Speed Converter
This speed converter switches any velocity between the units you use every day: kilometres per hour (km/h), miles per hour (mph), metres per second (m/s), knots (kn) and feet per second (ft/s). Key in the figure, flag which unit it comes in and which one you want to read it in: the equivalence recalculates itself as you type. It is handy for reading a foreign speed limit, comparing your running pace, working out a wind or boat speed in knots, or converting a velocity for a physics problem into SI units.
Result
=
Publicidad
How it works
Speed is converted using the metre per second as the reference unit, but the case that comes up most is another one: you rent a car in the United States and the speedometer reads miles per hour. A 65 mph sign on an interstate equals 65 × 1.609344 = 104.6 km/h, and the 70 mph of a rural highway are 112.7 km/h; reading them the other way avoids a ticket. The tool first takes your value to m/s by multiplying by the source factor (1 mph = 0.44704 m/s, 1 km/h = 0.277778 m/s) and then divides by the target factor. Because m/s has a factor of 1, it also serves for physics, and the same bridge converts the knots in a weather report: 20 knots of wind are 37 km/h.
Common speeds and limits in km/h, mph and knots
Comparing the same motion across units helps you read foreign speed limits, wind reports or nautical speeds. This table gathers everyday references converted to the three most-used systems:
| Reference | km/h | mph | knots |
|---|---|---|---|
| School zone | 30 | 18.6 | 16.2 |
| City | 50 | 31.1 | 27.0 |
| Urban US/UK (30 mph) | 48.3 | 30 | 26.1 |
| Main road | 90 | 55.9 | 48.6 |
| US highway (55 mph) | 88.5 | 55 | 47.8 |
| Interstate (65 mph) | 104.6 | 65 | 56.5 |
| Rural interstate (70 mph) | 112.7 | 70 | 60.8 |
| Motorway (120 km/h) | 120 | 74.6 | 64.8 |
| Boat / wind (20 knots) | 37.0 | 23.0 | 20 |
| Speedboat (40 knots) | 74.1 | 46.0 | 40 |
| Human sprint (Usain Bolt) | 44.7 | 27.8 | 24.1 |
| Airliner (cruise) | 900 | 559.2 | 486.0 |
Publicidad
Preguntas frecuentes
- How many km/h is 1 mph?
- 1 mile per hour equals about 1.609 km/h. So a 60 mph limit is roughly 97 km/h, and 30 mph is around 48 km/h. The exact factor comes from 1 mile being 1.609344 kilometres.
- How do I convert m/s to km/h?
- Multiply the value in metres per second by 3.6. So 1 m/s = 3.6 km/h and 10 m/s = 36 km/h. To go the other way, divide km/h by 3.6.
- What is a knot?
- A knot is one nautical mile per hour, used in shipping and aviation. One knot equals 1.852 km/h or about 0.514 m/s, so 20 knots is roughly 37 km/h.
- How fast is 100 km/h in mph?
- About 62.14 mph. As a quick mental check, dividing km/h by 1.609 (or multiplying by 0.6214) gives the mph value, so 100 km/h ≈ 62 mph.
- What is ft/s and where is it used?
- Feet per second (ft/s) is common in US physics and ballistics. One ft/s equals 0.3048 m/s or about 1.097 km/h, so 100 ft/s is roughly 30.5 m/s.
- How many km/h is 70 mph?
- 70 mph is 112.7 km/h (70 × 1.609344). It is the usual limit on many US interstates. For a quick mental estimate, multiply mph by 1.6: 70 × 1.6 ≈ 112 km/h.
- Why do planes and ships measure speed in knots?
- A knot is one nautical mile per hour, and the nautical mile equals one minute of arc of latitude on the Earth's surface (1.852 km). That direct link to geographic coordinates makes knots practical for sea and air navigation, which works with charts and latitudes; that is why they survive alongside the metric system.