Add Months to Date
The Add Months to Date Calculator finds the date a given number of months before or after a start date. Enter a start date and the number of months to add (use a negative number to go backwards), and it returns the resulting calendar date.
Formula
Result = Date with (Start Month + Months Added)
- The result keeps the same day-of-month where possible, shifting the month and year by the number of months you add.
- Use a negative number of months to find a date in the past.
- If the start day does not exist in the target month (e.g. the 31st), the date rolls over into the following month, matching standard date arithmetic.
- Leap years and varying month lengths are handled automatically.
Example Calculation
Inputs
- Start Date: 2026-06-23
- Months to Add: 6
Adding 6 months to 23 June 2026 gives 23 December 2026.
Frequently asked questions
How do I subtract months instead of adding?
Enter a negative number in the 'Months to Add' field, for example -3 to go three months back.
What happens if the day doesn't exist in the target month?
For example, adding one month to 31 January rolls into early March, following standard JavaScript date arithmetic.
Does it handle leap years?
Yes. Month and year boundaries, including February in leap years, are handled automatically.
Can I add more than 12 months?
Yes. Any whole number of months works; the calculator rolls the year forward or backward as needed.
Is the start date included?
The result is measured from the start date, keeping the same day number in the new month wherever possible.