Speed Converter

Convert km/h, mph, m/s, knots, and more.

Click any result card to use that unit as input.

Kilometers/hour
Miles/hour
Meters/second
Knots
Feet/second
Mach (sea level)
Travel Time Calculator

Enter a speed above first.

Reference Speeds
Walking ~5 km/h ~3 mph
Running ~12 km/h ~7 mph
Cycling ~25 km/h ~15 mph
Car (highway) ~120 km/h ~75 mph
Train (high-sp) ~300 km/h ~186 mph
Sound (sea lvl) ~1,235 km/h ~767 mph
Light ~1,080M km/h ~671M mph

Frequently Asked Questions

How many mph is 100 km/h?

100 km/h = 62.14 mph. To convert km/h to mph: multiply by 0.621371. Quick mental estimate: multiply by 0.6. Highway speed limits of 100 km/h (EU) ≈ 62 mph; 120 km/h ≈ 75 mph.

What is a knot in speed?

A knot = 1 nautical mile per hour = 1.852 km/h = 1.15078 mph. Used in maritime and aviation. A typical commercial aircraft cruises at ~450–560 knots (830–1,040 km/h). A fast sailboat might reach 15–20 knots.

What is Mach 1?

Mach 1 is the speed of sound — approximately 1,235 km/h (767 mph) at sea level and 15°C. The actual speed of sound varies with altitude and temperature (it decreases at higher altitude and colder air). Supersonic aircraft fly above Mach 1; hypersonic is above Mach 5.

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

Multiply m/s by 3.6 to get km/h. Example: a runner at 5 m/s = 5 × 3.6 = 18 km/h. To convert km/h back to m/s: divide by 3.6. This is the most common scientific speed conversion.