Speed Converter

Speed converter: a practical guide

A speed converter translates a distance-per-time measurement from one unit into another without changing the underlying motion. A car traveling at 100 kilometers per hour is also traveling at approximately 62.137119 miles per hour. These are two descriptions of the same speed, which helps when reading road signs abroad, checking a forecast, comparing sports performances, or solving a physics problem.

This free Floan speed converter supports kilometers per hour, miles per hour, meters per second, knots, feet per second, centimeters per second, meters per minute and kilometers per second. Enter a value, choose its unit and the unit you need. Results update as you type, and all calculations run in your browser.

How to use the speed converter

Enter the number in the speed field and make sure “From” matches its unit, then pick your target in “To”. The large result shows the converted speed and the formula beneath it shows the calculation. The grid lists the same speed in every unit; select any tile to make it your target. A short note compares the speed with something familiar, and shows running pace in minutes per kilometer and per mile.

Shortcut buttons select common pairs, and the swap control reverses the units. The decimals menu sets how many places are shown. “Copy result” copies the answer with its unit, while “Copy link” copies a URL that reopens this exact conversion, handy for messages and notes. Your last few conversions are kept in this browser only, and you can clear them at any time.

Understanding common speed units

Kilometers per hour and miles per hour

Kilometers per hour (km/h) is the road-speed unit in most metric countries. Miles per hour (mph) serves the same purpose in the United States and the United Kingdom. One international mile is exactly 1.609344 kilometers, so a number in mph is smaller than the matching number in km/h. For example, 80 km/h is approximately 49.709695 mph. If converting km/h to mph makes the number grow, the factor was probably reversed.

Meters per second and feet per second

Meters per second (m/s) is the natural unit in science and engineering because it fits the International System of Units. The BIPM SI Brochure is an authoritative reference for those definitions. One international foot is exactly 0.3048 meters, so 1 ft/s equals exactly 0.3048 m/s. Centimeters per second and meters per minute suit slower movement such as conveyor belts or laboratory motion.

Knots for air and sea travel

A knot is one nautical mile per hour. The international nautical mile is exactly 1,852 meters, so one knot is exactly 1.852 km/h. Knots are used in navigation, aviation and marine weather. Do not treat knots and mph as interchangeable: a nautical mile is longer than a statute mile.

Speed converter formulas and worked examples

The converter uses meters per second as a common reference. It multiplies your input by the source unit’s m/s factor, then divides by the target unit’s factor. This keeps every supported pair consistent, including less familiar combinations.

Convert mph to km/h

Multiply by 1.609344. A speed of 60 mph becomes 96.56064 km/h. Multiplying by 1.6 gives 96, close enough for a rough estimate but not for a report. To go the other way, divide by 1.609344.

Example: 100 km/h to mph

Divide 100 by 1.609344 to get approximately 62.137119 mph, or 62.14 mph rounded. The extra decimals are the arithmetic of the conversion, not a claim that a vehicle holds that speed so precisely. Match your rounding to the reliability of the original reading.

Convert km/h to m/s

A kilometer is 1,000 meters and an hour is 3,600 seconds, so divide km/h by 3.6. For example, 72 km/h is 20 m/s, and 15 m/s is 54 km/h. These factors appear constantly in classroom motion problems.

Convert knots to mph

Multiply by 1.852, then divide by 1.609344. A 20-knot wind is approximately 23.015589 mph, or exactly 37.04 km/h. Keep the full relationship rather than a heavily rounded multiplier. For forecasts and terminology, see the U.S. National Weather Service.

Where speed conversion helps

Travel, driving, and route planning

Abroad, a familiar limit may appear in an unfamiliar unit, so converting beforehand makes signs easier to read. This tool is not a driving aid and should not be used while driving. A conversion also ignores traffic, stopping distance, visibility and road conditions. Journey time depends on average speed: 150 km at an uninterrupted 75 km/h takes two hours, and stops add to that.

Running, cycling, and workout data

Devices may show km/h or mph while training plans use pace in minutes per kilometer or mile. Pace is the reciprocal of speed once units are aligned: 12 km/h is five minutes per kilometer because 60 ÷ 12 = 5. The converter shows pace automatically in its note under the result. A treadmill at 8 mph is approximately 12.874752 km/h, or about 4:40 per kilometer.

Science, engineering, and weather

In physics, converting every quantity to compatible units prevents mistakes; m/s is usually convenient with meters and seconds. Check whether a quoted speed describes linear movement, fluid flow or rotation, since revolutions per minute need extra information. Weather services report wind in knots, mph, m/s or km/h. A gust and a sustained wind are different measurements even when the units match, and measurement height and averaging period also matter.

Accuracy, rounding, and sensible interpretation

The factors rely on the international mile, foot and nautical mile definitions. Results are rounded to the decimals you choose, up to eight, and very small or very large values switch to scientific notation. Display rounding is separate from the underlying factor.

No converter can improve an uncertain input. If a speedometer is accurate to the nearest whole number, six decimals do not make it more accurate. For safety-critical decisions, confirm the result against a professional or official reference.

The tool accepts zero and positive finite numbers. Speed is a magnitude, while signed velocity includes direction. Mach is excluded because it depends on the local speed of sound, which varies with conditions.

Speed converter FAQ

Explore the Floan homepage, learn more about Floan, or contact us to report a conversion issue, including the input value, units and expected result.