What this tool does
Converts between km/h, mph, m/s, knots, ft/s, and Mach number simultaneously.
Converter and calculator
Speed Converter
Convert between km/h, mph, m/s, knots, and Mach number. Covers everyday driving, aviation, and physics use cases.
Complete guide
How to use Speed Converter
Unit converters guide for speed converter users.
Speed is expressed in km/h in most countries, mph in the US and UK, m/s in physics and science, knots in aviation and maritime, and Mach for supersonic speeds. This converter handles all of them.
Key conversions
1 mph = 1.60934 km/h. 1 knot = 1.852 km/h. 1 m/s = 3.6 km/h. Mach 1 ≈ 340 m/s at sea level.
How to use it
Enter a value in any field. All other units update instantly.
Quick checklist
- Mach 1 depends on altitude and temperature — tool uses 340 m/s (sea level, 15°C).
- Speed limits: US uses mph; most countries use km/h.
- 1 knot = 1 nautical mile per hour = 1.852 km/h.
- Light speed: 299,792,458 m/s = 670,616,629 mph.
Answers
Speed Converter FAQs
How many km/h in 1 mph?
1 mph = 1.60934 km/h.
What is Mach 1 in km/h?
At sea level, 15°C: Mach 1 ≈ 1,225 km/h = 761 mph.
What is a knot?
1 knot = 1 nautical mile per hour = 1.852 km/h = 1.151 mph. Used in aviation and maritime navigation.
How fast is 100 km/h in mph?
100 km/h ÷ 1.60934 = 62.14 mph.