Why use Time Calculator
Adding time means adding hours, minutes and seconds separately, then carrying every 60 seconds into a minute and every 60 minutes into an hour. 1:45:30 plus 2:30:45 plus 0:50:15 comes to 5:06:30. This time calculator does that for a whole list at once: type or paste one duration per line and it returns the total as h:mm:ss, in words, as decimal hours, and as total minutes and seconds, along with a running total after every line. Put a minus sign in front of a line to subtract it. It works on lengths of time, such as lap times, track lengths, flight legs or hours worked each day, not on clock times or dates.
Adding and subtracting time: worked examples
Each input is what goes in the Durations box, with a slash standing for a new line.
Three durations with seconds
1:45:30 / 2:30:45 / 0:50:15
Total 5:06:30 (5 hours 6 minutes 30 seconds), Decimal hours 5.11, Total minutes 306.5, Total seconds 18,390, Average of 3 entries 1:42:10
This is the list the page loads with. The running total goes 1:45:30, 4:16:15, 5:06:30.
A week of hours worked
7:30 / 8:15 / 7:45 / 8:00 / 6:30
Total 38:00:00, Decimal hours 38.00, Total minutes 2,280, Average of 5 entries 7:36:00
Track lengths in minutes and seconds
3:42 / 4:05 / 2:58 / 3:31 / 4:47, with two-part times set to Minutes:seconds
Total 0:19:03 (19 minutes 3 seconds), Total seconds 1,143, Average of 5 entries 0:03:48.6
Left on Hours:minutes, the same five lines would be read as 19 hours 3 minutes.
Subtracting two lines from the first
10:00:00 / 2:45:30 / 1:20:45, Operation set to Subtract the other lines from the first
Total 5:53:45, Decimal hours 5.90, Total minutes 353.75. Running total 10:00:00, 7:14:30, 5:53:45
Adding and subtracting in one list
1:15:00 / +0:50:00 / -0:20:00
Total 1:45:00, Decimal hours 1.75, Total minutes 105
Mixed unit entries
1h 30m / 45 min / 2.5 hours / 90s
Total 4:46:30, Decimal hours 4.78, Total seconds 17,190
Lap times with hundredths of a second
1:23.45 / 1:24.10 / 1:22.98, with two-part times set to Minutes:seconds
Total 0:04:10.53, Total seconds 250.53, Average of 3 entries 0:01:23.51
How time addition carries between seconds, minutes and hours
Total seconds = hours × 3,600 + minutes × 60 + seconds, summed over every line; then hours = total ÷ 3,600, minutes = remainder ÷ 60, seconds = what is left
Converting everything to seconds first avoids carrying by hand. For 1:45:30 + 2:30:45 + 0:50:15 the three lines are 6,330, 9,045 and 3,015 seconds, which sum to 18,390. 18,390 ÷ 3,600 is 5 hours with 390 seconds left; 390 ÷ 60 is 6 minutes with 30 seconds left. The total is 5:06:30. Subtraction is the same sum with the subtracted lines counted as negative. Decimal hours are total seconds ÷ 3,600, so 18,390 seconds is 5.11 hours to two places.
Quick sums of common hours and minutes
Results from the calculator for pairs and short lists that come up often.
| Calculation | Result (h:mm:ss) | In words | Decimal hours |
|---|---|---|---|
| 0:45 + 0:30 | 1:15:00 | 1 hour 15 minutes | 1.25 |
| 1:10 + 0:55 + 2:35 | 4:40:00 | 4 hours 40 minutes | 4.67 |
| 2:05 + 1:50 + 3:20 | 7:15:00 | 7 hours 15 minutes | 7.25 |
| 1:15:30 + 0:45:45 | 2:01:15 | 2 hours 1 minute 15 seconds | 2.02 |
| 23:59:59 + 0:00:01 | 24:00:00 | 24 hours | 24.00 |
| 12:30 + 14:45 + 9:50 | 37:05:00 | 37 hours 5 minutes | 37.08 |
| 5:00 − 1:45 | 3:15:00 | 3 hours 15 minutes | 3.25 |
| 8:00 − 1:15 | 6:45:00 | 6 hours 45 minutes | 6.75 |
| 2:15:10 − 0:45:50 | 1:29:20 | 1 hour 29 minutes 20 seconds | 1.49 |
| 0:20 − 1:00 | -0:40:00 | minus 40 minutes | -0.67 |
Two-part entries in this table are hours:minutes.
Duration formats you can type on each line
- Hours, minutes and seconds with colons: 1:45:30. Seconds may have decimals, as in 0:00:59.6.
- Two parts with a colon: 1:45. This is hours:minutes unless you switch the setting to Minutes:seconds, in which case decimals such as 1:23.45 are allowed.
- Units written out or abbreviated: 1h 30m 15s, 1 hr 30 min, 2 hours 15 minutes, 45 sec, 1 day 2 hours. Decimals work too, so 2.5 hours is 2:30:00.
- Values above 59 in the minutes or seconds position: 0:90 is read as 1 hour 30 minutes and carried.
- A leading + or - to set whether that line is added or subtracted. A sign on a line overrides the Operation setting for that line.
- Blank lines are ignored, so you can group entries.
- A bare number such as 90 is rejected because its unit is unknown. Write 90 min or 1:30 instead.
Durations are not clock times
Everything entered here is treated as a length of time. 5:30 means five and a half hours (or five and a half minutes), not half past five, and AM or PM is not accepted. That is why totals run past 24 hours instead of wrapping round to zero.
To find how long it is from one clock time to another, such as 9:00 AM to 5:30 PM, use the hours calculator on this site. To add a list of shifts with breaks and pay, use the timesheet calculator. To change a result such as 7:45 into 7.75 for payroll, the Decimal hours figure here already does that for the total.
The average appears only when every line is added and there are at least two lines. It is the total divided by the number of entries, rounded to the nearest thousandth of a second. A total below zero is shown with a minus sign and a note, since it usually means the lines are in the wrong order. Up to 500 lines are accepted in one go.
Using Time Calculator
- 1
In Durations, enter one length of time per line, for example 1:45:30, 2:30 or 1h 30m 15s.
- 2
To take a line away instead of adding it, start it with a minus sign, as in - 0:20:00. Or set Operation to Subtract the other lines from the first.
- 3
If your entries are minutes and seconds such as 3:45, change A two-part time like 3:45 means to Minutes:seconds. Three-part entries are always hours:minutes:seconds.
- 4
Read Total under Result, along with In words, Decimal hours, Total minutes and Total seconds. When every line is added, an average is shown as well.
- 5
Check the Running total table to see the sum after each line, and copy the Calculation line if you need to show the working.