Quick answer
Speed units convert through metres per second. 60 miles per hour equals 96.56064 kilometres per hour, since 1 mph is exactly 1.609344 km/h.
Enter a value and choose the units. The calculator returns the converted speed.
Related tools: Playback Speed Calculator: New duration and time saved at a faster playback speed. Cycling Speed Calculator: Average speed from a distance and a time.
How to use the Speed Converter
- Enter value.
- Choose from: Metre per second (m/s), Kilometre per hour (km/h), Mile per hour (mph), Knot (kn), Foot per second (ft/s) and Kilometre per second (km/s) and 2 more.
- Choose to: Metre per second (m/s), Kilometre per hour (km/h), Mile per hour (mph), Knot (kn), Foot per second (ft/s) and Kilometre per second (km/s) and 2 more.
- Enter decimal places (between 0 and 10). It starts at 4.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Value | A number | — |
| From | Choose one: Metre per second (m/s); Kilometre per hour (km/h); Mile per hour (mph); Knot (kn); Foot per second (ft/s); Kilometre per second (km/s); Centimetre per second (cm/s); Speed of light in vacuum (c) | Starts at Metre per second (m/s) |
| To | Choose one: Metre per second (m/s); Kilometre per hour (km/h); Mile per hour (mph); Knot (kn); Foot per second (ft/s); Kilometre per second (km/s); Centimetre per second (cm/s); Speed of light in vacuum (c) | Starts at Kilometre per hour (km/h) |
| Decimal places | A number | ≥ 0, ≤ 10, starts at 4 |
Formula and method
Formula
result = value × (factor of source ÷ factor of target), base unit: metre per second
IEEE-754 double precision; displayed to the chosen number of decimal places (default 4). Very small or large results are shown in scientific notation.
Every unit is defined by an exact or published factor to the base unit (metre per second). The value is multiplied by the source factor and divided by the target factor.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Value = 60; From = Mile per hour (mph); To = Kilometre per hour (km/h); Decimal places = 5.
| Result | Value |
|---|---|
| Mile per hour (mph) → Kilometre per hour (km/h) | 96.56064 |
| Input | 60 Mile per hour (mph) |
Example 2
Inputs: Value = 1; From = Knot (kn); To = Kilometre per hour (km/h); Decimal places = 3.
| Result | Value |
|---|---|
| Knot (kn) → Kilometre per hour (km/h) | 1.852 |
| Input | 1 Knot (kn) |
Example 3
Inputs: Value = 10; From = Metre per second (m/s); To = Kilometre per hour (km/h); Decimal places = 4.
| Result | Value |
|---|---|
| Metre per second (m/s) → Kilometre per hour (km/h) | 36 |
| Input | 10 Metre per second (m/s) |
The first line is the headline result (mile per hour (mph) → Kilometre per hour (km/h)). Below it the speed Converter lists input, which describe the same case from other angles. IEEE-754 double precision; displayed to the chosen number of decimal places (default 4). Very small or large results are shown in scientific notation.
Unit reference
Each unit expressed in the base unit used for the calculation. Conversions go through this base unit, so any unit can be converted to any other in the table.
| Unit | Equals (in metre per second) |
|---|---|
| Metre per second (m/s) | 1 |
| Kilometre per hour (km/h) | 0.2777777778 |
| Mile per hour (mph) | 0.44704 |
| Knot (kn) | 0.5144444444 |
| Foot per second (ft/s) | 0.3048 |
| Kilometre per second (km/s) | 1000 |
| Centimetre per second (cm/s) | 0.01 |
| Speed of light in vacuum (c) | 299792458 |
Handy conversions
1 m/s = 3.6 km/h = 2.237 mph. 1 knot = 1.852 km/h = 1.151 mph. Mach 1 is about 343 m/s at 20 °C (1,235 km/h).
Mental maths
To estimate km/h from mph, multiply by 1.6; 60 mph is about 96 km/h. For km/h to mph, multiply by 0.62.
How the result changes with value
Holding every other input at the first worked example, this table changes only value. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Value | Mile per hour (mph) → Kilometre per hour (km/h) | Input |
|---|---|---|
| 30 | 48.28032 | 30 Mile per hour (mph) |
| 60 | 96.56064 | 60 Mile per hour (mph) |
| 120 | 193.12128 | 120 Mile per hour (mph) |
| 240 | 386.24256 | 240 Mile per hour (mph) |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Value: left empty shows "Enter value." beside that field and no result.
Choosing between the Speed Converter and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Playback Speed Calculator](/technology/playback-speed/) | hours, minutes and playback speed | New duration |
| [Gear Speed Calculator](/engineering/gear-speed-calculator/) | driver gear teeth, driven gear teeth and input speed | Output speed |
| [Cycling Speed Calculator](/fitness/cycling-speed-calculator/) | distance and distance unit | Average speed (km/h) |
| [Speed Distance Time Calculator](/science/speed-distance-time-calculator/) | Distance | |
| [Volume Converter](/converters/volume-converter/) | value, from and to | US gallon → Litre (L) |
Background: unit conversion
Many customary units are defined exactly in terms of metric ones: since the 1959 International Yard and Pound Agreement an inch is exactly 2.54 cm and a pound is exactly 0.45359237 kg (NIST SP 811 lists these). So most length and mass conversions are exact apart from the rounding of the displayed result.
To convert, multiply the value by the source unit's factor to reach the base unit, then divide by the target unit's factor; the unit table on this page lists every factor used. Temperature and fuel economy are the exceptions, because they are not simple multiples.
Assumptions and limitations
- Negative values are allowed
- Zero converts to zero (except L/100 km, where zero is invalid)
- Units from different quantities cannot be converted
- Very large or tiny results switch to exponent notation
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for value to confirm this.
Frequently asked questions
How many mph is 100 km/h?
100 km/h is about 62.14 mph (multiply by 0.6214).
What is a knot?
One nautical mile per hour.
How fast is the speed of sound?
About 343 m/s in air at 20 °C.
What does the Speed Converter calculate?
mph, km/h, knots, m/s and ft/s. It returns Mile per hour (mph) → Kilometre per hour (km/h) and Input.
What formula does the Speed Converter use?
result = value × (factor of source ÷ factor of target), base unit: metre per second. Every unit is defined by an exact or published factor to the base unit (metre per second).
What does the “From” option change?
It sets how the speed is worked out. The choices are Metre per second (m/s), Kilometre per hour (km/h), Mile per hour (mph), Knot (kn), Foot per second (ft/s), Kilometre per second (km/s), Centimetre per second (cm/s) and Speed of light in vacuum (c).
What is an example of a speed result?
With value 60, from Mile per hour (mph), to Kilometre per hour (km/h) and decimal places 5, the mile per hour (mph) → Kilometre per hour (km/h) is 96.56064.
Where does the method come from?
The method follows: NIST SP 811 (2008); 1 knot = 1852 m / 3600 s (international nautical mile); Speed of light in vacuum = 299 792 458 m/s exactly (SI definition, BIPM). Mach is not offered because the speed of sound depends on temperature.
Related calculators
- Playback Speed Calculator — New duration and time saved at a faster playback speed.
- Cycling Speed Calculator — Average speed from a distance and a time.
- Speed Distance Time Calculator — Solve distance, speed or time.
- Volume Converter — Convert litres, gallons, cups, spoons and more.
- Weight Converter — Convert kilograms, pounds, ounces, stone and more.
Sources
- NIST SP 811 (2008)
- 1 knot = 1852 m / 3600 s (international nautical mile)
- Speed of light in vacuum = 299 792 458 m/s exactly (SI definition, BIPM). Mach is not offered because the speed of sound depends on temperature.
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.