Month Calculator & Counter

Created by Georgi Georgiev
Last updated: Oct 13, 2026

1. How to use this month calculator
2. How to calculate months between dates
3. What is X months from today
4. How many months since Month & Year
5. Use as a monthsary calculator
6. How many months is X days?
7. What calendar is used in the calculator

    How to use this month calculator

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 how many months are 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, 2026, simply enter the current date in the first field and Dec 21, 2026 and press the button to get an exact count of the number of full months in between, as well as time duration accurate to the day.

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.

To find out how many months ago was a given time use the "months since a given month & year" option. For example, to check how many months ago was August last year, just select the desired one from the drop down and specify the year.

Finally, to find out what date is a given 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 today or any date in the past or the future.

    How to calculate months between dates

When calculating time 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 have 30 days, others 31 days, and February has only 28 days in a typical year and 29 days in a leap year.

If doing the time math 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 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, 2026 is always 7 full months. Likewise, Feb 1 till Jul 31 is always six full months, regardless of leap years.

However, the month count for a given number of days before or after a given date may vary depending on leap years and which months are within the period. 150 days starting from Jan 1 is May 31, 2026 and 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 only arise if the period includes February in a leap year.

    What is X months from today

To check what date is one month from today, or what is five months from now is to add a month to the current date, or to any other date. This is easy since the date stays constant and it is just about 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 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.

There are exceptions and difficulties only around the final days of the month when the resulting month has fewer days than the date of interest. E.g. if it is 31-st and the resulting month has just 30 days. If the resulting month is a February this issue occurs with the 30-th and 29-th as well. 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.

    How many months since Month & Year

Instead of exact date calculations, one often needs just a round number of calendar months between now and a time in the past. For example, if you've been on vacation in July, you might be wondering how many months has it been since July this year. Or, if there had been a major life event for you in September 2020, you might be wondering how many months ago September 2020 was.

These calculations are fairly simple within a single year. For example, November is the eleventh month of the year and July is the seventh. If today is November, the number of months since July is therefore 11-7-1 = 3 full calendar months. We subtract one at the end to account for the fact that the current month has not yet passed. For multi-year calculations just add 12 months for every year between now and then.

    Use as a monthsary calculator

Monthsary celebrations and commemorations are becoming increasingly popular, especially romantic ones, but also for babies. To find your monthsary by date, switch to "monthsary" mode, enter the date of the event in "Event date". It could be the date when you started a relationship, the date your baby was born, and so on. Click "calculate" and the monthsary calculator will output the calendar date of your next monthsary, the number of days until it comes, and how many months since your relationship began.

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?

In contracts, agreements, and laws, time may be specified as the number of days since an event instead of as a fixed date. Only an approximate answer to how many months this represents is possible due to the different durations of each month, as shown in the table above.

Take for example, the question "How many months is 150 days?". 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.

See the table for other commonly encountered numbers. For any type of precise calculation, use the month counter tool.

    What calendar is used in the 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.