Last updated: September 16, 2026
Quick answer: Use the tool above to convert between any speed units. Choose a from-unit and a to-unit, enter a value, and the result updates instantly.
Speed Converter
Convert speed units like km/h, mph, m/s, and knots quickly and accurately.
Speed measures how fast something moves. This converter covers everyday road units (km/h, mph), the scientific unit (m/s), and navigation units (knots, Mach).
How the speed converter works
Each speed unit is stored as its value in meters per second (the base unit), so any unit converts to any other in one step.
Every unit is defined relative to a base unit (m/s), so any unit can convert to any other in one step.
Step-by-step
- Pick the unit you're converting from.
- Pick the unit you're converting to.
- Enter the value.
- Read the result, and adjust precision if needed.
Worked example
Convert 100 km/h to mph:
So 100 km/h is about 62.14 mph.
Speed units reference (relative to the meter per second)
| Unit | Equivalent in m/s |
|---|---|
| Meter per second (m/s) | 1 m/s |
| Kilometer per hour (km/h) | 0.277778 m/s |
| Mile per hour (mph) | 0.44704 m/s |
| Foot per second (ft/s) | 0.3048 m/s |
| Knot (kn) | 0.514444 m/s |
| Mach (at sea level) | 340.29 m/s |
Understanding your result
Results are exact to the precision you select; pick more significant digits for scientific work or fewer for everyday use.
Accuracy & limitations
Uses the international mile (1.609344 km) and nautical mile (1,852 m). Mach depends on air temperature; the value shown assumes sea-level conditions.
Frequently asked questions
How do I convert km/h to mph?
Multiply km/h by 0.621371. For example, 100 km/h is about 62.14 mph.
How fast is one knot?
One knot is one nautical mile per hour, about 1.852 km/h or 1.15 mph.
What is Mach 1?
Mach 1 is the speed of sound, about 340.29 m/s (1,225 km/h) at sea level.
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Author
Shakeel Muzaffar is the Founder and Editor-in-Chief of MultiCalculators.com, bringing over 15 years of experience in digital publishing, product strategy, and online tool development. He leads the platform's editorial vision, ensuring every calculator meets strict standards for accuracy, usability, and real-world value. Shakeel personally oversees content quality, formula verification workflows, and the platform's commitment to publishing tools that are genuinely useful for students, professionals, and everyday users worldwide.
