Speed Converter
Convert km/h, mph, m/s, knots, and ft/s with exact factors.
What it does
Road signs, run watches, boats, and wind reports each speak their own speed. The mile based world drives in mph, most countries drive km/h, science uses meters per second, and sea plus air use knots tied to nautical miles.
The tool above converts between all five: km/h, mph, m/s, knots, and ft/s. Enter the value, pick both ends, and read every equivalent below the answer.
The knot has the richest definition. One nautical mile equals one minute of latitude, 1852 meters, so one knot is 1852 meters per hour. Sailors and pilots keep it because charts read in the same minutes.
Running pace inverts the view. Speed asks distance per time while pace asks time per distance, so the pace calculator on this site complements this converter for training plans.
How to use
- Enter the speed number.
- Pick the unit it is written in and the unit you want.
- Read the converted line, then the all units note.
- For speed limits abroad, convert before driving, not after the flash.
Formula
- 1/3.6
- Meters per second in one km/h. An hour holds 3600 seconds.
- 0.44704
- Meters per second in one mph, exact from the mile definition.
- 0.514444
- Meters per second in one knot (1852 m per hour).
Going through m/s keeps one path for all pairs. Highway math also works in reverse: seconds per kilometer equal 3600 divided by km/h.
Worked example
Example: 100 km/h to mph
Value 100, from km/h, to mph.
- To m/s: 100 / 3.6 = 27.7778.
- To mph: 27.7778 / 0.44704 = 62.1371 mph.
- Result: 100 km/h = 62.1371 mph.
- In knots: 27.7778 / 0.514444 = 53.9957 knots.
Reference table
| Speed | km/h | mph | Context |
|---|---|---|---|
| 5:00/km run | 12.0 | 7.5 | Steady amateur run |
| City limit | 50 | 31.1 | Common EU town limit |
| Highway | 100 | 62.1 | Common cruise speed |
| Fast train | 300 | 186.4 | High speed rail |
| Sound at sea level | 1235 | 767 | Mach 1, varies with air |
Limits
- Steady speeds only. Acceleration and gusts need timing, not conversion.
- Wind speeds use the same units but gusts read separately.
- Pace running needs the pace calculator, since min/km inverts speed.
- Sound speed varies with temperature and altitude around the table value.
Common mistakes
- Using 1.6 for the mile and drifting 9 meters per mile.
- Reading knots as mph. A knot runs 15% faster.
- Mixing up per hour and per second by factors of 3600.
- Trusting speedometer optimism. Most cars read 2 to 5% high.
- Converting the limit but forgetting rental units differ.
Try it yourself
Quick checks. Answers sit tucked under each question.
60 mph in km/h?
60 x 1.609344 = 96.56 km/h.
10 m/s in km/h?
10 x 3.6 = 36 km/h.
Questions
How fast is 100 km/h in mph?
62.14 mph. Multiply km/h by 0.621371.
What is a knot in mph?
About 1.15078 mph. Twenty knots is 23 mph.
Why do boats use knots?
Charts measure in nautical miles, so speed in the same unit plots directly.
How do I convert pace to speed?
Divide 60 by pace minutes. A 5:00 pace is 12 km/h.
Are speedometers exact?
No, regulations let them read high by a few percent but never low.
What is Mach 1 in km/h?
Near 1235 km/h at sea level, lower high up where air thins and cools.