sprytools

Speed Converter

Convert speeds instantly between km/h, mph, m/s, knots (kn), Mach (Ma), and the speed of light (c). Live bidirectional conversion, real-world speed references (walking, cars, sound, light), travel time calculator, precision control 0–6 decimals, and copy-to-clipboard. Free, 100% client-side.

4

Reference km/h mph m/s Mach

Click a row to load that speed into the converter.

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Speed Converter — km/h, mph, m/s, Knots, Mach & Speed of Light

Convert between all major speed units instantly — kilometres per hour (km/h), miles per hour (mph), metres per second (m/s), knots (kn), Mach number (Ma), and even the speed of light (c). Fully client-side, no data sent to any server.

How to use the speed converter

Enter a value in any field and all other units update immediately. Use the precision slider (0–6 decimal places) to control output detail. Click Copy All to copy every result to your clipboard as a single line.

Travel Time Calculator

Enter a distance in kilometres and a speed in km/h to compute travel time in hh:mm format. Example: 300 km at 130 km/h = 2 hours 18 minutes.

Conversion Formulas

FromToFormula
km/hmph÷ 1.60934
mphkm/h× 1.60934
km/hm/s÷ 3.6
m/skm/h× 3.6
km/hkn÷ 1.852
knkm/h× 1.852
km/hMach÷ 1235.52
Machkm/h× 1235.52

About the Speed Units

km/h (kilometres per hour) is the standard road speed unit in most countries. Speed limits, vehicle speedometers, and weather data commonly use km/h.

mph (miles per hour) is used in the United States, United Kingdom, and a handful of other countries. The exact conversion factor is 1 mph = 1.60934 km/h (or 1 mile = 1.60934 km exactly since 1959).

m/s (metres per second) is the SI unit for velocity. It is used in physics and engineering. 1 m/s = 3.6 km/h exactly.

Knots (kn) equal one nautical mile per hour. 1 nautical mile = 1.852 km exactly, so 1 kn = 1.852 km/h. Aviation and maritime navigation use knots as the standard.

Mach (Ma) expresses speed relative to the local speed of sound. Mach 1 at sea level and 20 °C ≈ 1235.52 km/h. The value changes with altitude and temperature — aircraft speeds are often quoted in Mach for this reason.

Speed of light (c) is 299,792,458 m/s = 1,079,252,848.8 km/h. It is the universal speed limit; nothing with mass can reach it.

Common Speed References

Objectkm/hmph
Walking53.1
Bicycle2012.4
City car5031.1
Motorway car13080.8
Formula 1350217.5
Speed of sound1,235767
SR-71 Blackbird3,5292,193
Speed of light1,079,252,849670,616,629

FAQ

How do I convert km/h to mph?

Divide km/h by 1.60934. Example: 100 km/h ÷ 1.60934 = 62.14 mph. Or use the tool above — enter any value and all units update instantly.

How do I convert mph to km/h?

Multiply mph by 1.60934. Example: 60 mph × 1.60934 = 96.56 km/h. The tool handles this automatically for all six unit pairs.

What is a knot (kn) and how do I convert it?

1 knot = 1 nautical mile per hour = 1.852 km/h = 1.15078 mph. Knots are the standard speed unit in aviation and maritime navigation. Enter any knot value and the tool converts to all other units instantly.

What is Mach speed?

Mach 1 is the speed of sound — approximately 1235.52 km/h (767.27 mph) at sea level and 20 °C. Mach 2 = 2471.04 km/h. The exact value varies with temperature and altitude. Commercial aircraft cruise at roughly Mach 0.85 (~900 km/h).

How does the travel time calculator work?

Enter a distance in kilometres and a speed in km/h. The tool computes time = distance ÷ speed and displays the result in hh:mm format. Example: 300 km at 130 km/h = 2 hours 18 minutes.

How fast is the speed of light?

The speed of light in vacuum (c) is 299,792,458 m/s = 1,079,252,848.8 km/h ≈ 670,616,629 mph. Nothing with mass can reach or exceed this speed.