Date & Calendar Math

Month Calculator

Add or subtract months from a date with explicit month-end clamping rules (e.g. Jan 31 + 1 month).

Calculation Result

Instant
2026-12-29
Tuesday (Rule: Clamped to month end)
Result Date
2026-12-29
Day of Week
Tuesday
Operation
+3 Months
Month End Clamped?
No

About Month Calculator

Add or subtract calendar months with clearly documented handling for shorter target months.

Calculation Methodology & Formula

Applies the target month offset. When the starting day exceeds the total days of the destination month (such as January 31 + 1 month), the calculator clamps the result to the last valid day of that month (February 28/29) or supports standard overflow.

How to Use This Calculator

  1. Enter your starting date.
  2. Enter the number of months and select Add or Subtract.
  3. Choose the month-end rule (Clamp to month end or Overflow).
  4. Click "Calculate Date".

Frequently Asked Questions

Related Calculators

Add Days to Date Calculator

Add any number of calendar days to a starting date to find the future date and day of the week.

Open Tool →

Year Difference Calculator

Calculate completed calendar years and remaining months/days between two years or dates.

Open Tool →