Date Calculator
Add or subtract days, weeks, months and years from any date. See the resulting date, weekday, ISO week and calendar-day shift instantly.
Add or subtract from a date
Combine years, months, weeks and days in one calculation.
How to use the date calculator
Choose a starting date, select whether you want to add or subtract time, and enter any combination of years, months, weeks and days. DateTimeWise applies larger calendar units before smaller ones so month and leap-year boundaries behave like normal calendar math.
Example
If you add 1 month and 10 days to January 25, the calculator first moves one calendar month and then adds ten days. Because months have different lengths, a calendar-month result is not always the same as adding 30 days.
Useful for
Project deadlines, renewal dates, travel planning, notice periods, study schedules, delivery estimates, milestones and any question such as “What date is 90 days from this date?”
Date calculator FAQ
Does the calculator handle leap years?
Yes. Browser calendar arithmetic recognizes leap years and the extra day in February.
Is one month always 30 days?
No. Calendar months retain their real lengths. Use the Days field if you specifically want a fixed number of days.
Can I share a calculation?
Yes. The page keeps the main inputs in the URL so you can copy or share the result.