🚀 Speed Converter
By ToolNimba Editorial Team · Updated 2026-06-19
Type in any box and every other unit updates instantly.
This speed converter changes a value between metres per second, kilometres per hour, miles per hour, knots, and feet per second. Type a number into any box and every other unit updates at once, so you can read off the equivalent speed without doing the maths. It is handy for travel, sailing, weather, running, and any time a speed is quoted in a unit you are not used to.
What is the Speed Converter?
Speed measures how far something travels in a given amount of time, so every speed unit is just a distance unit divided by a time unit. Metres per second (m/s) is the scientific (SI) unit and the cleanest one to convert through, because every other speed can be turned into m/s with a single multiplication and then back out into any other unit. That is exactly how this tool works internally: whatever you type is first converted to m/s, then to all the other units.
The everyday road units are kilometres per hour (km/h), used for speed limits in most of the world, and miles per hour (mph), used in the United States and the United Kingdom. They differ only by the size of the distance unit, since a mile is about 1.609 kilometres. Knots are nautical miles per hour and are standard in shipping and aviation, where one knot equals one nautical mile (1,852 metres) per hour. Feet per second (ft/s) shows up in physics problems, ballistics, and some engineering work.
The conversions here use exact, internationally agreed factors rather than rounded approximations. One mph is defined as exactly 0.44704 m/s, one knot as exactly 0.514444 m/s (1,852 metres in 3,600 seconds), one km/h as exactly 0.277778 m/s (1,000 metres in 3,600 seconds), and one foot as exactly 0.3048 metres. Using the exact factors means the results stay accurate even for large speeds, so a converted figure will match what you get from official sources rather than drifting by a fraction.
When to use it
- Reading a foreign speed limit sign in km/h when you are used to mph (or the other way round).
- Translating a wind speed or boat speed given in knots into mph or km/h for a forecast or trip.
- Checking a physics or engineering answer expressed in m/s or ft/s against a more familiar unit.
How to use the Speed Converter
- Pick the unit you already know your speed in (for example mph).
- Type the number into that unit's box.
- Read the equivalent value from every other box, which updates instantly.
- Clear the box or type a new number to convert a different speed.
Formula & method
Worked examples
Convert 60 mph to km/h.
- 60 mph to m/s: 60 × 0.44704 = 26.8224 m/s
- 26.8224 m/s to km/h: 26.8224 ÷ 0.277778 = 96.56 km/h
Result: 60 mph ≈ 96.56 km/h
Convert 100 km/h to mph.
- 100 km/h to m/s: 100 × 0.277778 = 27.7778 m/s
- 27.7778 m/s to mph: 27.7778 ÷ 0.44704 = 62.14 mph
Result: 100 km/h ≈ 62.14 mph
Convert 20 knots to mph and km/h.
- 20 knots to m/s: 20 × 0.514444 = 10.28888 m/s
- to mph: 10.28888 ÷ 0.44704 = 23.02 mph
- to km/h: 10.28888 ÷ 0.277778 = 37.04 km/h
Result: 20 knots ≈ 23.02 mph ≈ 37.04 km/h
Conversion factors to metres per second (exact)
| Unit | 1 unit in m/s | Note |
|---|---|---|
| Metre per second (m/s) | 1 | SI base unit for speed |
| Kilometre per hour (km/h) | 0.277778 | 1000 m ÷ 3600 s |
| Mile per hour (mph) | 0.44704 | 1609.344 m ÷ 3600 s |
| Knot (kn) | 0.514444 | 1852 m ÷ 3600 s |
| Foot per second (ft/s) | 0.3048 | 1 foot = 0.3048 m |
Common speeds across units (rounded)
| mph | km/h | knots | m/s |
|---|---|---|---|
| 10 | 16.09 | 8.69 | 4.47 |
| 30 | 48.28 | 26.07 | 13.41 |
| 60 | 96.56 | 52.14 | 26.82 |
| 70 | 112.65 | 60.83 | 31.29 |
| 100 | 160.93 | 86.90 | 44.70 |
Common mistakes to avoid
- Confusing knots with mph. A knot is faster than a mile per hour: 1 knot is about 1.151 mph. Treating "20 knots" as "20 mph" understates the real speed by roughly 15 percent, which matters for boats and aircraft.
- Using a rough 1.6 factor for precise work. One mile is 1.609344 km, not 1.6. The shortcut is fine for a quick estimate, but for accurate results use the full factor, which this tool does automatically.
- Mixing up km/h with m/s by a factor of 3.6. 1 m/s equals exactly 3.6 km/h. Forgetting this and treating them as equal makes a speed look 3.6 times slower or faster than it really is.
Glossary
- Metre per second (m/s)
- The SI unit of speed: the distance in metres travelled in one second.
- Kilometre per hour (km/h)
- Distance in kilometres travelled in one hour. The standard road speed unit in most countries.
- Mile per hour (mph)
- Distance in statute miles travelled in one hour. Used for road speeds in the US and UK.
- Knot (kn)
- One nautical mile (1,852 metres) per hour. Standard in maritime and air navigation.
- Foot per second (ft/s)
- Distance in feet travelled in one second. Common in physics and engineering.
Frequently asked questions
How do I convert mph to km/h?
Multiply the speed in mph by 1.609344 to get km/h. For example, 60 mph × 1.609344 ≈ 96.56 km/h. This converter does it instantly for any value.
How many mph is 100 km/h?
100 km/h is about 62.14 mph. To convert km/h to mph, divide by 1.609344, so 100 ÷ 1.609344 ≈ 62.14.
How fast is a knot in mph?
One knot is about 1.151 mph, because a knot is one nautical mile (1,852 m) per hour and a nautical mile is longer than a statute mile. So 20 knots is roughly 23.02 mph.
What is the difference between a knot and mph?
A knot uses the nautical mile (1,852 metres) while mph uses the statute mile (1,609.344 metres). Because a nautical mile is longer, a knot is faster: 1 knot equals about 1.151 mph.
How do I convert m/s to km/h?
Multiply metres per second by 3.6 to get km/h, since there are 3,600 seconds in an hour and 1,000 metres in a kilometre. For example, 10 m/s × 3.6 = 36 km/h.
Are these speed conversions exact?
Yes. The tool converts through metres per second using exact defined factors (1 mph = 0.44704 m/s, 1 knot = 0.514444 m/s, 1 km/h = 0.277778 m/s, 1 ft/s = 0.3048 m/s), so results match official values rather than rough estimates.