Python datetime Module

Introduction to Python datetime

Time is a crucial element in programming — whether you're logging events, calculating durations, or scheduling tasks. Python makes handling dates and times easy and intuitive with its built-in datetime module. This tutorial walks you through the foundational concepts of datetime and shows you how to effectively use it in your code.

Importing the datetime Module

To begin working with dates and times, you first need to import the datetime module:

import datetime

This gives you access to classes like datetime, date, time, and timedelta.

Creating a Date Object

The date class lets you represent and manipulate dates (year, month, day).

from datetime import date

d = date(2025, 5, 16)
print(d)

2025-05-16

Explanation: This creates a date object for May 16, 2025. The output is in ISO format (YYYY-MM-DD).

Today's Date

Need to get today’s date? Use the today() method.

from datetime import date

today = date.today()
print("Today is:", today)

Today is: 2025-05-16

Working with datetime Objects

The datetime class combines both date and time into a single object.

from datetime import datetime

now = datetime.now()
print("Current date and time:", now)

Current date and time: 2025-05-16 08:23:45.123456

Notice that it includes the date, hour, minute, second, and microsecond. Perfect for timestamps.

Accessing Individual Components

You can extract parts of the datetime using its attributes.

print("Year:", now.year)
print("Month:", now.month)
print("Day:", now.day)
print("Hour:", now.hour)
print("Minute:", now.minute)
print("Second:", now.second)

Year: 2025
Month: 5
Day: 16
Hour: 8
Minute: 23
Second: 45

Formatting Dates and Times

Use the strftime() method to convert a datetime object into a string with custom formatting.

formatted = now.strftime("%B %d, %Y %I:%M %p")
print("Formatted:", formatted)

Formatted: May 16, 2025 08:23 AM

Note: Use %B for full month name, %d for day, %Y for 4-digit year, etc.

Parsing Strings into datetime Objects

Want to convert a date/time string into a datetime object? Use strptime().

date_str = "2025-05-16 14:30"
dt = datetime.strptime(date_str, "%Y-%m-%d %H:%M")
print(dt)

2025-05-16 14:30:00

Working with Timedelta

timedelta is used to perform date/time arithmetic.

from datetime import timedelta

tomorrow = today + timedelta(days=1)
yesterday = today - timedelta(days=1)

print("Tomorrow:", tomorrow)
print("Yesterday:", yesterday)

Tomorrow: 2025-05-17
Yesterday: 2025-05-15

Measuring Time Durations

Let’s measure how long a piece of code takes to run:

start = datetime.now()
# Simulate processing
for _ in range(10**6):
    pass
end = datetime.now()

duration = end - start
print("Processing time:", duration)

Processing time: 0:00:00.043200

Handling Time Zones

By default, datetime objects are "naive" (no timezone). You can make them aware using pytz or zoneinfo (Python 3.9+).

from datetime import datetime
from zoneinfo import ZoneInfo

dt = datetime.now(ZoneInfo("Asia/Kolkata"))
print(dt)

2025-05-16 13:55:42.123456+05:30

Common Pitfalls & Tips

• Always verify input formats when using strptime(). A mismatch throws ValueError.
• Be mindful of time zones in global applications. Naive datetimes can lead to bugs.
• Use timedelta instead of manual calculations — it handles leap years, daylight saving, etc.
• strftime does not validate format codes — use only valid directives.

Conclusion

The datetime module is one of Python's most powerful and underused tools. From calculating date ranges to logging precise timestamps, it enables developers to write time-sensitive code that is both readable and reliable. By mastering its basics, you're unlocking a vital skill that’s essential for real-world programming.