Add or Subtract Days Calculator
Count days forward or back from any date.
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Pick a date, choose how many days, and this calculator tells you the exact date that many days before or after it. It handles month lengths and leap years correctly — so '90 days from today' is always right, not off by a day or two.
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What Date Is X Days From Now? — The Quick Answer
Add the days straight to the calendar date. The calculator counts real calendar days — so it correctly skips past different month lengths and adds the extra day in a leap-year February.
Shortcut
resulting date = start date ± number of days
Common day offsets
| You want | Days to add |
|---|---|
| 2 weeks from today | 14 |
| 30 days from today | 30 |
| 90 days from today | 90 |
| 1 year (non-leap) | 365 |
| 6 months (approx.) | ~183 |
Adding days is exact; adding months or years is not the same as adding a fixed number of days, because month lengths vary. If you need 'the same date next month', count forward to that date rather than adding 30 days.
How It Works
The Method
Plain calendar-day arithmetic
Formula
resulting date = start date ± days
Variables
Counting forward
Moves into the future, rolling over month ends correctly — 25 days after 10 January is 4 February.
Counting backward
Moves into the past, e.g. subtracting a contract's notice period to find the last date to give notice.
Note: The count is of calendar days, not business days. To skip weekends (for a delivery estimate or working deadline), use the Business Days Calculator.
Last updated: October 5, 2026
Creators
Computer Scientist & Developer Tools Author
Reviewers
Technical Reviewer
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Your data never leaves your browser. All calculations are 100% private.
Frequently Asked Questions
How do I find the date 30 days from today?
Enter today's date (it's pre-filled), set 30 days, and choose 'Add'. The calculator counts 30 real calendar days and shows you the exact resulting date, handling month-length differences automatically. The same works in reverse with 'Subtract'.
Does it handle leap years?
Yes. The calculation uses true calendar dates, so if your range crosses a 29 February, the extra day is included and the result stays correct. This is exactly where naive 'add 365 days' maths goes wrong.
Is adding 30 days the same as adding one month?
No. Months have different lengths (28–31 days), so 'one month from 15 January' is 15 February, but '30 days from 15 January' is 14 February. For a same-date-next-month deadline, count the calendar, not a fixed day total.
What about weekends and holidays?
This calculator counts every calendar day, including weekends. If you need the date excluding weekends (like a 20-business-day deadline), that's a different calculation — use the Business Days Calculator, which skips Saturdays and Sundays.