Summary: a speed calculator that is free and private
A speed calculator solves the speed, distance and time relationship: speed = distance ÷ time, distance = speed × time and time = distance ÷ speed. Pick what you want to find, enter the other two values in the units you have, and the answer appears in every unit of its kind (km/h, mph, m/s, knots and ft/s for a speed; kilometres, metres, miles, feet and nautical miles for a distance; hours, minutes and seconds for a time), together with a running pace per kilometre and per mile. It runs in your browser, nothing is uploaded (you can check the Network tab in DevTools), and it needs no account.
The result is an average: total distance over total time. If you are comparing units rather than solving a journey, the unit converter covers speed and many other quantities.
Speed unit conversions
| 1 unit equals | km/h | mph | m/s |
|---|---|---|---|
| 1 km/h | 1 | 0.621371 | 0.277778 |
| 1 mph | 1.609344 | 1 | 0.44704 |
| 1 m/s | 3.6 | 2.23694 | 1 |
| 1 knot | 1.852 | 1.15078 | 0.514444 |
| 1 ft/s | 1.09728 | 0.681818 | 0.3048 |
Keep the units consistent when you calculate by hand: km/h goes with kilometres and hours. The calculator avoids that trap by converting everything to metres and seconds internally. For distances alone, see the length converter.
Table of Use: speed, distance and time examples
| Situation | Find | You enter | Result |
|---|---|---|---|
| Drive across a region | Speed | 100 km in 2 hours | 50 km/h (31.0686 mph) |
| Marathon finish | Speed and pace | 42.195 km in 4 hours | 10.5488 km/h; 5:41 per km, 9:09 per mile |
| 5K run | Speed and pace | 5 km in 25 minutes | 12 km/h; 5:00 per km, 8:03 per mile |
| Track lap | Speed | 400 m in 60 seconds | 24 km/h (6.66667 m/s) |
| Highway driving | Distance | 60 mph for 3 hours | 180 miles (289.682 km) |
| Sailing passage | Distance | 12 knots for 10 hours | 120 nautical miles (222.24 km) |
| Coach journey | Time | 150 km at 75 km/h | 2h 00m 00s |
| Long drive | Time | 300 miles at 55 mph | 5h 27m 16s |
Planning a longer trip? Pair the time with the fuel cost calculator for the bill, or the time zone converter to find your arrival time in local terms.
Features
- Three modes under What to Calculate: Speed, Distance or Time. The fields you do not need are hidden.
- Speed units km/h, mph, m/s, knots and ft/s; distance units kilometres, metres, miles, feet and nautical miles.
- Time entered as hours, minutes and seconds, added together. Decimals work with a point or a comma, so 1.5 hours equals 1 hour 30 minutes.
- The answer is repeated in every other unit under In Other Units. A Time answer is also spelled out, for example 2 hours, 0 minutes, 0 seconds, and listed in hours, minutes and seconds.
- A Pace panel with minutes per kilometre and per mile, shown for speeds from 0.1 km/h up to 3,600 km/h.
- Results show up to six significant digits, and from 100,000 upward are rounded to whole numbers.
- A copy button puts the main result on the clipboard. Exact factors are used: 1 mile is 1,609.344 m, 1 foot is 0.3048 m and 1 knot is 1,852 m per hour.
How to Use the Speed Calculator
- Under What to Calculate?, press Speed, Distance or Time.
- Enter the Speed or Distance you know and pick its unit in the list beside the box.
- For Speed and Distance, fill in the Time boxes: hours, minutes and seconds. Leave unused boxes empty.
- Read the large answer, the In Other Units list and the Pace panel. The result needs values above zero.
- Press the copy icon (Copy result) to take the answer with you.
To time a real run or ride, start the online stopwatch and type the total into the Time boxes. For a multi-day trip, the date difference calculator counts the days between two dates.
Who Can Use It
- Runners and cyclists turning a finishing time into pace per kilometre or per mile. The calorie calculator helps plan daily energy needs for training.
- Drivers and travellers estimating journey time or how far they will get by a set hour.
- Sailors and pilots working in knots and nautical miles.
- Students checking speed, distance and time homework, with the formula shown beside the result. The scientific calculator covers the rest of the sums.
FAQs
How do I calculate speed from distance and time?
Divide the distance by the time: speed = distance ÷ time. A car that covers 100 km in 2 hours averages 50 km/h, which is about 31.07 mph. In the calculator, choose Speed under What to Calculate, enter the distance with its unit and the time in hours, minutes and seconds, and the speed appears in five units at once.
How do I convert km/h to mph?
Multiply km/h by 0.621371 to get mph, or multiply mph by 1.609344 to get km/h. So 100 km/h is 62.14 mph and 60 mph is 96.56 km/h. The conversion is exact because the international mile is defined as 1,609.344 metres, and the calculator shows km/h, mph, m/s, knots and ft/s side by side.
How do I work out running pace per kilometre or per mile?
Pace is time divided by distance, the inverse of speed. A marathon of 42.195 km in 4 hours is 10.5488 km/h, which is a pace of 5:41 per kilometre or 9:09 per mile. Enter the distance and your finishing time, and the Pace panel shows both, rounded to the nearest second.
How do I find out how long a journey will take?
Divide the distance by your expected average speed: time = distance ÷ speed. Driving 150 km at 75 km/h takes 2 hours, and 300 miles at 55 mph takes 5 hours 27 minutes. Choose Time under What to Calculate. The answer assumes a constant speed, so add the stops, traffic and fuel breaks you expect separately.
What is a knot, and how does it compare with mph?
A knot is one nautical mile per hour, and a nautical mile is exactly 1,852 metres. That makes 1 knot 1.852 km/h, about 1.151 mph or 0.514 m/s. Ships and aircraft report speed in knots. Choose knots in the speed unit list, or Nautical Miles for distance, and the calculator converts the rest.
Is this average speed or instantaneous speed?
It is average speed: total distance divided by total time. It cannot see stops, hills or changes of pace on the way, so a trip with breaks has a lower average than the speed shown on the dashboard while driving. For a stop-start trip, enter the moving time to get your moving average instead.
Why does the speed calculator say my number could mean two things?
A figure such as 40,075 can be read as 40.075 or as forty thousand and seventy-five, depending on the country. The speed and distance boxes will not guess, so they ask you to retype it with a point (40.075) or without a comma (40075). Plain forms such as 1,5, which can only be 1.5, and 1,000,000 are read directly.