Speed Converter

Convert speeds between km/h, mph, meters per second, knots and feet per second. Covers driving, running, sailing, aviation and physics homework in one tool.

How to use this calculator

Enter the speed value.
Choose the from and to units.
Press Convert to see the speed in every unit.

Formula used

1 m/s = 3.6 km/h = 2.23694 mph · 1 knot = 1.852 km/h = 1.15078 mph

A knot is one nautical mile (1,852 m) per hour, used at sea and in aviation. The km/h ↔ m/s factor is exactly 3.6, since an hour has 3,600 seconds and a km has 1,000 meters.

Example calculation

Worked example

Convert 100 km/h to mph: 100 × 0.27778 ÷ 0.44704 = 62.14 mph. The same speed is 27.8 m/s or 54 knots.

Speed units and where they're used

Roads use km/h in most of the world and mph in the US and UK. Science uses m/s (the SI unit). Ships and aircraft use knots, tied to nautical miles which map neatly onto latitude — one minute of latitude is one nautical mile.

Anchors: 100 km/h ≈ 62 mph, 1 m/s = 3.6 km/h, walking pace ≈ 5 km/h, and a 10 km/h running pace is a 6-minute kilometer.

Why use this calculator?

Translate speed limits and forecasts when driving or traveling abroad.
Convert wind speeds between knots, km/h and mph for sailing or weather.
Exact factors for physics — km/h to m/s is a clean ÷3.6.

Frequently asked questions

How do I convert km/h to mph?

Multiply by 0.6214 — so 100 km/h ≈ 62 mph. Going the other way, multiply mph by 1.609. Mental shortcut: mph ≈ km/h × 0.6.

What is a knot?

One nautical mile per hour = 1.852 km/h = 1.151 mph. Ships and planes use knots because nautical miles align with degrees of latitude, simplifying navigation.

How fast is 1 m/s?

3.6 km/h — a slow walk. A sprint is ~10 m/s (36 km/h); highway driving is ~33 m/s (120 km/h).