Convert Speed
Convert between kilometres per hour, miles per hour, metres per second and knots — for driving, running and navigation.
Runs entirely in your browser — nothing is uploaded
1 km/h equals
0.6213711922mph
1 km/h in every unit
- Metres per second
- 0.2777777778 m/s
- Kilometres per hour
- 1 km/h
- Miles per hour
- 0.6213711922 mph
- Feet per second
- 0.9113444153 ft/s
- Knots
- 0.5399568035 kn
A knot is a nautical mile per hour
Which makes it 1.852 km/h exactly. The name is literal: speed was once measured by paying out a rope with knots tied at intervals and counting how many passed in a fixed time.
Because a nautical mile is a minute of latitude, a ship doing sixty knots would cross a degree of latitude in an hour. That relationship is why the unit survives in shipping and aviation while its cousins did not.
Never say knots per hour
A knot already contains the per hour. Saying knots per hour is like saying miles per hour per hour, which describes acceleration rather than speed.
It is a small thing, but it is one of the reliable ways to tell whether someone knows the subject.
Mach is not in this list, deliberately
Mach 1 is the speed of sound, and the speed of sound is not a fixed number — it depends on the temperature of the air. Around 1,235 km/h at sea level on a mild day, and roughly 1,062 in the thin cold air at cruising altitude.
A converter that offered a single Mach figure would have to pick one of those and stay silent about it. Leaving it out is more honest than answering with a number that is only right sometimes.
Nothing is sent anywhere
Every conversion on this page is arithmetic done in your own browser. No request is made, nothing is stored between visits, and the page keeps working with the connection switched off — which is a reasonable way to check the claim.
Frequently asked questions
What is the quick way to convert km/h to mph?
Multiply by six and drop a digit — roughly. 100 km/h × 6 = 600, so about 60 mph, against a true 62.1. Good enough for reading a foreign speed limit sign at a glance.
What is a four-minute mile in km/h?
About 24.1 km/h, or 6.7 m/s. Running paces are usually given as time per distance rather than distance per time, so convert the pace to a speed first: a mile in four minutes is fifteen miles an hour.
Why does my car show both?
Because a speedometer must be legal in the country the car is sold in, and manufacturers build one instrument for several markets. The smaller scale is normally the one the car was not primarily sold for.
Is anything sent anywhere?
No. The conversion runs in this tab and the page works offline.