How the Speed Converter Works
Speed is how far you go in a certain time. Different countries and jobs use different units for it. A car in the United States shows miles per hour, and most other countries use kilometers per hour. Ships and planes use knots, scientists use meters per second, and runners think in minutes per kilometer or per mile. The Speed Converter changes a speed from one unit into another, using the exact size of each unit.
What you enter
- The speed: a number, which can have decimals. For a running pace, you can type minutes, such as 5.5, or minutes and seconds, such as 5:30.
- The unit you have (From), and the unit you want (To). The swap button reverses the two.
How the conversion works
Every unit is defined by its size in meters per second. The converter turns your speed into meters per second, and then into the unit you chose:
meters per second = speed x meters per second in the From unit result = meters per second / meters per second in the To unit
| Unit | Meters per second | Note |
|---|---|---|
| 1 meter per second (m/s) | 1 | The scientific unit |
| 1 kilometer per hour (km/h) | 1 / 3.6 = 0.27778 | 1,000 meters in 3,600 seconds |
| 1 mile per hour (mph) | 0.44704 | Exactly, by definition |
| 1 knot | 1,852 / 3,600 = 0.51444 | One nautical mile per hour, where a nautical mile is exactly 1,852 meters |
| 1 foot per second (ft/s) | 0.3048 | Exactly, by definition |
| Mach 1 | 340.294 | The speed of sound at sea level and 15 °C |
| The speed of light (c) | 299,792,458 | Exactly, by definition |
- Unit: 1 meter per second (m/s)
Meters per second: 1
Note: The scientific unit - Unit: 1 kilometer per hour (km/h)
Meters per second: 1 / 3.6 = 0.27778
Note: 1,000 meters in 3,600 seconds - Unit: 1 mile per hour (mph)
Meters per second: 0.44704
Note: Exactly, by definition - Unit: 1 knot
Meters per second: 1,852 / 3,600 = 0.51444
Note: One nautical mile per hour, where a nautical mile is exactly 1,852 meters - Unit: 1 foot per second (ft/s)
Meters per second: 0.3048
Note: Exactly, by definition - Unit: Mach 1
Meters per second: 340.294
Note: The speed of sound at sea level and 15 °C - Unit: The speed of light (c)
Meters per second: 299,792,458
Note: Exactly, by definition
The results are shown with up to 7 significant digits, so that a very small or very large answer is not rounded to zero.
A worked example
A car travels at 60 miles per hour.
| Unit | Speed |
|---|---|
| Meters per second (60 x 0.44704) | 26.8224 m/s |
| Kilometers per hour (26.8224 x 3.6) | 96.56064 km/h |
| Knots (26.8224 / 0.514444) | 52.13857 knots |
| Feet per second (26.8224 / 0.3048) | 88 ft/s |
| Mach (26.8224 / 340.294) | 0.0788 Mach |
Sixty miles per hour is exactly 88 feet per second. A quick rule: multiply miles per hour by 1.6 to get kilometers per hour, or multiply kilometers per hour by 0.62 to get miles per hour.
Speeds of everyday things
| Thing | km/h | mph | Knots | m/s |
|---|---|---|---|---|
| Walking | 5 | 3.1 | 2.7 | 1.4 |
| Running | 10 | 6.2 | 5.4 | 2.8 |
| Cycling | 20 | 12.4 | 10.8 | 5.6 |
| City speed limit | 50 | 31.1 | 27.0 | 13.9 |
| Highway | 100 | 62.1 | 54.0 | 27.8 |
| Fast highway | 130 | 80.8 | 70.2 | 36.1 |
| High-speed train | 300 | 186.4 | 162.0 | 83.3 |
| Passenger airliner | 900 | 559.2 | 486.0 | 250.0 |
| Speed of sound (Mach 1) | 1,225 | 761.2 | 661.5 | 340.3 |
Chart: how fast is it?
Each block is 7.5 km/h. The bar of the airliner and of sound would be much longer than the chart, so they are shown as a full bar.
Walking █ 5 km/h Running █ 10 km/h Cycling ███ 20 km/h City limit ███████ 50 km/h Highway █████████████ 100 km/h Fast highway █████████████████ 130 km/h Train ████████████████████████████████████████ 300 km/h Airliner ████████████████████████████████████████ 900 km/h (off the scale)
Running pace
Runners often use pace, which is the time for one kilometer or one mile, instead of speed. It is the inverse of speed: a lower pace means a higher speed. The converter changes between the two, and shows a pace as minutes and seconds.
| Pace | Speed in km/h | Speed in mph |
|---|---|---|
| 4:00 per km | 15.00 | 9.32 |
| 5:00 per km | 12.00 | 7.46 |
| 6:00 per km | 10.00 | 6.21 |
| 7:00 per km | 8.57 | 5.33 |
| 8:00 per km | 7.50 | 4.66 |
4:00 /km ████████████████████████████████████████ 15 km/h 5:00 /km ████████████████████████████████ 12 km/h 6:00 /km ███████████████████████████ 10 km/h 7:00 /km ███████████████████████ 8.57 km/h 8:00 /km ████████████████████ 7.5 km/h
A pace of 6:00 per kilometer is the same as 9:39 per mile, because a mile is 1.609 times longer than a kilometer. A pace of 5:30 per kilometer is 10.91 km/h.
Knots
A knot is one nautical mile per hour. A nautical mile is based on the size of the Earth: it is one minute of latitude, and it is exactly 1,852 meters by international agreement. So one knot is 1.852 km/h, or 1.1508 mph. Ships, boats and aircraft use knots, and so does the weather forecast for the sea.
Mach
Mach 1 is the speed of sound. It is not a fixed number, because the speed of sound depends on the temperature of the air. At sea level and 15 °C it is 340.294 m/s, which is 1,225 km/h. At the height where airliners fly, the air is much colder, and Mach 1 is about 1,060 km/h. The converter uses the sea-level value.
Tips
- Check which unit you have. "Miles" and "nautical miles" are different, and so are "knots" and "miles per hour".
- Use the exact factors, not rounded ones. A rounded factor such as 0.2778 for km/h makes every answer a little wrong, and the error grows with the size of the number.
- For a pace, enter minutes and seconds with a colon, for example 5:30. A pace of 5.30 is 5 minutes and 18 seconds.
- Speed limits and speedometers use a single unit. When you drive in another country, check if the signs are in miles or in kilometers.
What this converter does not include
- Mach at other heights and temperatures.
- Speed in other units, such as furlongs per fortnight, or the speed of a rotating object in turns per minute.
- Velocity with a direction. It only gives the size of the speed.
This tool gives a general conversion. For science, navigation or safety, use a certified source.