Speed Converter

Convert between 7 different speed units from km/h to the speed of light.

Speed Value

From Unit

To Unit

Use Cases

Convert car speed limits between mph and km/h
Convert wind speeds for weather
Calculate aircraft and boat speeds in knots
Compare running and athletic speeds

Frequently Asked Questions

What is the difference between knots and mph?

A knot is one nautical mile per hour (1.15078 mph). Knots are used in aviation and maritime because they relate directly to geographic coordinates.

How fast is Mach 1?

Mach 1 is the speed of sound, approximately 1,235 km/h (767 mph) at sea level. Mach number varies with altitude and temperature.

What is the speed of light in km/h?

The speed of light is approximately 1,079,252,849 km/h (299,792,458 m/s). Nothing can travel faster than the speed of light in a vacuum.

How do I convert mph to km/h in my head?

Multiply mph by 1.6 for a close estimate. For example, 60 mph × 1.6 = 96 km/h (actual: 96.56 km/h). For precise conversions, use this calculator.

What units do different countries use for speed limits?

Most countries use km/h (Europe, Asia, Australia, Canada). The US, UK (mph on major roads), and a few Caribbean nations use mph. Knots are used for maritime speed limits.

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