MonthstepCalendar months, with the rule in view

FREE CALENDAR MONTH CALCULATOR

Move by months.
Keep the rule visible.

Find the date a whole number of months before or after a source date. Choose what happens when the target month has no matching day.

A month is a calendar step, not a fixed number of days.

Choose your calendar step

Month shift inputs
YYYY-MM-DD. A valid Gregorian date in years 0001–9999.
Use 1 to move one month later, −1 to move earlier, or 0 to keep the date. Type an ordinary hyphen minus for negative input.
For January 31 plus one month, the first rule uses February’s last day. Reject gives an unavailable result.

CURRENT CALENDAR RESULT

The missing day deserves an explicit answer.

February does not contain January’s day 31. Under Use the target month’s last day if needed, January 31, 2024 plus one month becomes February 29. Under Reject missing day, the result is unavailable. Neither rule invents February 31 or rolls extra days into March.

April 30 plus one month becomes May 30. The tool does not preserve “last day of the month” as a special instruction. A valid day number is kept whenever it exists in the destination month.

Read the calculation rules →Follow the worked examples →