Speed Converter

Speed limits change units at borders, weather reports quote wind in different scales, and aviation speaks knots. This speed converter translates between kilometers per hour, miles per hour, meters per second, feet per second and knots with exact factors.

The key relationship: 1 mph = 1.609344 km/h exactly, since it inherits the exact mile definition.

Enter valid values to see the results.

Formula

Result = Value × (from-unit in m/s) ÷ (to-unit in m/s)

Base anchors: 1 m/s = 3.6 km/h exactly; 1 mph = 0.44704 m/s; 1 knot = 1.852 km/h (one nautical mile per hour); 1 ft/s = 0.3048 m/s.

What you need

Enter the speed and choose the source and target units.
For driving, km/h and mph are the pair; for running and physics, m/s; for sailing and aviation, knots.
Wind in weather apps is often m/s or knots — convert to km/h or mph for intuition.

Worked example

A 100 km/h highway speed in mph: 100 ÷ 1.609344 = 62.14 mph. A hurricane wind of 40 m/s is 40 × 3.6 = 144 km/h — about 89 mph.

Practical tips

Quick anchor: 100 km/h ≈ 62 mph; 60 mph ≈ 97 km/h. Multiply mph by 1.6 for a fast estimate.
Divide km/h by 3.6 to get m/s — handy for physics problems and braking distances.
A knot is about 1.15 mph — wind speeds in marine forecasts convert almost one-to-one to mph.
Pace (min/km) is the inverse of speed: 12 km/h is a 5:00 min/km running pace.

Speed conversion quick reference

Speed	km/h	mph	m/s
City limit	50	31.1	13.9
Highway	100	62.1	27.8
Fast train	300	186.4	83.3
Airliner cruise	900	559.2	250

Common mistakes

1 Confusing knots with km/h in weather reports — 20 knots is 37 km/h, not 20.
2 Using 1.6 instead of 1.609344 for precision work like speedometer calibration.
3 Forgetting that m/s to km/h is ×3.6, not ×3 — a 20% error.

Frequently asked questions

How do I convert km/h to mph?

Divide by 1.609344 (or multiply by 0.621371). 120 km/h = 74.56 mph.

How do I convert m/s to km/h?

Multiply by 3.6 exactly: 10 m/s = 36 km/h. The factor is exact because 1 hour = 3,600 s and 1 km = 1,000 m.

What is a knot in km/h?

1 knot = 1.852 km/h exactly — one nautical mile (1,852 m) per hour. It is the standard unit in aviation and shipping.

How fast is 60 mph in km/h?

60 × 1.609344 = 96.56 km/h — just under the common 100 km/h highway limit.