Speed Converter

Convert between km/h, mph, m/s, knots and Mach.

What is a Speed Converter?

A speed converter translates speed values between units used in different contexts: km/h (road speeds in most countries), mph (road speeds in the US and UK), m/s (scientific and physics calculations), knots (maritime and aviation), and Mach (supersonic speeds).

How to Use This Tool

  1. Enter a speed value in any unit field.
  2. All other units update in real time.

Common Speed References

Walking: ~5 km/h = ~3 mph. City speed limit: 50 km/h = 31 mph. Highway: 120 km/h = 75 mph. Speed of sound (Mach 1): 1,235 km/h = 767 mph at sea level. Speed of light: 1,079,252,848 km/h.

What is a Knot?

A knot is one nautical mile per hour (1.852 km/h). It is the standard unit for maritime and aviation speeds worldwide. The name comes from the old method of measuring ship speed using a knotted rope thrown overboard.

Frequently Asked Questions

How fast is Mach 1?

Mach 1 (the speed of sound) is approximately 1,235 km/h (767 mph) at sea level at 20°C. It varies with temperature and altitude.

What is the difference between km/h and kph?

They are the same. "km/h" and "kph" (kilometers per hour) are interchangeable abbreviations.

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**Disclaimer:** All conversions happen in your browser. Files and data are not uploaded to any server. Conversion results are calculated using standard formulas — verify critical calculations with authoritative sources.