Free Date Add / Subtract
’90 days from today’, ’6 weeks before the deadline’, ’18 months from now’ - date math is easy to get wrong by hand. Enter a start date, choose add or subtract, pick an amount and unit, and instantly get the exact resulting date plus the weekday it falls on.
How to Use the Date Add / Subtract
- Pick the start date.
- Choose Add or Subtract, enter an amount and a unit.
- Click Calculate to see the resulting date and its weekday.
Features
Add or subtract in days, weeks, months or years from any start date, with month arithmetic done the calendar-correct way - adding one month to January 31 lands on the last day of February, not March 3. The result shows the full date and its weekday, so you immediately know whether you have landed on a weekend.
Benefits & Use Cases
Contract managers compute exact end dates from "N days after signing", project planners set milestones like "6 weeks before launch", and HR teams calculate probation or notice end dates. It is also perfect for personal planning: "18 months from now" stops being a guess.
Tips
Use weeks for sprint and project planning since they map cleanly to work cycles. Remember that adding months follows the calendar while adding 30 days is fixed - pick the unit that matches your real requirement. Check the resulting weekday: deadlines landing on Saturdays are easy to miss.
Frequently Asked Questions
What happens when I add one month to January 31?
You land on the last day of February - the 28th, or the 29th in a leap year. The calculator clamps to the end of the shorter month instead of rolling into March.
Can I subtract dates as well as add?
Yes. Choose Subtract from the operation dropdown, enter your amount and unit, and the tool walks the date backwards.
Does it handle leap years?
Yes. February 29 is accounted for automatically, whether you are adding days, months or years across a leap year.
What is the difference between adding a month and adding 30 days?
A calendar month varies from 28 to 31 days, while 30 days is always exactly 30. Use months for calendar-based terms and days for fixed durations.
Can I add years?
Yes - years is one of the four units, alongside days, weeks and months.
Are time zones involved?
No. This is date-only arithmetic, so time zones and daylight saving do not affect the result.
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