Each time against the average

One bar per time, measured from zeroAverage

Each time compared with the average

#	Time	Versus the average
1	4:05	−3.8 s faster
2	4:12	+3.2 s slower
3	3:58	−10.8 s faster
4	4:20	+11.2 s slower
5	4:09	+0.2 s slower

Time formats the average time calculator reads

Two parts mean minutes and seconds; three parts mean hours, minutes and seconds. So 75:30 is 75 minutes 30 seconds, not 75 hours, and an hour-long time needs the h:mm:ss form.

You type	Read as	Seconds
4:05	4 minutes 5 seconds	245
75:30	75 minutes 30 seconds	4,530
1:02:30	1 hour 2 minutes 30 seconds	3,750
1:23.45	1 minute 23.45 seconds	83.45
4:65	Rejected: seconds over 59	none
1:65:00	Rejected: minutes over 59 in h:mm:ss	none

A rejected entry is left out of the average until it is fixed. Fractions of a second take up to three digits, and the average shows tenths, or hundredths when your entries use them.

Both forms mix freely. Three meetings of 1:15:00, 0:50:00 and 1:05:00 total 3:10:00, or 11,400 seconds, and average 1:03:20. A 45:00 entry and a 1:15:00 entry average exactly 1:00:00.

How to calculate an average time by hand

Convert every time to seconds, add them, divide by how many times there are, then turn the answer back into minutes and seconds. The five example laps work out like this:

Lap	Time	Seconds
1	4:05	245
2	4:12	252
3	3:58	238
4	4:20	260
5	4:09	249
Total	20:44	1,244

Multiply the minutes by 60 and add the seconds: 4:05 is 4 × 60 + 5 = 245 seconds.
Add the five values: 1,244 seconds, which is 20 minutes 44 seconds.
Divide by the count: 1,244 ÷ 5 = 248.8 seconds.
Split off whole minutes: 248.8 = 4 × 60 + 8.8, so the average is 4:08.8.

Why minutes and seconds don’t average like decimals

Times count in base 60. 4:50 means 4 minutes 50 seconds, not 4.50 minutes, so averaging the digits as if they were decimals gives a wrong answer. For 4:50 and 5:20, the decimal shortcut gives (4.50 + 5.20) ÷ 2 = 4.85, while the seconds give (290 + 320) ÷ 2 = 305 seconds, which is 5:05.

Times	Decimal digits averaged (wrong)	Seconds averaged (right)
4:30 and 5:00	4.65	4:45
4:50 and 5:20	4.85	5:05
1:40 and 2:30	1.85	2:05
0:45 and 1:30	0.875	1:07.5

A decimal minute converts back by multiplying the fraction by 60: 4.85 minutes is 4 minutes 51 seconds, because 0.85 × 60 = 51.

Average lap time and average pace

Average lap time is the total time divided by the number of laps: a 20:44 run over 5 laps averages 4:08.8 per lap. Pace is the same division with distance in place of laps. A 10-mile run in 1:25:00 is 5,100 seconds, and 5,100 ÷ 10 = 510 seconds, or 8:30 per mile.

Entering each split and reading the Total figure gives the finish time as well. A penalty or a missing segment, such as an extra 0:15, is easier to add with the time addition calculator.

Mean or median: what one slow lap does

The calculator’s result is the mean. The median is the middle time once the list is sorted: 3:58, 4:05, 4:09, 4:12, 4:20 gives 4:09. With an even count, the median is the mean of the two middle times.

The two part ways when one entry is unusual. Replace the 4:09 lap in the example with a 6:30 lap that included a stop:

Laps	Total	Mean	Median
4:05, 4:12, 3:58, 4:20, 4:09	20:44	4:08.8	4:09
4:05, 4:12, 3:58, 4:20, 6:30	23:05	4:37	4:12

That single 6:30 lap raises the mean by 28.2 seconds but the median by only 3 seconds. Remove it to see the average of the regular laps, or keep it when the total effort is what matters. For laps logged as start and end clock times, find each duration between two times first.

Frequently asked questions

How do I average lap times in Excel?

Type each lap as 0:04:05, because Excel reads 4:05 as 4 hours 5 minutes, then use =AVERAGE(A2:A6) and format the cell as mm:ss.0. The five example laps give 04:08.8.

Can I average clock times, such as bedtimes?

Only with care, because the calculator averages durations: 11:30 PM and 12:30 AM entered as 23:30:00 and 0:30:00 average 12:00:00, which is noon. Enter times after midnight with 24 hours added, such as 24:30:00, and the average comes out as 24:00:00, or midnight.