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Month Calculator

Count the months between two dates in whole months and days, or add and subtract months from a date. Handles short months correctly. Free.

Counting calendar months

Months have different lengths, so counting them isn't just dividing days by 30. This calculator counts whole calendar months and then the days left over, the way contracts and ages are usually counted. From 15 March to 15 November is exactly 8 months. Adding months keeps the day of the month where it can: 31 January plus one month is 28 February (or 29 in a leap year). A decimal month count is also shown, based on an average month of 30.44 days.

How to use it

  1. 1

    Choose the calculation

    Months between dates, or add months to a date.

  2. 2

    Enter the dates

    Or a number of months to add.

  3. 3

    Read the result

    Months and days, plus years, weeks and days.

Frequently asked questions

How many months between two dates?

Count the full months from the start date, then the remaining days.

What is 31 January plus one month?

28 February, or 29 February in a leap year, because February has no 31st.

How long is an average month?

30.44 days (365.25 ÷ 12).

Is anything stored?

No. The calculation runs in your browser.

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