Speed Converter

How do I convert km/h to mph, knots or metres per second?

Use this free online speed converter: enter a number, choose the unit you have and the unit you want, then press the Convert button. It supports metres per second, kilometres per hour, miles per hour, knots and feet per second, and shows the answer on the page with up to six decimal places.

What does the speed converter do and why is it useful?

Speed is quoted in different units depending on where you are and what you are doing. Road signs in most countries use kilometres per hour, while the United States and the United Kingdom use miles per hour. Sailors and pilots talk in knots. Physics classes and weather reports often prefer metres per second, and some engineering and sports data still uses feet per second.

When a car review, a wind forecast, a ship timetable and a science worksheet each use a different unit, comparing them is awkward. This tool puts all five units on one screen. You supply a value, select the units, press the button and read the result. For other everyday measurements, the length unit converter and the temperature converter work in the same way.

How does the converter work under the hood?

All conversions run through one base unit, metres per second. Your value is multiplied by the number of metres per second in the source unit, and that figure is divided by the number of metres per second in the target unit. Using a single base means every unit can be paired with every other without a separate rule for each combination.

The factors come from exact definitions:

• 1 mile per hour = 0.44704 metres per second, exactly.
• 1 knot = 1.852 kilometres per hour, exactly (one nautical mile per hour).
• 1 kilometre per hour = 1 / 3.6 metres per second, because an hour has 3600 seconds and a kilometre has 1000 metres.
• 1 foot per second = 0.3048 metres per second, since a foot is exactly 0.3048 metres.

Results are rounded to at most six decimal places. The tool does not update while you type. The calculation happens only when you press Convert, so the figure on screen always matches the last time you pressed the button.

How do I use the speed converter step by step?

1. Type the speed you want to convert into the value field.
2. Pick the starting unit from the first drop-down list.
3. Pick the target unit from the second drop-down list.
4. Press the Convert button.
5. Read the converted speed on the page. To check another speed or unit pair, change the fields and press Convert again.

What do real conversions look like? Worked examples

Every number below was computed from the exact factors above, so you can reproduce it in the tool.

Example 1: 100 km/h to mph

Input: 100, from kilometres per hour, to miles per hour. Calculation: (100 / 3.6) / 0.44704. Result: 62.137119 mph.

Example 2: 100 km/h to metres per second

Input: 100, from kilometres per hour, to metres per second. Calculation: 100 / 3.6. Result: 27.777778 m/s.

Example 3: 30 knots to km/h

Input: 30, from knots, to kilometres per hour. Calculation: 30 x 1.852. Result: 55.56 km/h. Changing the target to miles per hour gives 34.523383 mph.

Example 4: 60 mph to metres per second and km/h

Input: 60, from miles per hour, to metres per second. Calculation: 60 x 0.44704. Result: 26.8224 m/s. Choosing kilometres per hour instead returns 96.56064 km/h.

Example 5: 10 metres per second to km/h

Input: 10, from metres per second, to kilometres per hour. Calculation: 10 x 3.6. Result: 36 km/h.

Example 6: 88 feet per second to mph

Input: 88, from feet per second, to miles per hour. Calculation: (88 x 0.3048) / 0.44704. Result: 60 mph. This is a handy classic: 88 ft/s equals exactly 60 mph.

How do the units compare at a glance?

Unit	In metres per second
1 m/s	1
1 km/h	0.277778 (1 / 3.6)
1 mph	0.44704
1 knot	0.514444 (1.852 / 3.6)
1 ft/s	0.3048

A quick mental check: a knot is a little faster than a mile per hour, and a mile per hour is about 1.6 times slower than a kilometre per hour. If a result contradicts those rough ideas, recheck the unit selection.

Why do different regions use different speed units?

Metric countries measure road speed in kilometres per hour because their distances are in kilometres. Countries that kept the mile use miles per hour on signs and speedometers. Knots survive in sea and air travel because a nautical mile is tied to the geometry of the globe, which makes navigation sums easier. Metres per second is the unit science prefers, since it fits directly into formulas for force, energy and motion. Feet per second turns up in some engineering, ballistics and sports contexts.

None of these units is more correct than another. They simply describe the same physical quantity with different yardsticks, which is exactly why a reliable converter is handy. When you share a figure with an international audience, state the unit next to the number and consider giving both versions, for example 100 km/h (62 mph).

What tips help me get accurate results?

• Multiply metres per second by 3.6 to reach kilometres per hour. Divide by 3.6 to go back.
• Remember that 1 knot is exactly 1.852 km/h, which is a useful constant for marine and aviation work.
• Convert in one step from the original unit instead of chaining rounded intermediate values.
• Round only the final answer, and pick a precision that fits the situation, such as whole numbers for road speeds.
• If you also need a travel time, convert the speed first and then work out the journey with the date difference calculator or a simple distance divided by speed sum.

What common mistakes should I avoid?

• Swapping the units. Converting 100 from mph to km/h gives a very different answer from 100 from km/h to mph. Check both drop-down lists before pressing Convert.
• Confusing knots with nautical miles. A knot is a speed, one nautical mile per hour. A nautical mile is a distance and is not a unit in this tool.
• Using 3.6 the wrong way round. Multiply to go from m/s to km/h, divide to go from km/h to m/s.
• Treating the result as a measurement. The tool does arithmetic only. A speedometer error or a rounded input will carry through to the answer.
• Expecting live updates. The result changes only when you press the button.

Who uses a speed converter?

Drivers who rent a car abroad compare signs in km/h with a dashboard in mph. Sailors, kayakers and pilots translate knots into land speeds. Runners and cyclists compare pace data from apps that use different units. Students use it for physics problems that demand metres per second, journalists convert wind or vehicle speeds for international readers, and engineers switch between metric and imperial specifications. Anyone reading about a storm, a train or a sprinter eventually needs a conversion.

Is my data private?

Yes. The tool runs 100% in your browser. The numbers you enter are not uploaded, saved or logged, and there is no account or history. Refreshing the page clears everything.

What are the limitations of this tool?

• It supports five units only: metres per second, kilometres per hour, miles per hour, knots and feet per second. Mach numbers, the speed of light and other units are not included.
• Results show up to six decimal places.
• It converts one value at a time, with no batch mode, copy button or downloads.
• It cannot account for conditions such as wind or current. It only converts the number you give it.

Frequently asked questions

How many mph is 100 km/h?

About 62.137119 mph.

How many km/h is one knot?

Exactly 1.852 km/h, since a knot is one nautical mile per hour.

How do I convert m/s to km/h?

Multiply by 3.6. For instance, 10 m/s is 36 km/h.

Is 88 ft/s really 60 mph?

Yes. Using 0.3048 metres per foot and 0.44704 metres per second per mph, 88 ft/s comes out to exactly 60 mph.

Why does the result have so many decimals?

Many conversions between metric and imperial speeds do not end neatly, so the tool shows up to six decimals. Round the figure to suit your purpose.

Can I convert between two imperial units?

Yes. Any of the five units can be converted to any other, including miles per hour to feet per second.

Is a knot faster than a mile per hour?

Slightly. One knot is about 1.150779 mph.

Where can I find other utilities?

See the full list of free tools.

Switch between speed units without the guesswork

Enter the speed, choose two units and press Convert. With exact definitions behind every factor, you can move between km/h, mph, knots, m/s and ft/s and trust the figures you read.