How to Get First and Last Day of Month in Python

Use Python's datetime module to get the first day by setting the day to 1, and use the calendar.monthrange() function to find the last day of the month. Combine these to get both dates easily.

Syntax

To get the first day of a month, create a datetime.date object with the year, month, and day set to 1.

To get the last day, use calendar.monthrange(year, month) which returns a tuple where the second value is the number of days in that month.

python

import datetime
import calendar

year = 2024
month = 6

first_day = datetime.date(year, month, 1)
last_day = datetime.date(year, month, calendar.monthrange(year, month)[1])

Example

This example shows how to print the first and last day of June 2024.

python

import datetime
import calendar

year = 2024
month = 6

first_day = datetime.date(year, month, 1)
last_day = datetime.date(year, month, calendar.monthrange(year, month)[1])

print("First day:", first_day)
print("Last day:", last_day)

Output

First day: 2024-06-01
Last day: 2024-06-30

Common Pitfalls

• Trying to get the last day by adding days manually can cause errors because months have different lengths.
• Using datetime.datetime.now() without extracting year and month can lead to wrong results if you want a specific month.
• Not importing the calendar module will cause errors when calling monthrange().

python

import datetime

# Wrong: Adding 30 days always (incorrect for months with 28, 29, or 31 days)
start_date = datetime.date(2024, 2, 1)
wrong_last_day = start_date + datetime.timedelta(days=30)

# Right: Using calendar.monthrange
import calendar
last_day = datetime.date(2024, 2, calendar.monthrange(2024, 2)[1])

print("Wrong last day:", wrong_last_day)
print("Correct last day:", last_day)

Output

Wrong last day: 2024-03-02
Correct last day: 2024-02-29

Quick Reference

Summary tips to get first and last day of any month:

• First day: datetime.date(year, month, 1)
• Last day: datetime.date(year, month, calendar.monthrange(year, month)[1])
• Always import calendar for monthrange()

Key Takeaways

Use datetime.date(year, month, 1) to get the first day of the month.

Use calendar.monthrange(year, month)[1] to find the last day number of the month.

Avoid manually adding days to find month ends because months vary in length.

Always import the calendar module when using monthrange.

This method works for any year and month, including leap years.