About the Speed Converter
Speed Converter changes a speed between metres per second, kilometres per hour, miles per hour, knots, feet per second, Mach and the speed of light. Type the speed, choose its unit and every other unit is shown. Use it for road signs abroad, car and bike speeds, wind and sailing, aircraft, sport and physics homework. Factors are exact: 1 mph is 0.44704 m/s and 1 knot is exactly 1.852 km/h.
Updated October 2026
How to use the Speed Converter
- 1Type the a speed you want to convert.
- 2Choose the unit it is in from the From unit list.
- 3Read the result in every other unit straight away.
- 4Press Copy to keep the answer, or change the number to try another.
When you need a a speed converter
Speed Converter changes a speed between metres per second, kilometres per hour, miles per hour, knots, feet per second, Mach and the speed of light. Road speeds are in km/h in most countries and mph in the UK, US and a few others. 100 km/h is about 62 mph, and 60 mph is about 97 km/h. If you drive abroad, a quick check of the sign against this table keeps you safe and within the limit.
Units and what they mean
Mach is not a fixed speed: it depends on the air temperature. This page uses the standard value at sea level and 15 °C, which is 340.29 m/s. At aircraft cruising altitude, where the air is colder, Mach 1 is slower, about 295 m/s.
- Kilometres per hour and miles per hour: road speeds, with 1 mph = 1.609344 km/h
- Knots: speed on water and in the air, one nautical mile per hour
- Metres per second: used in physics and for wind speeds
- Mach: speed relative to sound, about 340.29 m/s at sea level and 15 °C
Tips for accurate results
For sailors and pilots, a knot is convenient because one knot is one nautical mile per hour, and a nautical mile is one minute of latitude. 20 knots is about 37 km/h or 23 mph.
Round only at the end of a calculation. If you convert and then convert again, keep the full number in between so small errors do not add up.
Related conversions
To find a speed from a distance and a time, or the time a trip takes, use the Speed Calculator, and for running speeds the Pace Calculator. Related tools: Speed Calculator, Pace Calculator, Length Converter, Time Converter and Unit Converter.
Features
- 7 units in one list
- Every result shown at once
- Exact factors, no rounding until you read it
- Works with decimals and negative-free values
- Copy button for the answer
- Calculated in your browser, so nothing is uploaded.
Frequently asked questions
How do I convert a speed?
Type the number, pick the unit you start with and read the answer in every other unit below. Each unit is stored as an exact factor of one base unit, so a result is the number times its factor divided by the target unit's factor.
How do I convert mph to km/h?
Multiply by 1.609344. For example 60 mph is about 96.6 km/h.
How fast is a knot?
One nautical mile per hour, which is exactly 1.852 km/h or about 1.151 mph.
What is Mach 1 in km/h?
About 1,225 km/h at sea level and 15 °C. It is lower in colder air.
Is the result exact?
The factors used are the official or standard definitions, so the maths is exact. The page rounds what it shows to about 10 significant digits so numbers stay readable.
Does it work on my phone?
Yes. The page is built for small screens, with large inputs and a list of units you can scroll.
Is anything sent to a server?
No. The conversion is plain arithmetic in your browser, so nothing you type leaves your device.