Speed Converter
Type a number once — see it in every speed unit instantly.
Enter a number to see it in every speed unit.
All speed units at once
| Unit | Value |
|---|---|
| Meters per second (m/s) | — |
| Kilometers per hour (km/h) | — |
| Miles per hour (mph) | — |
| Feet per second (ft/s) | — |
| Knots (kn)1 nautical mile per hour = 1.852 km/h | — |
| Mach (sea level, 15°C)Reference: sea level, 15°C (≈340.29 m/s) | — |
| Pace (min/km) | — |
| Pace (min/mile) | — |
Understanding speed unit conversion
Speed is distance over time, but the world measures it in stubbornly different units: road signs in km/h or mph, aviation and sailing in knots, physics in metres per second, and aerospace in Mach. This converter treats metres per second (m/s), the SI unit, as the hidden base — every value is turned into m/s and then out to the unit you want, which keeps results consistent no matter which pair you compare.
Where the conversion factors come from
All of these follow from fixed definitions. One km/h is one kilometre (1000 m) over 3600 seconds, so 1 m/s = 3.6 km/h exactly. A mile is 1609.344 m, giving 1 mph = 0.44704 m/s. A knot is one nautical mile (1852 m) per hour, so 1 knot = 1.852 km/h exactly. Mach is different in kind: it is a ratio to the local speed of sound, about 340.29 m/s at sea level and 15 °C.
Conversion table (based on 1 m/s)
| Unit | 1 of this unit = m/s | 1 m/s = this many |
|---|---|---|
| km/h | 0.27778 | 3.60000 |
| mph | 0.44704 | 2.23694 |
| knot | 0.51444 | 1.94384 |
| ft/s | 0.30480 | 3.28084 |
| Mach (sea level) | 340.29 | 0.00294 |
Everyday reference speeds
Putting numbers to familiar motion makes the units concrete. A brisk walk is about 1.4 m/s (5 km/h, 3.1 mph). A cyclist cruises near 5.5 m/s (20 km/h). Highway traffic at 100 km/h is 27.8 m/s, or 62 mph. A commercial airliner cruises around 250 m/s (900 km/h, 486 knots, Mach 0.73), and the speed of sound at sea level is roughly 340 m/s. Once a value is in m/s you can reach any of the others with a single multiply, which is exactly what this converter does under the hood.
Common mistakes and edge cases
- Mixing knots and km/h: a knot is about 1.85 km/h, not 1. A "20 knot" wind is roughly 37 km/h.
- Reading mph as km/h: the two differ by about 1.6 times, so 30 mph is about 48 km/h — a large gap at any speed.
- Treating Mach as fixed: the speed of sound falls with temperature, so Mach 1 high in the stratosphere is a lower true speed than Mach 1 at the runway. This tool uses the sea-level, 15 °C reference.
- Feet per second shows up in ballistics and some engineering; multiply ft/s by 0.3048 to reach m/s.
Every conversion here is an exact ratio between defined units, so the only rounding happens in the final displayed digits.
Sources & further reading
Frequently asked questions
How do I convert km/h to mph (and mph to km/h)?
To convert km/h to mph, multiply by 0.621371 — so 1 km/h = 0.6213711922 mph and 100 km/h ≈ 62.14 mph. Going the other way, multiply mph by 1.609344, so 1 mph = 1.609344 km/h and 60 mph ≈ 96.56 km/h. This converter does both directions at once: type a number, pick km/h → mph (or swap), and read every unit instantly.
What is a knot, and how does it relate to km/h and mph?
A knot is one nautical mile per hour, used in aviation and sailing. One knot equals exactly 1.852 km/h, which is about 1.15078 mph or 0.514444 m/s. So 10 knots ≈ 18.52 km/h ≈ 11.51 mph. Because a nautical mile is based on the Earth's circumference, knots are handy for navigation across latitude and longitude.
How do I convert m/s to km/h, and what is Mach?
To convert meters per second to km/h, multiply by 3.6 — so 1 m/s = 3.6 km/h and 10 m/s = 36 km/h. Feet per second (ft/s) uses a factor of 0.3048 m/s. Mach is the ratio to the speed of sound; this tool uses the standard sea-level value at 15°C, where Mach 1 ≈ 340.29 m/s ≈ 1225 km/h. The real speed of sound changes with altitude and temperature, so Mach here is a reference figure.
How precise are the results?
Every conversion keeps up to 10 significant figures, then trailing zeros are trimmed for readability. Very large or very small numbers (roughly 1e15 and above, or below 1e-9) switch to scientific notation, so nothing is silently rounded away to zero. The km/h, mph, ft/s and knot factors are exact by definition; only Mach depends on the chosen air condition.
Is my input sent to a server?
No. This speed converter runs entirely in your browser — the number you type is never uploaded anywhere. The only thing saved is your last chosen unit pair (for example km/h → mph), kept in your browser's local storage so it is ready next time. The value itself is not stored, and there are no accounts or trackers.