Averaging times fails in the same place adding them does: the minutes are sixtieths, so the arithmetic has to happen in minutes and be converted back at the end. The five entries 7:45, 8:20, 6:55, 9:10, 7:30 average 7h 56m, which is 7.933 decimal hours.
The median is shown next to the mean because they answer different questions. The mean is pulled by extremes; the median is not. For this list the mean is 7h 56m and the median 7h 45m, and where those two separate widely the list is skewed by one unusual entry rather than describing a typical one.
The mean absolute deviation is included as a plain measure of consistency: the average distance of an entry from the mean, in minutes. A small figure means a steady set of times; a large one means the average is hiding a lot of variation.
The sample lists with mean, median and spread table follows the calculator: 4 rows spanning 7:45, 8:20, 6:55, 9:10, 7:30 through 2:30, 5:45, 3:15, 9:00, 4:20, there so the result can be cross-checked against a value you already trust. Nothing has to be entered to see it work: the default for durations to average is 7:45, 8:20, 6:55, 9:10, 7:30, and the output recomputes the moment that changes. The result is also read against 4 bands, from short average at the low end to long average at the high end, each with a note on what that range means in practice. Time Zone Offset Calculator and Total Hours Calculator are the nearest neighbours to this one.
The formula
n- Number of entries
x̄- Mean duration
M- Median duration
MAD- Mean absolute deviation from the mean
How it works, step by step
- Paste the durations separated by commas, each as H:MM.
- Decimal entries such as 7.75 are read as hours.
- Read the mean and compare it with the median.
- Use the deviation figure to judge how consistent the entries are.
Worked examples
Five working days averaged
The entries total 2380 minutes across 5 days, giving a mean of 476.0 minutes — 7h 56m. The median is 7h 45m and the spread runs from 6h 55m to 9h 10m.
When one long entry distorts the mean
The list 6:00, 6:15, 6:30, 6:10, 14:00 has a mean of 7h 47m but a median of 6h 15m. The mean is higher than four of the five entries, which is why the median is shown next to it.
Checking the 8:00, 8:00, 8:00, 8:00, 8:00 row
The reference table lists 8:00, 8:00, 8:00, 8:00, 8:00, giving Mean: 8h 00m, Median: 8h 00m, Spread: 0h 00m. Entering that above should reproduce the same figures — if it does not, the input is being read differently to the way the table assumes.
How to read your score
Frequently asked questions
Should I use the mean or the median?
Use the mean when you need a total divided evenly, such as forecasting capacity. Use the median when you want a typical value and the list contains outliers, since one very long entry cannot drag it.
How is the average calculated exactly?
Every entry is converted to whole minutes, summed, and divided by the count. Only the displayed result is converted back to hours and minutes, so no rounding happens mid-calculation.
What does the deviation figure mean?
It is the mean absolute deviation: the average gap between an entry and the mean, in minutes. Around ten minutes suggests a consistent set; over an hour suggests the average describes very little.
What happens to entries it cannot read?
They are ignored rather than counted as zero, because a zero would drag the mean down and quietly corrupt the result. The entry count in the extras shows how many were actually used.
What do the bands under the mean duration mean?
They label the figure so it can be read without a reference point of your own: Short average from 0 to 4; Part-day average from 4 to 7; Full-day average from 7 to 9; Long average from 9 upwards. The band is a reading aid only — the number itself is exact, and a value sitting just over a boundary is not meaningfully different from one just under it.
What formula does the Average Time Calculator use?
It computes Mean = Σ minutes ÷ n, converted back to hours and minutes, where n is number of entries; x̄ is mean duration; M is median duration; MAD is mean absolute deviation from the mean. The same expression is printed on the page above the inputs, so the result can be reproduced by hand or in a spreadsheet.
Averaging reference
| Entries | Mean | Median | Spread |
|---|---|---|---|
| 7:45, 8:20, 6:55, 9:10, 7:30 | 7h 56m | 7h 45m | 2h 15m |
| 6:00, 6:15, 6:30, 6:10, 14:00 | 7h 47m | 6h 15m | 8h 00m |
| 8:00, 8:00, 8:00, 8:00, 8:00 | 8h 00m | 8h 00m | 0h 00m |
| 2:30, 5:45, 3:15, 9:00, 4:20 | 4h 58m | 4h 20m | 6h 30m |
Medians shown are the middle value of the sorted list, which has an odd length in every row.