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Speed limits in mph, wind speed in knots, sprint pace in meters per second, race splits in kilometers per hour — speed units vary a lot by context and country, and converting between them accurately matters for driving, sports, weather, and aviation alike. A rental car's speedometer in a foreign country may only show km/h while you're used to thinking in mph, and a marine weather forecast reporting wind in knots means little unless you can translate it into a familiar unit. This tool converts between five common speed units — meters per second, kilometers per hour, miles per hour, knots, and feet per second — covering everyday driving, sports and athletics, weather, and nautical/aviation contexts in one place.
How it works
Every supported unit is internally defined as a fixed multiple of a single base unit (meters per second). Enter a value, choose the unit you're converting from and the unit you want to convert to; the tool first converts your input into meters per second, then converts that base value into your target unit. Routing every conversion through one shared base means the tool handles any combination of the five supported units with a single consistent method.
- Enter value.
- Enter from.
- Enter to.
- Click Calculate to see your results.
Examples
Converting a speed limit while driving abroad
100 km/h converts to about 62.14 mph — useful when driving in a country using a different unit system than you're used to.
Converting a runner's pace
A sprinter running at 10 meters per second converts to about 36 km/h, or roughly 22.37 mph — a useful reference point for comparing athletic speeds across unit systems.
Converting a marine wind forecast
A forecast calling for 20 knots of wind converts to about 23.02 mph, or roughly 37.04 km/h — helpful for translating a nautical forecast into a more familiar unit.
Who should use it
- Converting driving speed limits between mph and km/h while traveling.
- Converting wind or nautical speeds given in knots.
- Comparing athletic speeds (like sprint or cycling velocity) across different unit systems.
- Converting aviation approach or airspeed figures between knots and mph.
Industry applications
- Travel and transportation
- Aviation and maritime navigation
- Sports and athletics
- Meteorology
Advantages
- Supports common everyday and nautical/aviation speed units.
- Handles any combination of the five supported units through one consistent method.
- Useful across driving, sports, weather, and aviation contexts.
Limitations
- Doesn't include less common units like the Mach number or minutes-per-mile pace.
Common mistakes to avoid
- Confusing knots with mph — they're close but not the same (1 knot ≈ 1.15 mph).
- Assuming km/h and mph differ by a round factor of 2 instead of the actual ~1.609 ratio.
- Mixing up speed (distance per time) with pace (time per distance) when converting running or cycling splits.
Best practices
- Double-check which unit a source (like a weather report or foreign speedometer) is actually using before converting.
- For safety-relevant conversions like driving speed limits, round conservatively rather than up.
- When comparing athletic performances across countries, convert to a single consistent unit (like m/s) before comparing.
Tips
- For quick mental math, 1 km/h is roughly 0.62 mph — useful as a fast sanity check.
- When reading a foreign weather report, check whether wind speed is given in knots or km/h before converting.
- Remember 1 knot is close to 1.15 mph — a handy approximation for nautical and aviation contexts.