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How to use
The speed converter changes values between km/h, mph, m/s, knots and ft/s. It converts through meters per second internally and also shows the most common units together, making quick comparisons easier for driving, sport, physics, navigation and aviation.
- Enter the speed value.
- Choose the source unit and the unit you want to convert to.
- Calculate to see the selected conversion plus km/h, mph, m/s and knots together.
How it is calculated
Example
Example: 100 km/h is about 27.7778 m/s, 62.1371 mph and 53.9957 knots. The conversions use the fixed international mile and nautical mile definitions. Two quick checks: 72 km/h ÷3.6 =20 m/s; 60 mph ×1.609344 =96.56064 km/h. The factor 3.6 comes from 1,000 meters per kilometer and 3,600 seconds per hour; it does not convert miles or knots.
Important notes
A knot is one nautical mile per hour, and the nautical mile is exactly 1,852 meters. mph uses the international mile of exactly 1,609.344 meters. These are unit conversions only; they do not determine legal speed limits, safe driving conditions or certified navigation data.
Worked examples and interpreting results
A speed of 72 km/h equals 20 m/s because a kilometer is 1000 meters and an hour is 3600 seconds. Conversion changes the distance and time units used to describe the speed, not the motion.
| Case | Calculation | Result |
|---|---|---|
| km/h to m/s | 72 × 1000 ÷ 3600 | 20 m/s |
| m/s to km/h | 20 × 3.6 | 72 km/h |
| 72 kilometers per hour to meters per second | 72 ÷ 3.6 | 20 m/s |
| 60 international miles per hour to kilometers per hour | 60 × 1.609344 | 96.56064 km/h |
How to check the result
Divide by 3.6 to convert km/h to m/s; multiply by 3.6 for the reverse. This tool converts units; use average speed to calculate from distance and time. Convert minutes to hours before using distances per hour.
Frequently asked questions
How many mph is 100 km/h?
About 62.1371 mph.
How do I convert m/s to km/h?
Multiply meters per second by 3.6. So 10 m/s equals exactly 36 km/h.
What is the difference between a knot and mph?
A knot is one nautical mile per hour, equal to 1.852 km/h. mph is one international statute mile per hour, equal to 1.609344 km/h.
Why is the km/h–m/s conversion factor 3.6?
A kilometer is 1,000 meters and an hour is 3,600 seconds, so 1 km/h is 1000÷3600 m/s, or 1÷3.6 m/s.
How do I calculate travel time from speed?
With consistent units, time equals distance divided by average speed. For example, 100 km ÷72 km/h is 5,000 seconds, or 1 hour 23 minutes 20 seconds. Use the average speed calculator for distance and time inputs.