AnyTool
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How do I convert speed between km/h, mph, m/s and knots?

Type a value into AnyTool Speed Converter and pick the units. It instantly converts both ways between metres per second, kilometres per hour, miles per hour, feet per second, knots, Mach, the speed of light and more, and shows the value in every unit at once in a copyable table. Everything is calculated in your browser, so nothing is uploaded.

  • Live two-way conversion — type in either field and the other updates
  • m/s, km/h, mph, ft/s, knots, km/s, in/s, ft/min, Mach and the speed of light
  • See the value in every unit at once, each row copyable
  • Exact, internationally-defined factors through a metre-per-second base
  • 100% in your browser — no upload, no signup, works offline

What is

Speed Conversion

Speed conversion changes a velocity from one unit to another — for example kilometres per hour to miles per hour. Because speed units are linearly proportional, each one is defined by a single factor relative to a base unit (the metre per second): one km/h is exactly 1/3.6 m/s and one mph is exactly 0.44704 m/s, so converting is multiplying to metres per second and dividing into the target unit.

Converters

Related terms

km/h to mphm/s to km/hKnots to mphMach number

Frequently Asked Questions

Multiply km/h by 0.621371 to get mph. So 100 km/h is about 62.14 mph.

A kilometre per hour is 1/3.6 m/s and a mile per hour is 0.44704 m/s, so 1 km/h equals about 0.621371 mph. To convert km/h to mph, multiply by 0.621371 — for example 100 km/h is about 62.14 mph. To go the other way, multiply mph by 1.609344 to get km/h.

One metre per second is exactly 3.6 km/h, so multiply m/s by 3.6.

Because there are 1000 metres in a kilometre and 3600 seconds in an hour, 1 m/s equals 3600/1000 = 3.6 km/h exactly. So to convert m/s to km/h you multiply by 3.6, and to convert km/h back to m/s you divide by 3.6 (multiply by 0.27778).

A knot is one nautical mile per hour, equal to 1.852 km/h or about 1.15078 mph.

A knot is one nautical mile per hour, used in marine and air navigation. Since a nautical mile is exactly 1852 metres, one knot is 1852/3600 = 0.514444 m/s, which is 1.852 km/h or about 1.15078 mph. AnyTool converts knots alongside km/h, mph, m/s and Mach.

Mach 1 is the speed of sound — about 340.29 m/s (1225 km/h) at sea level, but it varies with temperature.

Mach 1 is the speed of sound, which is not constant: it depends on air temperature and therefore altitude. At sea level near 15 °C it is about 340.29 m/s, roughly 1225 km/h or 761 mph; at high cruising altitude it drops to about 295 m/s. AnyTool uses 340.29 m/s as a practical sea-level reference.

Detailed Explanation

Methodology

How the Speed Converter Works

AnyTool Speed Converter performs every calculation in the browser. Each unit declares a single linear factor relative to a shared metre-per-second base — the exact number of metres per second in one of that unit — so any unit converts to any other through m/s without an N-by-N table. The factors are the internationally-agreed definitions: one km/h is 1/3.6 m/s, one mph 0.44704 m/s, one foot per second 0.3048 m/s, one knot 0.514444 m/s (1852 m / 3600 s) and the speed of light exactly 299,792,458 m/s. A value is multiplied to metres per second and then divided into the target unit.

  • Ten units spanning metric, imperial, marine, aeronautical and physics scales
  • The metre per second is the shared base; each unit is one exact factor
  • Conversion is value to base to value, so any unit maps to any other
  • Editing either field converts both directions live
  • All arithmetic is client-side JavaScript — no server round-trip
How It Works

The Units, Mach and the Speed of Light

The converter covers everyday road speeds (km/h and mph), the SI metre per second used in science, foot per second and foot per minute for engineering and HVAC, inch per second for machinery, the knot used in marine and air navigation, and kilometre per second for orbital speeds. Mach (the speed of sound) is included as a sea-level reference of 340.29 m/s, though it varies with temperature and altitude, and the speed of light c (299,792,458 m/s) is provided as an exact physical constant.

  • Road: kilometre per hour and mile per hour
  • Science / engineering: metre per second, foot per second, inch per second, foot per minute
  • Navigation: knot (one nautical mile per hour)
  • High speed: kilometre per second, Mach (sea-level reference), speed of light c
  • Mach varies with temperature; 340.29 m/s is the standard sea-level value
Privacy & Security

Privacy and Offline Use

Because all conversion runs in the browser, no value is sent to a server, there is no account or tracking, and the page works offline after first load. The converter is built on a shared, unit-tested conversion engine that other AnyTool unit converters reuse, so behaviour is consistent across the site.

Speed conversion: in-browser (AnyTool) vs typical online converters
CapabilityAnyToolTypical online converters
ProcessingRuns in your browserOften server-side
Units10: metric, imperial, marine, aeronautical, physicsOften a smaller fixed set
Two-way inputEdit either field, both updateUsually one-direction with a button
All units at onceYes, copyable tableOften one target at a time
Precision controlAdjustable 0-10 decimalsFrequently fixed
Works offlineYes (PWA)No
Cost / signupFree, no signupOften ad-heavy or gated

AnyTool converts every unit locally through a metre-per-second base and uploads nothing.