Subtract Days, Months & Years from datetime Object in Python (3 Examples)

In this tutorial, I’ll illustrate how to get X days, months, and years earlier as a certain datetime object in Python.

Table of contents:

Let’s get started…

Example Data & Add-On Libraries

We first need to import the datetime module:

import datetime                                           # Import datetime module to Python

Furthermore, we need to import the relativedelta function, as you can see below:

from dateutil.relativedelta import relativedelta          # Import relativedelta

Now, we are ready to create an example datetime object:

my_datetime = datetime.datetime(2023, 6, 20, 7, 35, 18)   # Constructing example datetime
print(my_datetime)                                        # Return example datetime
#2023-06-20 07:35:18

Example 1: Get datetime X Days Ago

In the first example, I’ll explain how to subtract a specific number of days from our datetime object.

For this task, we can use the relativedelta function and the days argument, as you can see here:

my_date_days = my_datetime - relativedelta(days = 12)     # Calculate 12 days earlier
print(my_date_days)                                       # Return new datetime object
# 2023-06-08 07:35:18

The previous output of the Python console shows that we have created a new data object called my_date_days, which shows our input date and time 12 days earlier.

Example 2: Get datetime X Months Ago

In Example 2, I’ll demonstrate how to create a date and time object that is X months before our input data.

To get there, we can apply the relativedelta function once again, but his time combined with the months argument.

my_date_months = my_datetime - relativedelta(months = 4)  # Calculate 4 months earlier
print(my_date_months)                                     # Return new datetime object
# 2023-02-20 07:35:18

The new datetime object called my_date_months has been created and shows the date 4 months earlier than in our input date.

Example 3: Get datetime X Years Ago

The last example explains how to get a date object, which returns our example date X Years ago.

To accomplish this, we simply apply the relativedelta function within the years argument:

my_date_years = my_datetime - relativedelta(years = 8)    # Calculate 8 years earlier
print(my_date_years)                                      # Return new datetime object
# 2015-06-20 07:35:18

Considering the output above, the date in the new datetime object is 8 years earlier compared to the input object.

Video, Further Resources & Summary

Would you like to learn more about the subtraction of a particular number of days, months, and years from a datetime? Then I recommend watching the following video on my YouTube channel. I illustrate the Python code of this article in the video:

The YouTube video will be added soon.

Furthermore, you might want to have a look at some other articles on this website. You can find a selection of articles on related topics such as dates, time objects, and data objects below.

• Convert Epoch Time to datetime Object & Vice Versa in Python
• Convert datetime Object to Date Only String in Python
• Convert datetime Object to Local Time Zone in Python
• Add Days, Months & Years to datetime Object in Python
• The Python Programming Language

To summarize: In this tutorial, you have learned how to subtract a specific number of days, months, and years from a date and time object to get a previous date and time in the Python programming language. Let me know in the comments, in case you have further comments and/or questions. Furthermore, please subscribe to my email newsletter in order to get updates on the newest articles.

This page was created in collaboration with Matthias Bäuerlen. Have a look at Matthias’ author page to get more information about his professional background, a list of all his tutorials, as well as an overview on his other tasks on Statistics Globe.