Speed Converter

Both mph (miles per hour) and km/h (kilometers per hour) measure speed, but use different distance units. One mile equals approximately 1.609 kilometers, so 60 mph is about 96.5 km/h. The US primarily uses mph, while most other countries use km/h.

A knot is one nautical mile per hour. Sailors use knots because nautical miles are based on Earth's latitude lines (1 nautical mile = 1 minute of latitude), making navigation calculations easier. Pilots also use knots as a standard international measurement for air traffic.

Meters per second (m/s) is the SI unit for velocity and is primarily used in physics and scientific calculations. It's the standard measurement in scientific literature and when precise mathematical calculations are needed, as it directly relates to SI base units.

The speed of sound (Mach 1) is approximately 761 mph, 1,235 km/h, or 343 m/s at sea level on a 15°C day. It varies slightly with temperature and altitude. Speeds faster than sound are measured in Mach numbers (Mach 2 is twice the speed of sound).

The fastest crewed speed was achieved during the Apollo 10 mission in 1969, reaching approximately 39,897 km/h (24,791 mph) during re-entry. The fastest unmanned speed is held by the Parker Solar Probe at over 163 km/s (586,800 km/h or 364,600 mph).