Time Adder
Add or subtract hours, minutes, and seconds from a clock time and see the result.
Duration
Hours
Minutes
Seconds
Display
Calculated in your browser. Nothing you enter is uploaded.
How to add or subtract time from a clock time
Enter a start time
Set the clock time to calculate from, including seconds if you need that precision.
Choose add or subtract
Pick whether the duration should be added to or taken away from the start time.
Enter the duration
Fill in hours, minutes, and seconds. Any combination works, including more than 60 minutes or seconds.
Read or copy the result
The resulting clock time appears immediately, along with a note if it rolls over into the next or previous day.
Why use this tool
Add or subtract in one tool
A single toggle switches between adding a duration to a start time and subtracting it, without re-entering anything.
Hours, minutes, and seconds together
Enter any mix of hours, minutes, and seconds. Values over 60 are handled automatically, so 90 minutes works the same as 1 hour 30 minutes.
Clear day-rollover notes
When the result crosses midnight, a plain note like "next day" or "2 days later" appears next to the clock time instead of a silently wrong hour.
Normalised duration readout
The duration applied is shown in a reduced form, such as 2h 5m 30s, so it is easy to double-check what was added or subtracted.
12-hour or 24-hour display
Switch the result between 24-hour and 12-hour clock formats to match how you think about the time.
Private by design
Every calculation runs on your device. The times you enter are never uploaded or stored.
About this tool
This tool takes a start time and a duration in hours, minutes, and seconds, and works out the resulting clock time, either by adding the duration or subtracting it. It is built for the everyday question of "what time is it 2 hours 45 minutes from now" or "what time did something start if it finished at 4:15 after running for 90 minutes," without doing the carrying and borrowing by hand.
Because clock time wraps at midnight, adding or subtracting a large enough duration can push the result into the next day or back into the previous one. When that happens, a plain note such as "next day," "2 days later," or "previous day" appears alongside the resulting time, so the answer is never silently off by a day. The duration you entered is also shown in a normalised form, reducing something like 0 hours, 125 minutes, 30 seconds down to 2h 5m 30s, which makes it easy to confirm what was actually applied.
Everything runs in your browser, so the times you enter are never uploaded or stored. To work out a clock time from a starting point using calendar days instead of a duration, use the add or subtract days calculator; to find the span between two clock times or dates, use the date difference calculator; and to see the same duration expressed in more units at once, use the duration calculator.
Frequently asked questions
- How does the time adder calculate the result?
- It converts the start time and the entered duration into seconds, adds or subtracts them depending on the toggle, and converts the total back into a clock time, wrapping around midnight where needed.
- What happens if the result crosses midnight?
- A short note appears next to the result, such as "next day," "2 days later," or "previous day," so it is clear the resulting time belongs to a different calendar day than the start time.
- Can I enter more than 60 minutes or seconds?
- Yes. Values above 60 are handled automatically, so entering 90 minutes gives the same result as entering 1 hour and 30 minutes.
- Does subtracting a large duration wrap around correctly?
- Yes. Subtracting more time than is left before midnight rolls the result back into the previous day, and the day-offset note reflects how many days earlier the result falls.
- Is the time I enter stored anywhere?
- No. The whole calculation happens in your browser, and the times you enter are never uploaded or logged.
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