What date is 90 days from today? When was 6 weeks ago? Add or subtract any combination of years, months, weeks and days — optionally counting only business days.
How to use the Add or Subtract Days Calculator
- 1 Choose the start date (defaults to today).
- 2 Select add or subtract and enter years, months, weeks and/or days.
- 3 Tick business days to skip Saturdays and Sundays.
Formula
Result = start + years & months (day clamped to month length)
+ weeks × 7 + days (or business days, skipping weekends)
Worked examples
Input: Today + 30 days
Result: Date 30 days ahead
Includes weekends
Input: 31 January + 1 month
Result: 28 February (29 in leap years)
Day clamped to month length
How month arithmetic works
Adding a month keeps the same day number when possible. When the target month is shorter — for example 31 January + 1 month — the result is clamped to the last day of that month (28 or 29 February). This is the same rule spreadsheets and most programming languages use.
Typical uses
- Payment and notice periods ("within 30 days")
- Pregnancy, medication and visa timelines
- Project milestones and sprint planning
Frequently asked questions
What date is 100 days from today?
Leave the start date as today, enter 100 in Days, and the result appears instantly.
How are business days counted?
Monday to Friday count; Saturday and Sunday are skipped. Public holidays are not excluded.
Can I subtract months?
Yes — choose Subtract. Day numbers are clamped in the same way as when adding.
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