Speed Converter

Free online speed converter. Convert between km/h, mph, m/s, knots, and feet per second with reference speeds.

👆Enter a speed value and select your units to convert

How to Use the Speed Converter

Enter a speed value and select your unit. All equivalent values display automatically.

About This Tool

Speed is measured in different units depending on context and country. Road speeds use km/h in most of the world and mph in the US and UK. Mariners and pilots use knots (nautical miles per hour) because they relate directly to degrees of latitude. Scientists and engineers use meters per second (m/s), the SI base unit. This converter handles all five systems and shows every equivalent simultaneously, so you can compare a car's 100 km/h to a ship's 54 knots or a physics problem's 27.8 m/s without switching tools. Pair with the Length Converter for distance units.

Quick Reference Table

km/h	mph
30	18.6
50	31.1
60	37.3
80	49.7
100	62.1
110	68.4
120	74.6
130	80.8

Frequently Asked Questions

How do I convert km/h to mph?

Multiply the km/h value by 0.621371. For example, 100 km/h = 62.14 mph. This converter calculates it instantly.

Is this speed converter accurate?

Yes. It uses standard conversion factors for km/h, mph, m/s, knots, and feet per second.

Does this converter work on mobile?

Yes. Works on all devices with no download required.

Do I need to sign up to use this tool?

No. Completely free with no account needed.

What is a knot and why is it used in aviation?

A knot is one nautical mile per hour (1.852 km/h or 1.151 mph). Nautical miles correspond directly to degrees of latitude, which makes navigation calculations simpler. This is why both marine and aviation industries worldwide use knots as their standard speed unit.

How fast is Mach 1?

Mach 1 is the speed of sound, approximately 1,235 km/h (767 mph) at sea level and 20°C. The exact value depends on air temperature and altitude — at cruising altitude where the air is colder, Mach 1 is approximately 1,062 km/h (660 mph).