Speed, Distance & Time Calculator

How to use the speed, distance and time calculator

Speed, distance and time are linked: knowing any two of them fixes the third. Pick the quantity you want from the Calculate options, and the form shows only the fields you need to fill in.

• Speed: enter the distance with its unit, and the duration as hours, minutes and seconds. The result is the average speed over the trip.
• Distance: enter the speed and the duration. The result is how far you travel.
• Time (Duration): enter the distance and the speed. The result is how long the trip takes.

Distances can be in miles, kilometers, yards, feet or meters. Speeds use the matching unit: miles per hour, kilometers per hour, yards per hour, feet per second or meters per second. The distance and speed menus stay paired: choosing a unit in one selects the matching unit in the other (kilometers with km/h, meters with m/s, and so on). The duration boxes accept decimals, so 1.5 hours and 1 hour 30 minutes mean the same. Leave unused boxes empty.

The answer follows the unit you chose for the quantity you supplied. Where it helps, extra units appear in brackets: a distance in feet also shows miles, a distance in meters also shows kilometers, and a speed worked out in yards, feet or meters per hour also lists equivalents such as miles per hour or units per second. For example, 1,500 meters covered in 12 minutes 20 seconds is 7,297.30 m/h, which the result also shows as 2.03 m/s and 7.30 km/h.

All three results are averages. Speed here means total distance divided by total time, including any stops you counted in the duration, so it can be lower than the speed shown on a speedometer at any moment.

The speed formula

Average speed is the distance covered divided by the time taken. In physics the same quantity is called average velocity when direction is taken into account.

speed = distance ÷ timev = d ÷ t

Example. A flight of 1,840 km takes 2 hours 20 minutes. Convert the time to hours first: 2 + 20 ÷ 60 = 2.3333 hours. Then 1,840 ÷ 2.3333 = 788.57 km/h.

If you need a speed in another unit afterwards, multiply or divide by the factors in the conversion section below, or open the speed converter.

The distance formula

Rearrange the speed formula to find how far something travels at a steady average speed.

distance = speed × timed = v × t

Example. A coach keeps to an average of 62 km/h for 3 hours 45 minutes. The time is 3.75 hours, so the distance is 62 × 3.75 = 232.5 km. Entered with a speed in miles per hour, the same calculation returns miles; entered in meters per second with the time in seconds, it returns meters.

The time (duration) formula

Dividing the distance by the speed gives the time the trip takes.

time = distance ÷ speedt = d ÷ v

Example. A driver has 345 km to cover at an average of 92 km/h. The trip takes 345 ÷ 92 = 3.75 hours, which is 3 hours 45 minutes. Speeds counted per hour give an answer in hours, while speeds in feet or meters per second give an answer in seconds, with the hour figure shown alongside.

A common slip is leaving the decimal in a time as if it were minutes. The 0.75 in 3.75 hours is three quarters of an hour, or 45 minutes, not 75 minutes. To split a decimal duration into hours and minutes, multiply the fractional part by 60.

Unit factors and a quick conversion table

The calculator works with consistent units, but you will often need to compare speeds quoted in different ones. These exact factors cover the common cases:

• 1 mile = 1.609344 km = 1,760 yards = 5,280 feet
• 1 m/s = 3.6 km/h ≈ 2.2369 mph
• 1 mph = 1.609344 km/h ≈ 0.44704 m/s ≈ 1.4667 ft/s

For one-off conversions see km/h to mph, mph to km/h and miles to kilometers.

Working with mixed units

The distance and the speed must describe the same kind of length before you divide. Ten kilometers at 6 mph is not 10 ÷ 6: first turn 10 km into 6.2137 miles, then divide by 6 to get 1.036 hours, about 62 minutes. When you use the time mode, the calculator lines the distance unit up with the speed unit for you, so you can enter a distance in one unit and a speed in another.

Times are the other usual source of error. Speeds per hour need the duration in hours, and speeds per second need it in seconds. Mixing a speed in km/h with a duration typed in minutes gives a result that is wrong by a factor of 60.

Finding the average speed of a car trip

1. Measure the distance along the route you took, from an odometer, trip meter, GPS log or a mapping service. A straight line understates road distance.
2. Record the time spent moving. Subtract long stops such as meals if you want the speed while driving, or keep them in if you want the overall trip average.
3. Choose Speed, enter the distance and the duration, and read the result.

For a journey made of several legs at different speeds, add all the distances and all the times first and divide once. Averaging the leg speeds directly only works when the legs take equal time. The average speed calculator handles that case, and the pace calculator converts a running speed to minutes per kilometer or mile.

If speed changes over time and you want to know how quickly, use the acceleration calculator.