Speed Converter

Convert between km/h, mph, m/s, knots, and feet per second. Shows reference speeds for context.

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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.

How accurate are the Speed Converter’s conversions between km/h, mph, and knots?

The converter uses internationally-defined conversion factors: 1 km/h = 0.621371192 mph, 1 knot = 1.852 km/h (exact), 1 Mach = 343.0 m/s at sea level at 20°C. All results are accurate to at least 9 significant digits. For aviation or navigation use, the knot definition matches the IMO and ICAO standard.

Does the Speed Converter render properly on mobile browsers?

Yes. The tool is built mobile-first with a single-column layout under 640px width, inputs that trigger the numeric keypad on iOS and Android, and unit-swap buttons sized for thumb tapping. The 10+ unit options (km/h, mph, knots, m/s, ft/s, Mach, and more) remain fully accessible without scrolling on phone screens in landscape orientation.

Do I need an account to convert between km/h, mph, knots, m/s, or Mach?

No. The Speed Converter is free with no signup required. All 10+ speed units including km/h, mph, knots, meters per second, feet per second, and Mach number convert instantly in your browser. Nothing is logged or tracked — bookmark the tool and use it as often as needed for driving, aviation, or physics problems.

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).

Created by The Toobits Team · Engineering & Editorial

Toobits is built, tested, and maintained by a small independent engineering team. Every tool is written in TypeScript, runs entirely in the browser, and is reviewed against its source formulas before publication.

Editorial policy · Updated April 2026

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