Add Months to Date
What date is N months from now?
Months added on the calendar, with the end-of-month case handled explicitly — 31 January plus one month is 28 February, and the page says so rather than silently landing in March.
How this is worked out
- Clamping to the shorter month is the standard rule, but it makes month arithmetic lossy — adding a month and subtracting one does not always return you to the start.
Questions people ask
The things that come up about add months to dates, answered plainly.
What is 31 January plus one month?
28 February, or the 29th in a leap year. The day is clamped to the length of the target month, which is what every date library and every contract means. It is not reversible: subtracting a month from 28 February gives 28 January, not the 31st.
Is a month 30 days?
Not here. Adding a month walks the calendar, so 15 January plus one month is 15 February — 31 days later — and 15 February plus one is 15 March, which is 28. Adding 30 days instead would drift.
Related tools
Move a date forwards or backwards by a span, with the calendar's rules applied.