Average speed is total distance divided by total time

To find average speed, divide the total distance traveled by the total time it took to travel that distance. The formula is:

Average Speed = Total Distance ÷ Total Time

This works whether you are measuring a car trip, a running route, or anything else that moves from one place to another. The result tells you how far something travels in each unit of time — miles per hour, kilometers per hour, meters per second, or whatever units match your distance and time measurements.

Key Takeaways

  • Average speed requires two pieces of information: the total distance covered and the total time elapsed, measured in matching units.
  • Divide distance by time using the same units throughout — if distance is in miles, time must be in hours to get miles per hour.
  • Average speed is not the same as the speed shown on a speedometer at any single moment; it smooths out all the stops and starts over the whole trip.
  • Common units for average speed are miles per hour (mph), kilometers per hour (km/h), and meters per second (m/s).

Gather your distance and time measurements

Before you can calculate, you need to know how far something traveled and how long it took. Distance is the total length of the path, not the straight-line distance between start and end. If you drive from home to work and back, the distance is the full round-trip mileage, not zero.

Time is the total elapsed time from start to finish. If you left at 2:00 p.m. and arrived at 3:30 p.m., your time is 1.5 hours, even if you stopped for gas or traffic. Do not subtract rest time unless the question specifically asks for travel time only.

Make sure both measurements use units that make sense together. If your distance is in miles, measure time in hours. If your distance is in meters, measure time in seconds. Mixing units (like miles and seconds) will give you a meaningless result.

Convert time to a single unit if needed

Time often comes in mixed units — hours and minutes, or minutes and seconds. Convert everything to one unit before dividing.

To convert minutes to hours, divide by 60. If a trip took 90 minutes, that is 90 ÷ 60 = 1.5 hours. To convert seconds to minutes, also divide by 60. To convert minutes to seconds, multiply by 60.

Once time is in a single unit, you can divide distance by time. If you traveled 75 miles in 1.5 hours, your average speed is 75 ÷ 1.5 = 50 miles per hour.

Work through a complete example

Suppose you drive 240 kilometers and the trip takes 4 hours. Divide 240 by 4 to get 60 kilometers per hour. That is your average speed.

Now suppose the same 240-kilometer trip takes 3 hours and 45 minutes. First, convert 45 minutes to hours: 45 ÷ 60 = 0.75 hours. Add that to 3 hours to get 3.75 hours total. Then divide: 240 ÷ 3.75 = 64 kilometers per hour.

In a third example, you run 5 miles in 50 minutes. Convert 50 minutes to hours: 50 ÷ 60 = 0.833 hours (or 5/6 hours). Divide 5 by 0.833 to get 6 miles per hour average speed.

Understand what average speed actually measures

Average speed is not the speed you were going at any particular moment. On a highway, you might drive 65 mph for part of the trip, slow to 25 mph in construction, and stop completely at a rest area. Your speedometer shows different numbers throughout, but your average speed smooths all of that into one number.

Average speed also ignores direction. If you drive 100 miles north and then 100 miles south, returning to your starting point, your average speed is still based on the full 200 miles traveled, not the zero-mile displacement. This is different from average velocity, which does account for direction and displacement.

Handle trips with multiple segments

If a journey has several legs — say, driving for 2 hours at varying speeds, then stopping for lunch, then driving for 1 more hour — add up all the distances and all the times, then divide once.

Example: You drive 100 miles in 2 hours, stop for 30 minutes, then drive 60 miles in 1 hour. Total distance is 100 + 60 = 160 miles. Total time is 2 + 0.5 + 1 = 3.5 hours. Average speed is 160 ÷ 3.5 = 45.7 miles per hour. The lunch stop counts as part of the total time because it happened during the trip.

Check your units in the final answer

The units of your answer should always be distance per time. If you divide miles by hours, you get miles per hour. If you divide meters by seconds, you get meters per second. If your answer has different units — like miles per second or hours per mile — you made an error in your calculation or unit conversion.

Write the units clearly with your answer. "50 miles per hour" is complete. "50" by itself is not, because a reader will not know whether it is miles per hour, kilometers per hour, or something else.

Frequently Asked Questions

Is average speed the same as average velocity?

No. Average speed uses total distance traveled. Average velocity uses displacement (the straight-line distance from start to end) and includes direction. If you run around a circular track and return to your starting point, average speed is based on the full lap distance, but average velocity is zero because you ended where you started.

What if I have distance in miles but time in minutes?

Convert time to hours first by dividing minutes by 60. Then divide distance by the converted time. If you travel 30 miles in 45 minutes, convert 45 minutes to 0.75 hours, then divide 30 by 0.75 to get 40 miles per hour.

Do I include stops and delays in the total time?

Yes, unless the question says otherwise. If you stop for gas, traffic, or a meal during the trip, that time counts toward the total. Average speed reflects the real-world pace including all delays.

Can average speed be zero?

Only if the total distance is zero — meaning you did not actually go anywhere. If you traveled any distance at all, average speed will be greater than zero, even if the trip took a very long time.