Calculate a new date
Order: years → months → days (calendar rules)
Operation
Add or subtract years, months, and days from any start date
Order: years → months → days (calendar rules)
This tool applies years, then months, then days to your start date using the JavaScript date model (same idea as many spreadsheet “EDATE” style flows). Month-end cases (for example January 31 plus one month) follow calendar rollover rules.
Everything runs in your browser; your dates are not uploaded.
That matches common calendar libraries, not “always same day number”.
That matches common calendar libraries, not “always same day number”.