Speed Converter
This speed converter changes miles per hour to kilometers per hour and back, plus meters per second, knots and feet per second. Enter one speed and every unit updates live as you type, which makes foreign speed limits, wind reports and physics homework quick to check in a single view.
Speed Converter tool
Converted to every unit
| Unit | Value |
|---|---|
| Miles per hour (mph) | – |
| Kilometers per hour (km/h) | – |
| Meters per second (m/s) | – |
| Knots | – |
| Feet per second (ft/s) | – |
Tap a row value to copy it.
How to use it
- Type the value you want to convert.
- Pick the unit you are converting from.
- Read every other unit at once, and tap a value to copy it.
What is speed conversion?
Speed conversion, or velocity conversion, restates a distance-per-time rate in different units. Because an hour is the same everywhere, converting mph to km/h uses the same factor as miles to kilometers:
km/h = mph × 1.609344A 60 mph limit is 96.6 km/h, and a 100 km/h sign is 62.1 mph. Meters per second links to km/h through a factor of 3.6, so a sprinter at 10 m/s is running 36 km/h. A knot is one nautical mile, exactly 1,852 meters, per hour, which is 1.151 mph. All five units on this page convert through meters per second.
Worked example
US speed limits in km/h
| Road | mph | km/h |
|---|---|---|
| School zone | 25 | 40.2 |
| City street | 35 | 56.3 |
| Two-lane highway | 55 | 88.5 |
| Rural interstate (common) | 70 | 112.7 |
| Fastest posted US limit (Texas SH 130) | 85 | 136.8 |
| Autobahn advisory speed (130 km/h) | 80.8 | 130 |
Miles per hour and kilometers per hour
The two speeds people convert most are miles per hour and kilometers per hour. One mph is exactly 1.609344 km/h, the same factor as miles to kilometers, because the hour cancels out. That is why a 60 mph limit is 96.6 km/h and a 100 km/h sign abroad means 62.1 mph. For a quick estimate, multiply km/h by 0.6 to get mph, or mph by 1.6 to get km/h: 80 km/h is roughly 50 mph, and 30 mph is about 48 km/h.
Meters per second is the scientific unit, and it has an easy relationship with km/h: multiply by 3.6. A sprinter covering 10 m/s is doing 36 km/h, or 22.4 mph. One m/s is also 2.237 mph and 3.281 ft/s. Feet per second still appears in US engineering, ballistics and some sports timing; 1 ft/s is 0.3048 m/s, or 0.682 mph.
Knots, pace and wind
A knot is one nautical mile per hour. The nautical mile is exactly 1,852 meters, so a knot is 1.852 km/h, 1.151 mph or 0.5144 m/s. Aviation, shipping and weather services all report in knots, which is why the 74 mph threshold for a hurricane is the same storm as 64 knots or 119 km/h, and a boat making 20 knots is doing 23 mph. Reading the units side by side makes it easy to sanity-check a figure from a race, a weather report or a wind forecast.
Runners think in pace, which is the inverse of speed. Divide 60 by mph to get minutes per mile: 6 mph is a 10-minute mile, and 7.5 mph is 8 minutes per mile. For kilometers, divide 60 by km/h, so 12 km/h is 5 minutes per kilometer, which works out to 7.46 mph or an 8:03 mile. Convert the speed here, then flip it to pace with that one division.
Common uses
- Reading speed limits abroad
- Converting running and cycling pace
- Physics and homework problems
- Wind and boat speed in knots
- Checking a car's speedometer in the other unit
- Comparing aircraft, train and ship speeds
When to use it
- You are driving abroad and need to convert 100 km/h to mph at a glance.
- A treadmill shows km/h and you think in minutes per mile.
- Physics homework gives meters per second and the answer sheet wants mph.
- A marine forecast lists wind speed in knots and you want mph before heading out.
- You rented a car in Europe and want to know how fast 120 km/h feels in mph before merging (it is 74.6 mph).
Related tools
The Length Converter handles plain distances, miles to kilometers, with no time involved.
The Temperature Converter covers the other half of a foreign weather report.
The Volume Converter helps with gallons and liters when you compare fuel abroad.