Quick answer: Speed is distance divided by time. This converter handles kilometers per hour, miles per hour, meters per second and knots: one meter per second is 3.6 km/h, one mph is 1.609 km/h, and one knot is 1.852 km/h. Runners often use pace instead, which is time per unit distance, the inverse of speed.
Last reviewed: September 2026
Key facts
- 100 km/h = 62.14 mph; 1 mph = 1.60934 km/h.
- 1 knot = 1.852 km/h — one nautical mile per hour, the standard at sea and in the air.
- 1 m/s = 3.6 km/h — multiply by 3.6 to go from metres per second to km/h.
- The speed of sound is about 1,235 km/h (Mach 1) at sea level.
Road signs, speedometers and weather reports all speak different speed languages. This free speed converter translates between kilometres per hour, miles per hour, metres per second and knots instantly — essential for driving abroad, sailing and aviation.
Enter a value and pick your units. Every conversion is exact, derived from the definitions of the mile (1,609.344 m) and the nautical mile (1,852 m).
How to use
- Enter a value.
- Choose the from and to units.
- Read the answer and the full table of equivalents below.
How speed conversion works
| Term | Meaning |
|---|---|
| from-unit in km/h | Each unit’s exact definition in km/h. |
| to-unit in km/h | The target unit’s definition in km/h. |
Speed is distance over time, so converting speed is just converting the distance part — the “per hour” follows along.
Worked examples
Driving abroad
100 km/h → mph: 100 ÷ 1.60934 = 62.14 mph.
60 mph → km/h: 60 × 1.60934 = 96.56 km/h — the UK motorway limit in metric.
Wind and running
10 m/s wind → km/h: 10 × 3.6 = 36 km/h.
20 knots → km/h: 20 × 1.852 = 37.04 km/h — a brisk sailing breeze.
Speed units in km/h
| Unit | Equals (km/h) | Think of |
|---|---|---|
| Metre per second (m/s) | 3.6 | Sprint speed × 3.6 |
| Kilometre per hour (km/h) | 1 | City speed limits |
| Mile per hour (mph) | 1.60934 | UK & US speed limits |
| Knot (kt) | 1.852 | Ships and aircraft |
| Foot per second (ft/s) | 1.09728 | Engineering contexts |
Mach 1 (speed of sound) ≈ 1,235 km/h ≈ 767 mph at sea level; it varies with temperature and altitude.
Frequently asked questions
How do I convert mph to km/h?
Multiply by 1.60934: 60 mph ≈ 96.6 km/h. For a quick estimate, multiply by 1.6.
What is a knot?
One nautical mile per hour (1.852 km/h). Ships and aircraft use knots because nautical miles tie directly to latitude: 1 minute of latitude = 1 nautical mile.
How fast is the speed of sound?
About 1,235 km/h (767 mph) at sea level — Mach 1. It drops with altitude as air thins and cools.
Why do the UK and US still use mph?
Both countries retained imperial road signage after metrication stalled; nearly everywhere else posts limits in km/h.
What is 1 m/s in km/h?
Multiply by 3.6: 1 m/s = 3.6 km/h. A 10 m/s wind is 36 km/h.
Sources
Key takeaways
- 100 km/h = 62.14 mph; 1 mph = 1.60934 km/h.
- 1 knot = 1.852 km/h — the sea and air standard.
- 1 m/s = 3.6 km/h: the quickest mental conversion of the set.
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