Add Time Calculator
Add or subtract up to ten durations made of days, hours, minutes and seconds and see the total with every carry done for you. You can also start from a clock time to see what time it will be, and whether that lands on another day.
Last updated November 4, 2026
Shows the time of day after the total is applied.
Result
9 hours 6 minutes 15 seconds
| Measure | Value |
|---|---|
| Days, hours, minutes, seconds | 0d 9h 6m 15s |
| Decimal hours | 9.1 |
| Total minutes | 546 |
| Total seconds | 32,775 |
Show the work
Formula: total seconds = sum of (days × 86,400 + hours × 3,600 + minutes × 60 + seconds), adding or subtracting each row
- Row 1: add 0d 5h 45m 30s = 20,730 seconds.
- Row 2: add 0d 3h 20m 45s = 12,045 seconds.
- Running total in seconds (adds positive, subtracts negative): 32,775.
- Carry: 32,775 seconds = 0d 9h 6m 15s.
Result: 9 hours 6 minutes 15 seconds
How times are added and subtracted
total seconds = Σ ± (days × 86,400 + hours × 3,600 + minutes × 60 + seconds)
Time does not use base 10, so the calculator first converts each duration into seconds: a day is 86,400 seconds, an hour 3,600 and a minute 60. Each row is then added to or subtracted from a running total. Working in whole seconds means there is nothing to carry until the very end.
The final total is converted back into days, hours, minutes and seconds by dividing by 86,400, then 3,600, then 60, keeping each remainder. That is the same carry you do by hand when 75 seconds becomes 1 minute 15 seconds. The total is also shown as decimal hours, total minutes and total seconds.
If the subtractions outweigh the additions, the total is negative. It is shown as the same days, hours, minutes and seconds with a minus sign in front.
See how we calculate for the formulas, sources and review schedule behind every calculator.
Also useful alongside this calculator: Date Calculator, Overtime Calculator and Military Time Converter.
Carrying seconds, minutes and hours
When you add by hand, line the units up and carry from the right. Adding 5 hours 45 minutes 30 seconds to 3 hours 20 minutes 45 seconds gives 75 seconds, which is 1 minute 15 seconds. The minutes become 45 + 20 + 1 = 66, which is 1 hour 6 minutes. The hours become 5 + 3 + 1 = 9. The answer is 9 hours 6 minutes 15 seconds.
The calculator does exactly this, for as many rows as you need. Values do not have to be tidy: 90 minutes or 100 seconds in a row are accepted and carried correctly, so you can paste in figures straight from a stopwatch or a log.
Adding a duration to a clock time
Fill in the optional clock time to apply the total to a time of day. Starting at 10:00 PM and adding 5 hours gives 3:00 AM, one day later. Starting at 9:00 AM and subtracting 10 hours gives 11:00 PM, one day earlier. The result shows the time to the second and says how many days it moved.
The clock is a plain 24-hour wall clock with no dates or time zones attached, so no daylight saving change is applied. To find the gap between two dates and times instead, use the hours calculator.
Subtracting time and negative totals
Choose Subtract on any row to take a duration away. This is useful for removing breaks from a shift, trimming a video edit, or finding how much time is left in a budget of hours. If the result falls below zero, a negative total tells you by how much you went over.
Each row accepts whole numbers of zero or more, and the direction comes from the Add or Subtract choice, not from a minus sign typed into a field.
How to use the Add Time Calculator
- Choose Add or Subtract for the first duration and enter its days, hours, minutes and seconds.
- Use Add another duration for more rows, up to ten, and remove any you do not need.
- Optionally enter a clock time to see the time of day after the total.
- Read the total and its decimal forms, then use Copy, Print or Share.
Worked example
Adding 5 hours 45 minutes 30 seconds to 3 hours 20 minutes 45 seconds gives 20,730 + 12,045 = 32,775 seconds. Dividing by 3,600 gives 9 hours with 375 seconds left, which is 6 minutes 15 seconds. The total is 9 hours 6 minutes 15 seconds, or 9.1 decimal hours.
| Calculation | Total | Clock start | Clock result |
|---|---|---|---|
| 5h 45m 30s + 3h 20m 45s | 9h 6m 15s | - | - |
| 1h 45m + 2h 30m | 4h 15m | - | - |
| 10h 0m − 3h 25m | 6h 35m | - | - |
| 1h 0m − 2h 30m | −1h 30m | - | - |
| Add 5h to a clock | 5h 0m | 10:00 PM | 3:00 AM, 1 day later |
| Subtract 10h from a clock | −10h 0m | 9:00 AM | 11:00 PM, 1 day earlier |
Frequently asked questions
How many durations can I add at once?
Up to ten rows, each with its own days, hours, minutes and seconds, and each set to either add or subtract.
Can I type more than 59 minutes or 59 seconds?
Yes. A row such as 90 minutes or 100 seconds is accepted and carried into hours and minutes in the total, so no pre-tidying is needed.
What does the day offset next to the clock time mean?
It tells you how many whole days the total moved the clock. Later means the result falls on a following day, and earlier means a previous day.
Does it take daylight saving time into account?
No. It is pure clock arithmetic where every day is 24 hours, so a clock change is never added or removed.
Why do the decimal hours not match the minutes I typed?
Decimal hours are the total seconds divided by 3,600 and rounded to two places, so 6 minutes 15 seconds beyond 9 hours shows as 9.1.