Most speed units are defined by exact factors, so the conversions are precise rather than approximate: a mile per hour is exactly 0.44704 m/s, a km/h is exactly 0.277778 m/s, a foot per second is 0.3048 m/s and a knot is exactly one nautical mile per hour (0.514444 m/s). Enter a value, choose your from and to units, and the big number updates as you type, with a reference table showing the same speed in all six units at once. Use the swap arrows to reverse the direction. Nothing is uploaded - the math happens on the page.
Speed Converter
Runs entirely in your browser - no upload, no sign-up.
Speed & velocity converter
ResultEnter a speed to convert
How do you convert between speed units?
Pick the unit you have, type a number, and pick the unit you want. This speed converter turns your value into every common unit at once - meters per second, km/h, mph, feet per second, knots and Mach - using exact conversion factors, instantly and entirely in your browser.
How to use
- 1Enter a speed. Type a number in the value field. Decimals are fine - use a dot or a comma, e.g. 100 or 62.5 or 62,5.
- 2Choose the units. Pick the unit you are converting from next to the number, and the unit you want in the To dropdown.
- 3Read every unit at once. The big result shows your target unit; the table below shows the same speed in all six units. Use the swap arrows to reverse it, or Copy result to grab the figure.
Who it's for
- Driving abroad - reading a speed limit in km/h when you think in mph, or the reverse, so you know how fast 100 km/h or 70 mph really is.
- Weather and wind converting a forecast wind speed between km/h, mph, m/s and knots.
- Sailing and aviation working with knots alongside km/h and mph, or checking an aircraft speed against Mach.
- Running and cycling converting a pace or top speed between m/s, km/h and mph.
- Physics and engineering checking a velocity conversion with exact factors instead of a rounded rule of thumb.
FAQ
Is the speed converter free?
Yes - it is 100% free, with no sign-up and no limits. Every conversion runs in your browser and nothing you type is uploaded or stored.
Which speed units does it convert?
Six units: meters per second (m/s), kilometers per hour (km/h), miles per hour (mph), feet per second (ft/s), knots (kn) and Mach. You can convert between any two of them.
How do I convert km/h to mph?
Multiply km/h by 0.621371 to get mph, since 1 mph is 1.609344 km/h. So 100 km/h is about 62.14 mph and 50 km/h is about 31.07 mph. Enter the value and this tool shows it instantly.
How do I convert mph to km/h?
Multiply mph by 1.609344 to get km/h. So 60 mph is 96.56 km/h and 70 mph is 112.65 km/h. A quick mental estimate is to add about 60%.
What is a knot and how fast is it?
A knot is one nautical mile per hour, used at sea and in the air. One knot is 1.852 km/h or about 1.151 mph, so a 20-knot wind is roughly 37 km/h or 23 mph. It is not the same as a mile per hour.
How fast is Mach 1?
Mach is a ratio to the local speed of sound, not a fixed speed. At sea level in standard conditions Mach 1 is about 340.29 m/s (1,225 km/h or 761 mph), but the speed of sound falls with temperature, so Mach 1 is slower at altitude. This tool uses the sea-level value.
Does it work with decimals and commas?
Yes. You can type a dot or a comma as the decimal mark, so both 62.5 and 62,5 are read as the same number. Whitespace is ignored.