Add days, weeks, months or years to a date.
Month arithmetic must clamp the day to the target month length, so 31 January plus one month lands on the end of February. Because of that clamping, the order in which months and days are added changes the result. This non-associativity is why contract dates should specify the calculation order rather than just the interval.
Date Addition
Add months first with day clamping, then add the remaining days
Add months first with day clamping, then add the remaining days Month arithmetic must clamp the day to the target month length, so 31 January plus one month lands on the end of February. Because of that clamping, the order in which months and days are added changes the result.
This non-associativity is why contract dates should specify the calculation order rather than just the interval.
This calculator takes 6 inputs: Start date year, Start date month, Start date day, Days to add, Months to add, Years to add. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.