You can use one of the following two methods to calculate the number of months between two dates in R:

**Method 1: Calculate Number of Whole Months Between Dates**

**library(lubridate)
interval(first_date, second_date) %/% months(1)
**

**Method 2: Calculate Number of Partial Months (With Decimal Places) Between Dates**

**library(lubridate)
interval(first_date, second_date) %/% days(1) / (365/12)**

The following examples show how to use each method in practice.

**Example 1: Calculate Number of Whole Months Between Dates**

We can use the following code to calculate the number of whole months between two dates in R:

**library(lubridate)
#define dates
first_date <- as.Date('2022-05-01')
second_date <- as.Date('2022-09-04')
#calculate difference between dates in months
diff <- interval(first_date, second_date) %/% months(1)
#view difference
diff
[1] 4
**

We can see that there are four **whole** months between the two dates that we specified.

**Example 2: Calculate Number of Partial Months Between Dates**

We can use the following code to calculate the number of partial months between two dates in R:

**library(lubridate)
#define dates
first_date <- as.Date('2022-05-01')
second_date <- as.Date('2022-09-04')
#calculate difference between dates in partial months
diff <- interval(first_date, second_date) %/% days(1) / (365/12)
#view difference
diff
[1] 4.142466
**

We can see that there are **4.142466** months between the two dates that we specified.

Note how this method is more specific than the previous method because it tells us the number of **partial** months between the dates as well.

Depending on your situation, you may prefer to use one of these methods over the other.

**Note**: Both methods use functions from the lubridate package in R. If you don’t already have this package installed, you can run the following in your R console:

**install.packages('lubridate')
**

You can also find the complete documentation for the **interval()** function we used here.

**Additional Resources**

The following tutorials explain how to perform other common tasks in R:

How to Convert a Character to a Timestamp in R

How to Convert Factor to Date in R

How to Extract Year from Date in R