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Speed Distance Time Calculator
Solve for speed, distance, or time in mph, km/h, or m/s. The speed formula is distance divided by time, and average speed is total distance over total time.
Enter any two. Leave the one you want blank. Units are converted to match the unit of the answer.
Leave blank to solve for speed. mph, km/h, m/s, or ft/s.
Leave blank to solve for distance. Miles, kilometers, meters, or feet.
Leave blank to solve for time. Hours, minutes, or seconds, or type h:mm or h:mm:ss.
Enter two of speed, distance, and time, and leave the one you want blank.
Enter two of speed, distance, and time, and leave the one you want blank.
This speed calculator solves for whichever of speed, distance, or time you leave blank. 120 miles in 2 hours is 60 mph, 60 mph for 3 hours is 180 miles, and 100 meters in 10 seconds is 10 m/s. Units, including mph, km/h, m/s, and ft/s, are converted to match the unit of the answer. Average speed is total distance divided by total time, so one leg is the average speed for the whole trip. A time of 0 makes speed undefined.
How to calculate speed
The speed formula is speed = distance / time. Speed is distance divided by time. A car that travels 120 miles in 2 hours has a speed of 120 / 2 = 60 mph. A sprinter who covers 100 meters in 10 seconds has a speed of 100 / 10 = 10 m/s. The same relationship is often written v = d/t.
Fill in distance and time, leave speed blank, and the calculator divides for you. Units can be mixed. Units are converted to match the unit of the answer, the speed unit you picked: mph, km/h, m/s, or ft/s. A time of 0 makes speed undefined, because dividing by zero has no result.
How to find distance or time
Rearrange the speed formula to find the other two values. The distance formula in physics, when speed means average speed, is distance = speed × time. At 60 mph for 3 hours, the distance is 60 × 3 = 180 miles.
The time formula is time = distance / speed. At 10 m/s, 100 meters takes 100 / 10 = 10 seconds. The time box also takes h:mm or h:mm:ss, so 1:30 is an hour and a half, and a time answer of a minute or more is also shown in hours, minutes, and seconds. Leave the one you want blank. If you fill in all three, the page says yes or no: whether those numbers agree with speed = distance / time. A negative distance, speed, or time is rejected, because a trip length, a rate, and a duration are zero or greater.
Average speed formula
Average speed is total distance divided by total time. It is not the ordinary average of the speeds along the way. How to find average speed: add the distances, add the times, then divide. A trip of 90 kilometers in 1.5 hours has an average speed of 90 / 1.5 = 60 km/h.
On this calculator one leg is the whole trip, so the speed from that distance and that time is the average speed. For two legs, add first. Suppose the way out is 30 miles in 1 hour (30 mph) and the way back is 30 miles in half an hour (60 mph). Total distance is 60 miles and total time is 1.5 hours, so the average speed is 60 / 1.5 = 40 mph. The mean of 30 mph and 60 mph is 45 mph, and that is not the average speed.
Frequently Asked Questions
What is the formula for speed?
The speed formula is speed = distance / time, which is distance divided by time. In symbols it is often v = d/t. 120 miles in 2 hours is 60 mph, and 100 meters in 10 seconds is 10 m/s. Distance = speed × time, and time = distance / speed.
How do you find average speed?
Average speed is total distance divided by total time. 90 kilometers in 1.5 hours is 60 km/h. Do not average the speeds from each part of the trip unless every part lasted the same amount of time. Add the distances, add the times, then divide.
How do you calculate distance from speed and time?
Use the distance formula, distance = speed × time. This is the physics form of the speed formula when speed means average speed. 60 mph for 3 hours covers 180 miles. Miles, kilometers, meters, and feet are converted to match the distance unit you pick, which is the unit of the answer.
How do you find time from distance and speed?
Time = distance / speed. That is how to find time from the speed formula. Covering 100 meters at 10 m/s takes 10 seconds. If the speed is 0 and the distance is not 0, time is undefined, because that would divide by zero. A time of 0 cannot be used to calculate speed.
How does an mph calculator convert kilometers or meters?
The page converts each entered unit to match the unit of the answer, and the working shows each conversion. An hour is 3600 seconds and a mile is 1609.344 meters, so 120 miles in 2 hours is 60 mph. 100 meters in 10 seconds is 10 m/s, which is not 10 mph. Leave speed blank and set the speed unit to mph when you want miles per hour.