Quickly calculate future or past dates by adding or subtracting days, weeks, months, or years from any starting calendar date.
The Add Days to Date Calculator calculates exact future or past dates by adding or subtracting calendar intervals. When tracking warranty expirations ("valid for 90 days"), lease notice clauses ("give notice 60 days prior"), or health quarantines, calculating dates by hand is susceptible to month-length errors.
This tool supports flexible combinations—such as adding 3 months and 10 days, or subtracting 45 days—with full leap year handling and day-of-the-week identification.
Consumers calculate the exact cutoff date for a 30-day return window or 1-year product warranty.
Tenants determine the exact calendar date required to submit a 60-day notice to vacate prior to lease end.
Patients schedule 6-week or 90-day follow-up appointments accurately.
Pick your base date from the calendar picker.
Select "Add (+)" or "Subtract (-)".
Input number of days, weeks, or months to see the resulting date and day of the week.
Flexible time unit inputs: Days, Weeks, Months, and Years simultaneously
Quick presets for common intervals (+30 days, +60 days, +90 days, +180 days, +1 year)
Displays target day of the week (e.g. Wednesday, Friday) and full written date
100% private in-browser calculation with zero data storage
Find the date 45 days after June 1.
Accounts for 29 remaining days in June plus 16 days in July.
Solution: Use our Business Days Calculator if you need to advance by working days only.
MWT Labs tools are built using modern web primitives—including WebAssembly, Web Workers, and native HTML5 Canvas / Cryptography APIs. When you process images, parse PDF documents, format JSON payloads, or calculate financial schedules, execution happens strictly within your local browser memory sandbox.
Since September only has 30 days, adding 1 month to August 31 results in September 30.