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Speed Converter
Convert mph, km/h, m/s, knots and ft/s.
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- 1Enter detailsAdd the numbers for your scenario.
- 2CalculateVootkit updates the result instantly.
- 3ReviewCheck totals, notes and breakdowns.
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Always free coreUse the free plan for everyday tasks.
How to use Speed Converter
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02Check totals, notes and breakdowns.
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Learn more about privacyCar dashboards, weather forecasts, marine charts and physics homework all measure the same thing in four different units — and knots, the one used at sea and in the air, is the one most converters leave out.
What Speed Converter does
Converts between m/s, km/h, mph, knots and ft/s using exact factors relative to metres per second.
A knot is one nautical mile per hour — exactly 0.5144444… m/s. Because a nautical mile is a minute of latitude, a vessel at 30 knots covers half a degree of latitude an hour, which is why the unit survives.
Exact factors, in metres per second
| m/s | 1 — the SI unit |
|---|---|
| km/h | 0.2777… — that is 1/3.6 |
| mph | 0.44704 — exact |
| Knot | 0.5144444… — one nautical mile per hour |
| ft/s | 0.3048 — exact |
| Quick check | km/h ÷ 3.6 = m/s |
| Rough check | Knots × 1.15 ≈ mph |
| Default conversion | mph → km/h |
Detailed steps
- Enter the speed.
- Choose the unit you have and the unit you want.
- Read every unit at once.
Worth knowing
Divide km/h by 3.6 to get m/s. It is exact rather than approximate, and it is the conversion that comes up constantly in physics problems where speeds are quoted in km/h and every formula expects m/s. 90 km/h is exactly 25 m/s.
Frequently Asked Questions
What exactly is a knot?
One nautical mile per hour, so about 1.15 mph or 1.85 km/h. It persists because a nautical mile is one minute of latitude, making speed and position arithmetic straightforward on a chart.
How do I convert km/h to m/s in my head?
Divide by 3.6. That is exact — there are 3600 seconds in an hour and 1000 metres in a kilometre, so the factor is 1000/3600.
Is mph exactly defined?
Yes. A mile is exactly 1609.344 m and an hour is 3600 seconds, so one mph is exactly 0.44704 m/s. All the factors here are exact rather than rounded.
Where is ft/s used?
Mostly US engineering and ballistics, where muzzle velocities are conventionally quoted in feet per second. It is otherwise rare in everyday use.
Is Speed Converter free?
Yes. The Vootkit free plan includes 5 tool runs a day. Upgrade to Vootkit Pro for unlimited daily use, an ad-free workspace and saved workflows.
Are my files uploaded?
No. Speed Converter runs entirely in your browser — your file is processed on your own device and never sent to a server. There is nothing for us to store or delete.
Do I need to install anything?
No. Speed Converter works in any modern browser on desktop, tablet or phone. Open the page and start.
How often can I use it? Is there a daily limit?
On the free plan you get 5 tool runs a day. When you reach the limit you'll see a prompt to upgrade, and it resets the next day. Vootkit Pro removes the cap entirely for unlimited daily use.
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