How to calculate an average time
An average time is the total time divided by how many times there are. Because minutes and seconds count in sixties, it is easiest to work in seconds:
- Turn each time into seconds. 1:42.35 is 60 + 42.35 = 102.35 seconds.
- Add the seconds together. The five laps in the example make 507.28 seconds.
- Divide by the number of times. 507.28 ÷ 5 = 101.456 seconds.
- Turn the result back into minutes and seconds. 101.456 seconds is 1:41.456.
The average time formula
Average = (t1 + t2 + … + tn) ÷ n, where t1 to tn are the times in seconds and n is how many there are.
The same formula works for any length of time, from sprint splits in hundredths of a second to commutes in hours and minutes.
Averaging times of day
Clock times wrap around at midnight, so an ordinary average gives the wrong answer. The plain average of 11:00 PM and 1:00 AM is noon, but the right answer is midnight.
In times-of-day mode the calculator places each time on a 24-hour clock face and finds the average direction, called a circular mean. That way bedtimes, wake-up times and shift starts that cross midnight average correctly.
Average, median, fastest and slowest
The average uses every time, so one very slow lap pulls it up. The median is the middle time once they are sorted, so it ignores a single bad lap. When the two are far apart, one of your times is unusual.
Fastest and slowest show your spread. A small gap between them means you were consistent.
Questions and answers
How do you average lap times?
Add the lap times together in seconds and divide by the number of laps. Laps of 1:42.35, 1:40.80, 1:41.12, 1:39.96 and 1:43.05 add up to 507.28 seconds. Divided by 5, that is an average lap of 1:41.456.
Which formats can I paste?
One time per line, as seconds (45 or 45.5), minutes and seconds (1:42.35) or hours, minutes and seconds (1:02:30). In times-of-day mode, use clock times such as 23:30 or 11:30 PM. Lines that cannot be read are listed so you can fix them.
Why is the average of 11 PM and 1 AM midnight and not noon?
A plain average treats 11 PM as 23 and 1 AM as 1, and the middle of those numbers is 12, which is noon. On a clock the two times are only two hours apart, with midnight between them. The circular mean measures around the clock, so it finds midnight.
What is the difference between the average and the median?
The average adds every time and divides by the count. The median is the middle time when the times are sorted. With an odd number of times it is the one in the middle, and with an even number it is halfway between the two middle times.
Does it handle milliseconds?
Yes. You can type up to three digits after the seconds, such as 1:39.960. The average is shown with one more decimal place than your most precise time, up to milliseconds.