷ (minutes per km)
mph = 60 ÷ (minutes per mile)
minutes per mile = minutes per km × 1.609344
minutes per 100 m = 6 ÷ km/h
So a 5:30 per km pace is 60 ÷ 5.5 = 10.91 km/h, or 8:51 per mile. A swimmer at 2:00 per 100 m is moving at 3 km/h.
About Mach
Mach number is your speed divided by the speed of sound in the air around you. This converter uses the speed of sound in the ICAO Standard Atmosphere at sea level, 15 °C: √(1.4 × 287.05287 × 288.15) = 340.294 m/s. Sound travels slower in colder air, so at 11,000 m (−56.5 °C) Mach 1 is about 295 m/s or 1,062 km/h. For true airspeed at altitude, use the airspeed calculator.
More converters: unit converter, miles to km, feet to metres, area converter, volume converter, pressure, energy, data storage, inches to cm, lbs to kg, oz to grams and Celsius to Fahrenheit. For journey times, use the speed, distance and time calculator.
Factors are exact by definition (international mile and foot, nautical mile of 1,852 m, speed of light 299,792,458 m/s). Speed of sound from the ICAO Standard Atmosphere. Typical speeds in the examples are examples only, not speed limits. Checked 11 October 2026.
Common questions
How do I convert mph to km/h?
Multiply the miles per hour by 1.609344, because a mile is exactly 1,609.344 metres. So 60 mph is 96.56 km/h and 70 mph is 112.65 km/h. For a quick answer in your head, add 60%: 50 mph plus 30 is about 80 km/h (exactly 80.47).
How do I convert km/h to mph?
Divide the kilometres per hour by 1.609344, or multiply by 0.621371. So 100 km/h is 62.14 mph and 120 km/h is 74.56 mph. Type in the right-hand box above, or press the swap button, to go this way. A handy check: 80 km/h is just under 50 mph.
What is a knot?
A knot is one nautical mile per hour. A nautical mile is exactly 1,852 m, so 1 knot is exactly 1.852 km/h, about 1.15078 mph or 0.514 m/s. Pilots and sailors use knots. 100 knots is 185.2 km/h or 115.08 mph.
How fast is Mach 1?
Mach 1 is the speed of sound. In the standard atmosphere at sea level (15 °C) that is 340.294 m/s: 1,225.06 km/h, 761.22 mph or 661.48 knots. Sound is slower in cold air, so at airliner cruising height (about −56.5 °C) Mach 1 is only about 1,062 km/h.
How do I turn running pace into speed?
Divide 60 by your pace in minutes. A pace of 5:00 per km is 60 ÷ 5 = 12 km/h, and 6:00 per mile is 10 mph. To change minutes per km into minutes per mile, multiply by 1.609344: 5:00 per km is about 8:03 per mile.
How do I convert m/s to km/h?
Multiply metres per second by 3.6, because there are 3,600 seconds in an hour and 1,000 metres in a kilometre. So 10 m/s is 36 km/h. To go back, divide km/h by 3.6: 100 km/h is 27.78 m/s. One metre per second is also 2.237 mph.
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