Free online date calculator
Date Calculator
Add or subtract days, weeks, months, and years from a date and see the result weekday.
Developer utility
Browser based
Runs on the current page
Copy-ready
Use the output where you work
No sign-in
Open the tool and get moving
Date tool
Date Calculator
Add or subtract days, weeks, months, and years from a date using real calendar month lengths.
Result date
Friday, September 4, 2026
ISO date
2026-09-04
Weekday
Friday
Calendar distance
0 years, 1 month, 0 days
Day shift
31 days
Built for developers
Small utilities for fast technical checks.
Entwicklera developer tools are made for everyday formatting, encoding, decoding, generation, and inspection tasks during implementation and debugging.
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Calculate the ISO week number, ISO week-year, weekday number, and weeks in the year.
FAQ
Date Calculator questions.
Can I add months to dates like January 31?
Yes. The calculator respects real month lengths and clamps month-end results to the last valid day of the target month.
Can this subtract dates too?
Yes. Switch the operation from add to subtract and enter the years, months, weeks, or days to remove.
Custom software