What this calculator does
This add time calculator adds durations to each other, such as 1 hour 30 minutes plus 45 minutes, rather than adding a duration onto a starting date and time. That distinction matters: adding time together is a simpler sum of spans, with no calendar or clock involved, just the total length of time across everything entered.
Enter each duration as hours, minutes and, optionally, seconds, separated by commas. The calculator reads each one, converts it to seconds, and adds them all together, then reports the combined total back in the same hours-minutes-seconds form as well as in decimal hours, minutes and seconds on their own.
The formula
Each duration is split into hours, minutes and seconds and converted to a single count of seconds: hours × 3,600 plus minutes × 60 plus seconds. Every duration entered is converted the same way and the seconds are summed, then that total is converted back into hours, minutes and seconds for the combined result.
| Term | Meaning |
|---|---|
| Duration | A length of time, such as 1:30:00 for one hour thirty minutes, not tied to a specific starting point. |
| H:M:S | Hours, minutes, seconds. A duration entered without a seconds figure, such as 2:15, is read as 2 hours 15 minutes. |
| Total duration | The sum of every entered duration, added together as a single combined span of time. |
The inputs explained
| Field | What to enter |
|---|---|
| Durations to add, comma separated (H:M:S or H:M) | List each duration to add, separated by commas, in H:M:S or H:M format. At least two are needed. |
When to use it
Adding time together for a timesheet
Several separate work sessions, each logged as its own duration, need to be added together into a single daily or weekly total before payroll or invoicing.
Working out combined cooking or task time
A recipe or job with several separate timed steps, entered as their own durations, gives a combined total time needed from start to finish.
Adding split times together
A race, workout or journey broken into legs, each timed on its own, needs those separate times added together to get the total elapsed time for the whole thing.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
Adding two durations of different lengths
The first duration is fixed at 45 minutes; the second is varied to show how the total changes.
| Durations entered | Total duration | Total in decimal hours |
|---|---|---|
| 0:45:00, 0:15:00 | 1:00:00 | 1.00 |
| 0:45:00, 1:00:00 | 1:45:00 | 1.75 |
| 0:45:00, 2:30:00 | 3:15:00 | 3.25 |
| 0:45:00, 5:45:00 | 6:30:00 | 6.50 |
Adding three durations together
A single worked example with three durations, matching the calculator’s default values.
| Durations entered | Total duration | Durations added |
|---|---|---|
| 1:30:00, 0:45:00, 2:15 | 4:30:00 | 3 |
Questions
How is this different from adding time to a date?
This calculator adds durations to each other, such as two meeting lengths added together. Adding a duration onto a specific starting date and time, to find what date and time results, is a separate calculation handled by the date and time calculator.
What if I only have minutes, not hours?
Enter 0 for the hours, such as 0:45 for 45 minutes. Leaving the hours off entirely is not supported, since a single number before the first colon is always read as hours.
Can I add more than two durations at once?
Yes. Add as many durations as needed to the comma-separated list; the calculator sums every one entered and reports the combined total, along with a breakdown of each one parsed individually.
What happens if the combined total passes 24 hours?
It is reported honestly as a total duration greater than 24 hours, such as 27:15:00, rather than wrapping back around to a clock time. A duration total is a length of time, not a time of day.
To add a duration onto a specific starting date and time instead, use the date and time calculator. To measure the time between two dates and times rather than adding spans together, see the elapsed time calculator.