How to add Months to a Date in Python

Accurately manipulating dates and times is a common task in software development.

This guide focuses specifically on how to add months to dates in Python, a task that requires careful handling of varying month lengths and year rollovers. We'll leverage the powerful dateutil library to simplify these calculations and ensure accurate results.

Adding Months to a date Object

The dateutil.relativedelta class is designed for flexible date and time arithmetic, especially when dealing with months. Here’s how to add a specific number of months to a date object:

from datetime import date
from dateutil.relativedelta import relativedelta

initial_date = date(2024, 6, 24)
new_date = initial_date + relativedelta(months=3)
print(new_date)  # Output: 2024-09-24

note

The relativedelta(months=N) syntax ensures that month calculations are handled correctly, considering different month lengths and potential year changes. Always use months=N (where N is the number of months) for clarity. The + operator is overloaded to allow direct addition between date/datetime objects and relativedelta objects.

Adding Months to the Current Date

To perform this operation relative to today’s date, use date.today() and then apply relativedelta:

from datetime import date
from dateutil.relativedelta import relativedelta

today = date.today()
future_date = today + relativedelta(months=2)
print(future_date)  # Output: (Varies based on current date)

Working with datetime Objects

datetime objects encapsulate both date and time information. relativedelta seamlessly handles month additions with these objects.

1. Extracting the Date Component

If you need only the date part after modification, use the .date() method:

from datetime import datetime
from dateutil.relativedelta import relativedelta

now = datetime.now()
future_datetime = now + relativedelta(months=3)
future_date = future_datetime.date()
print(future_date)  # Output: (Date three months in the future)

2. Formatting datetime Output

Use f-strings with format specifiers to display dates and times as needed:

from datetime import datetime
from dateutil.relativedelta import relativedelta

now = datetime.now()
future_datetime = now + relativedelta(months=3)
formatted_datetime = f'{future_datetime:%Y-%m-%d %H:%M:%S}'
print(formatted_datetime)  # Output: (Formatted datetime, e.g., 2024-01-26 10:30:00)

note

Refer to Python’s strftime() documentation for more detailed format codes to customize your date and time strings.

Parsing Date Strings and Adding Months

Often you'll start with dates represented as strings. Use datetime.strptime() to parse strings and then perform month calculations:

from datetime import datetime
from dateutil.relativedelta import relativedelta

date_str = '09-24-2023'  #Format is MM-DD-YYYY
date_obj = datetime.strptime(date_str, '%m-%d-%Y')
future_date = date_obj + relativedelta(months=2)
print(future_date)   # Output: 2023-11-24 00:00:00

note

The format string provided to strptime must match the format of your input date string exactly. Inconsistent formats will lead to errors.

Adding Months Using datetime.today()

datetime.today() provides both date and time information for the current moment, enabling you to perform month calculations:

from datetime import datetime
from dateutil.relativedelta import relativedelta

now_datetime = datetime.today()
future_datetime = now_datetime + relativedelta(months=5)
print(future_datetime) # Output (Current datetime plus 5 months)

Installation of python-dateutil

If you don't have python-dateutil installed, use pip:

pip install python-dateutil
#or using pip3
pip3 install python-dateutil