Add or Subtract Calendar Days
Move an ISO date forward or backward by a signed whole-day count. Month and year boundaries are handled as calendar dates.
How to use Add or Subtract Calendar Days
- Set “Starting date” using the date picker or your browser’s date format.
- Enter “Days to add (negative to subtract)”, using the units and limits shown in its label.
- Select Calculate or Process. Review the result and any validation message before copying or downloading available output. Reset clears the result and restores the starting inputs.
Method & assumptions
Result = starting UTC calendar date + signed whole-day offset.
Worked example
Adding 2 days to 2024-02-28 gives 2024-03-01.
Results and projections are informational estimates, not financial, medical, legal, tax, or property advice. Check assumptions, units, rounding, and local requirements independently. Investment illustrations do not guarantee returns. Keep original files and check transformed output before use.
Questions, answered
What date range is supported?
Inputs and results must have years 1000–9999. Day offsets must be whole numbers within ±3,000,000.
Where does this calculation run?
It runs locally in your browser. Enter plain numbers without currency symbols or thousands separators; use the same currency and measurement units throughout unless a converter explicitly asks for units.