Date Calculator
Add or subtract days, weeks, months or years from a date.Date & Time ToolsDate Calculator
Add or subtract days, weeks, months or years from a date. Month-end dates are clamped (Jan 31 + 1 month = Feb 28).
About this tool
Deadline maths with the edge cases handled: month-end clamping and leap years respected, all computed in UTC so daylight saving cannot move the date.
How to use the Date Calculator tool
- Pick the start date. Any calendar date.
- Choose amount, unit and direction. Days, weeks, months or years.
- Read the result. The computed calendar date.
Supported formats
Input
- Plain text or file input
Output
- Converted or analysed output
Inputs are validated before anything is processed. Invalid values and unsupported files are rejected with a clear error instead of failing silently.
Frequently asked questions
Why did Jan 31 plus one month give Feb 28?
Month-end clamping: the result must exist, so it lands on the month last day.
Are leap years handled?
Yes, including the 2024-02-29 plus one year case.
Which timezone is used?
UTC, so daylight-saving shifts cannot move the date.
Privacy
Everything you enter stays in this browser tab. There is no upload endpoint for tool inputs, no account, and no server-side copy of your text or files. Results are produced locally and disappear when you close the page.
No account is required and no file is ever uploaded. See the privacy policy for details about analytics and the limited data this site stores.
Known limitations
- Business-day arithmetic lives in the Business Days tool.
Related tools
Other free tools from the same collection.