Add / Subtract Time Calculator
Add or subtract days, hours, minutes, and seconds from a date and time.
Result date
2026-05-26
Result time
11:30:00
ISO timestamp
2026-05-26T11:30:00+00:00
Offset
2.5 hr
The add/subtract time calculator starts from a local date and time, applies a duration forward or backward, and returns the resulting date, time, and ISO timestamp.
How to Use
The add/subtract time calculator starts from a local date and time, applies a duration forward or backward, and returns the resulting date, time, and ISO timestamp. Fill in Start date, Start time, Operation, Days, Hours, Minutes, and Seconds, then review the calculated Result date, Result time, ISO timestamp, and Offset.
- Open the calculator : Start with Add / Subtract Time Calculator.
- Enter values : Fill in the required inputs and any optional settings.
- Review the result : Read the output and use the about page for more detail if needed.
Common Questions
What does the Add/Subtract Time Calculator estimate?
Add or subtract days, hours, minutes, and seconds from a date and time.
What time settings can change the result?
Date boundaries, local time, daylight-saving changes, and timezone settings can affect the result.