How this calculation works
Add or subtract a precise mix of years, months, weeks, and days from a date. The result is calculated locally in your browser from the visible inputs, and the method below remains available for checking.
Worked example
Adding one month to 31 January 2024 clamps to leap-day 29 February 2024.
Assumptions and limits
- Inputs use the units shown beside each field.
- Intermediate values retain precision; displayed values are rounded for readability.
Questions people ask
How does the Date Add / Subtract Calculator work?
It applies this displayed method: Calendar years and months are applied with end-of-month clamping, followed by weeks and days. Values stay in your browser and are not submitted to a server.
What should I check before using the Add or subtract date result?
Inputs use the units shown beside each field. Intermediate values retain precision; displayed values are rounded for readability. Calendar and time-zone results use browser date and IANA timezone data; legal deadlines may follow jurisdiction-specific rules.
Does this Add or subtract date calculator save my information?
No. Calculation inputs are processed on this device. Sharing creates a URL only when you choose the share action.