Days Calculator
Add or subtract days, weeks, months, or years from any date to find the resulting date.
Adding and subtracting dates — the details
Adding days to a date is straightforward, but months and years introduce edge cases. A month doesn't have a fixed number of days, and leap years mean even years aren't consistent.
- Month overflow: Adding 1 month to 31 January gives 28 February (or 29 in a leap year). The calculator clamps to the last valid day of the target month.
- Leap years: Adding 1 year to 29 February gives 28 February in a non-leap year. The same clamping rule applies.
- Weeks: Adding weeks simply adds multiples of 7 days — no ambiguity.
- Business use: Settlement dates, notice periods, and contract deadlines often require adding a specific number of business days. This calculator counts calendar days — for business day calculations, see the Date Difference Calculator.
🦘 Fun fact: In Australian law, "30 days' notice" typically means 30 calendar days, not business days — but always check the specific legislation or contract. The Acts Interpretation Act 1901 defines how time periods are calculated federally.