What is a Month Calculator?

The Month Calculator is a free online tool that calculates the number of months between two dates or adds/subtracts months to a date. Use it to calculate working months, loan months, subscription deadlines, visa durations, lease timeframes, or any other plan that requires accuracy between months.

When you need the number of months between dates you have been counting on a calendar - the month calculator online simply applies jet provost logic (where months do not have the same number of days, they have different endings connected to leap years), to get reliable results and a fast return on calculations.

How Does the Month Calculator Work?

• Choose a mode: Months Between Dates or Add/Subtract Months.
• Enter dates: select a Start Date and End Date for the month difference, or select a Start Date and enter how many months to add/subtract (e.g., +18, −6).
• Options: show months only or months + matching days.
• Click Calculate and get results instantly.

Formula Used in Month Calculations

1. Months between (whole months)
• Months = (Y₂ − Y₁) × 12 + (M₂ − M₁), then subtract 1 if day₂ < day₁ (because the last month isn’t complete). If you choose months + days, the remaining days are the difference between the End Date and the Start Date shifted forward by the whole-month count.
2. Add/Subtract months
• New Date = Start Date ⊕ N months (calendar month arithmetic). If the target month has fewer days than the start day (e.g., 31 → February), the date clamps to the last day of the target month.

Key Benefits of Using This Month Calculator Online

• Fast & accurate: bad manual counting and manual spreadsheet hacks involved.
• Two functional operations: will tell you a total of months between or add and subtract months.
• Handles boundary cases: leap years and end-of-month dates (31 to Feb, etc.).
• Flexible and great output: whole months or months + extra days.
• Works on the internet: works nicely on mobile, tablet and desktop.
• Practical and realistic: good for loan schedules, retainers, warranties, visas, rentals, course terms etc.

Disclaimer

This Month Calculator is intended for educational and informational purposes only. Results are based on standard calendar calculations and may include rounding. Always confirm critical dates or timeframes with official schedules or professional references.