Add or Subtract Days from a Date
This date calculator adds or subtracts days, weeks, months or years to or from any date, giving you the resulting date instantly.
Last updated 2026-08-14
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quizExample
How this calculator works, with real numbers (no JavaScript needed):
Inputs
- Start date
- 2026-08-14
- Amount
- 30
- Unit
- days
- Add or subtract
- add
Results
- Resulting date
- 13 September 2026
- What was done
- Added 30 days
functionsThe formula
Need to know what date falls 30 days from now, 6 weeks before a deadline, or 3 months after a bill? This calculator takes any date and shifts it forward or backward by days, weeks, months or years.
How it works
- Days / weeks — simple calendar arithmetic: add or subtract the exact number of days (weeks × 7). The result respects month lengths and leap years automatically.
- Months / years — calendar-based: it adds the amount to the month or year, keeping the day of the month. When the target month has fewer days (e.g., adding 1 month to 31 January), the result rolls over to the last valid day (28/29 February, or the 30th).
Worked example
- 14 August 2026 + 30 days = 13 September 2026
- 14 August 2026 − 6 weeks = 3 July 2026
- 31 January 2026 + 1 month = 28 February 2026 (Jan has 31 days, Feb has 28)
- 14 August 2026 + 5 years = 14 August 2031
Common uses
- Contract and notice periods ("45 days from signing")
- Medicine refills and prescriptions
- Billing, EMI and subscription renewal dates
- Warranty and visa validity windows
- Countdown planning for events and trips
If you need the number of days between two known dates instead, use the Days Between Dates calculator.
helpFrequently asked questions
question_markWhat is 30 days from today?
Enter today's date with 30 days added, or use the calculator's default and change the amount. For example, 14 Aug 2026 + 30 days = 13 Sep 2026.
question_markHow do I add months to a date?
Select "Months" as the unit and "Add" as the operation. The calculator keeps the day of the month and rolls over to the last day if the target month is shorter.
question_markWhat happens if I add a month to January 31?
The result rolls over to the last valid day of February (28th, or 29th in a leap year), because February has fewer days than January.