Month Calculator & Counter

1. How to use this month calculator / counter
2. How to calculate the number of months between dates
3. What is X months from today
4. Use as a monthsary calculator
5. How many months is X days?
6. What calendar is used in the month calculator

    How to use this month calculator / counter

Finding out how many months there are between two dates is a common task in time planning and scheduling. For example, it can be used to estimate the number of months available to finish an assignment given some deadline, or to calculate the duration of a long trip or business travel assignment. A month counter can also be useful in analyses that require the calculation of the duration of past events with a known start and end date.

To use the tool, simply enter the start and the end date of the time period. For example, if a work assignment has a deadline on Dec 21, 2025, simply enter the current date in the first field and Dec 21, 2025 and press the button to get an exact count of the number of full months in between, as well as exact duration in months and days.

Similarly, if you are interested in the number of months since a given date in the past, just enter it in the "Start Date" field and select the present date in the second. The months calculator will return the number of full calendar months since, as well as the exact number of months and days since, while accounting for leap years.

Finally, to find out what date is one month, two months, or any number of months from today or from any other date, just use the tool in "Months from date" mode. Enter the number of months and select the date, which can be today or any date in the past or the future.

    How to calculate the number of months between dates

When calculating the number of months between dates separated by a longer period of time, leap year adjustments need to be considered or one can be off by a month or more in certain scenarios. What also makes it difficult is that different months have a different number of days. Some months have 30 days, others 31 days, and February has only 28 days in a typical year and 29 days in a leap year. Using a month counter means you need not worry about these complications.

If calculating the number of months between two dates by hand, the following table can be useful for adjusting the count based on the number of days in any given month:

Neither difference in number of days in each month, nor leap years play a role when calculating the number of full months between two exact dates. For example, the time period between Mar 1 and Oct 1, 2025 is always 7 full months. Likewise, Feb 1 till Jul 31 is always six full months, regardless of leap years. Therefore, finding how many months between dates does not require leap-year adjustments regardless of the time interval in question.

However, the month count for a given number of days before or after a given date may vary depending both on leap years and on which months are covered by the period exactly. For example, 150 days starting from Jan 1 is May 31, 2022. This period consists of exactly 5 months. However, 150 days from Jan 1, 2024 is May 30, 2024, which is just 4 full months, or 4 months and 30 days to be exact. Such complications do not arise if the period does not include a February, or a leap year. In such cases the same time period in days or weeks always contains the same month count.

    What is X months from today

One often needs to check what date is one month from now, or what is five months from now, etc. To answer such questions, one needs to add a month to the current date, or to any other date of interest. This is easier than most people imagine, since in calendar calculations with months the date stays constant, so it becomes an exercise in counting months.

For example, to add 4 months to today, check the number of the current month and add four to it. If the resulting number is greater than 12, subtract 12 from it and roll the number of months that remain into the next year. For example, if today is October 15 (10/15), add 10 + 4 = 14, subtract 12 to get 2. The second month is February, so four months from Oct 15 is Feb 15.

The only exceptions and difficulties are around the final days of the month when the resulting month has fewer days than the current date or date of interest. E.g. if the date is on a 31-st and the resulting month has just 30 days. If the resulting month is a February the issue may occur with the 30-th and 29-th, depending on whether it is a non-leap or leap year. For example, six months from August 30 would naively result in February 30, but since there is no such date, one needs to roll into the next month to account for the irregular number of days in a month. If one wants to calculate six months from Aug 30, it would result in Mar 2 in the next year if the next year is non-leap, or Mar 1 if it is a leap year.

    Use as a monthsary calculator

Monthsary celebrations and commemorations are becoming increasingly popular, especially romantic ones. A given "End date" would be your monthsary if "Exact time between dates" output says "X months, 0 days". X would be the exact number of months since your relationship began. If the number of days is greater than zero, then the specified "End date" is not your monthsary, but in this case you will see how many days remain until it occurs.

What is a monthsary?

A monthsary, short for "monthly anniversary", is similar to an anniversary but counts the months between an event and present time. Whereas an anniversary marks full years between events, a monthsary is recognized and celebrated when a specific number of months have elapsed, e.g. one month, three months, ten months, etc. Romantic monthsaries are therefore monthly commemorations of the date on which a couple first got together.

    How many months is X days?

Sometimes people want to convert a number of days into months. In contracts, agreements, and laws, time may be specified as the number of days since an event instead of as a fixed date. However, there can only be an approximate answer to this question due to the different durations of each month, as shown in the table above.

For example, "How many months is 150 days" is a common question without an exact answer. On average, 150 days equals just under 5 months. The average month is 30.5 days, so five months is 152.5 days on average. However, if the 150 day range includes February, then 150 days may end up being exactly five months.

Other commonly encountered numbers are 180 days which is approximately six months, and 270 days, which is approximately nine months. Here is a handy table for quick reference. For any type of precise calculation, use the month calculator above.

    What calendar is used in the month calculator

This calendar month calculator is based on the Gregorian calendar. A solar calendar named after Pope Gregory XIII, it was first introduced in Europe in 1582. Today it sees use in most countries in Europe as well as countries settled or ruled by Europeans during the past centuries such as America. The Gregorian calendar contains 365 days in a typical year and adds an extra day every four years for a total of 366 days to align the calendar with astronomical events related to Earth's rotation around the Sun. Those years are called "leap years".

The Gregorian calendar is used by businesses across the world. In certain jurisdictions it coexists with local calendars.