Speed shows up everywhere: motorway signs in km/h, car reviews from the US in mph, physics problems in m/s and weather reports with wind in knots. Converting between them is quick with the right factor. This guide shows how to convert km/h to mph, m/s and knots, with our free Speed Converter.
Key factors
| From | To | Multiply by |
|---|---|---|
| km/h | mph | 0.6214 |
| mph | km/h | 1.609 |
| km/h | m/s | 1 ÷ 3.6 (0.2778) |
| m/s | km/h | 3.6 |
| knots | km/h | 1.852 |
| km/h | knots | 0.540 |
Road speeds
| km/h | mph | m/s |
|---|---|---|
| 30 | 18.6 | 8.3 |
| 60 | 37.3 | 16.7 |
| 80 | 49.7 | 22.2 |
| 100 | 62.1 | 27.8 |
| 120 | 74.6 | 33.3 |
Pakistan’s motorways commonly have a car speed limit of 120 km/h, about 75 mph. Always follow posted signs.
Why 3.6?
1 km = 1,000 m and 1 hour = 3,600 s, so 1 km/h = 1,000 ÷ 3,600 = 0.2778 m/s.
Mental shortcuts
- km/h to mph: multiply by 6 and divide by 10 (100 km/h ≈ 60 mph).
- mph to km/h: multiply by 1.6 (70 mph ≈ 112 km/h).
- km/h to m/s: divide by 3.6, or roughly by 4 and add 10%.
Knots
A knot is one nautical mile per hour, used for ships, aircraft and wind. 1 nautical mile = 1.852 km.
Distance and time
Speed = Distance ÷ Time. To plan a journey of 375 km at 100 km/h average, you need 3.75 hours (3 hours 45 minutes). Convert distances with KM to Miles Converter and estimate fuel with the Petrol Cost Calculator.
For physics and sports uses, read speed units in physics and sports.
Reading a car speedometer
Cars sold in Pakistan show km/h as the main scale; imported cars from the US or UK may show mph in large numbers with km/h in small print. Check which scale is which before driving, especially in a car you have not driven before.
Average vs top speed
A journey’s average speed is usually far below the speed limit because of stops, traffic and turns. For planning, use a realistic average such as 70 to 90 km/h on mixed roads.
Frequently asked questions
How do I convert km/h to mph?
Multiply by 0.6214.
How do I convert km/h to m/s?
Divide by 3.6.
What is 120 km/h in mph?
About 74.6 mph.