BrowserTools

Speed Converter

km/h, mph, m/s, knots, mach

By Guga — BrowserTools maintainer, Tbilisi, Georgia Updated 2026-09-25
Free Private No uploads
What is Speed Converter?

Speed units are all distances divided by an hour or a second, so once the underlying lengths are pinned down the factors become exact. A mile per hour is 0.44704 metres per second because the international mile is 1609.344 m and an hour is 3600 s. A knot is one nautical mile per hour — 1852 m over 3600 s — which makes it 1.15077945 mph, a difference that matters constantly in aviation. Mach is the exception: it is included here at 340.29 m per second, the standard speed of sound at sea level and 15 °C, but air temperature moves that figure, so treat the mach result as a reference rather than a measurement. Six units, live in both directions, with the whole set shown simultaneously below the main fields.

Convert speeds between kilometers per hour, miles per hour, meters per second, feet per second, knots and mach. Live conversion across all units as you type.

Private Speed Converter In Your Browser

Speed Converter is processed locally with client-side JavaScript. Your files never touch a server, and there is no queue to wait in.

Step-by-Step

How to use Speed Converter

1

Fill in the Value box with the speed you have.

2

Set From unit to the scale the figure is quoted in.

3

Set To unit to the scale you need, or use the swap control between them.

4

Compare against the All speed units grid, where tapping a tile switches it to be your target unit.

Key Capabilities
  • Six units covering m/s, km/h, mph, ft/s, knot and Mach
  • Mile per hour and knot derived from the exact statute and nautical mile
  • A labelled note on Mach that flags it as a temperature-dependent approximation
  • All six units displayed at once beneath the converter
Common Use Cases
  • A runner comparing a treadmill readout in km/h with a race distance posted in miles.
  • A sailor translating a weather forecast in knots into the mph that a car forum would quote.
  • A physics student checking a projectile's launch speed against a textbook figure given in metres per second.
Clear Answers

Frequently Asked Questions

How many mph is one knot?
1.15077945, and that is not a rounding artefact. A knot is defined as one nautical mile — 1852 m — per hour, while a mile per hour uses the shorter statute mile of 1609.344 m. Dividing gives the factor exactly, which is why a 100-knot approach is often described as 115 knots of road speed.
How accurate is the Mach figure?
Treat it as a reference. The value used is 340.29 m/s, the standard speed of sound at sea level and 15 °C, which comes to 1225.044 km/h. Real air is rarely at 15 °C — at 0 °C the same figure is closer to 331.3 m/s — so a Mach number computed here is a baseline, not a measurement of your conditions.
Is 100 km/h exactly 62.14 mph?
It is 62.1371192 mph, and 62.14 is simply that value to two decimals. The conversion runs through 0.44704 m/s per mph, which is exact, so 100 km/h divided by 3.6 gives 27.7777… m/s and dividing that by 0.44704 produces the figure you see.
Why is there no miles per second?
Because it rarely appears outside of physics worked examples. The six units here are the ones you meet in daily life — road speed, airspeed and the raw SI figure — and adding a unit you would never use would not make the table more useful.