Date & Time

Introduction

Almost every real program eventually needs to deal with dates and times — logging when something happened, calculating someone's age, scheduling a reminder, or measuring how long a task took. Handling this manually with plain numbers is error-prone, since months have different lengths and years can be leap years.

Python's built-in datetime module handles all of this complexity for you. This lesson covers how to get the current date and time, build specific dates, format and parse them, and perform date arithmetic.

The datetime Module

The datetime module is part of Python's standard library, so no installation is required — just import it. It provides several classes for working with dates and times, the most commonly used being datetime itself.

from datetime import datetime

print(type(datetime.now()))

<class 'datetime.datetime'>

Getting the Current Date and Time

datetime.now() returns a datetime object representing the current moment, including the date and time down to microseconds.

from datetime import datetime

current = datetime.now()
print(current)
print(current.year, current.month, current.day)
print(current.hour, current.minute, current.second)

2026-07-25 09:41:12.583201
2026 7 25
9 41 12

The exact numbers will differ every time you run this, since it reflects the moment the code executes. Each part of the date and time is available as a separate attribute on the object.

Creating a Specific Date

You are not limited to "right now" — you can build a datetime object for any date and time by passing the year, month, and day (and optionally hour, minute, second) directly.

from datetime import datetime

launch_day = datetime(2026, 1, 1)
print(launch_day)

meeting = datetime(2026, 3, 15, 14, 30)
print(meeting)

2026-01-01 00:00:00
2026-03-15 14:30:00

If you omit the time, it defaults to midnight (00:00:00). This is useful when you only care about the date and not a specific time.

date, time, and datetime: When to Use Which

Sometimes you only need a calendar date without a time, or a time of day without a specific date. The datetime module provides date and time classes for exactly these cases.

from datetime import date, time, datetime

just_date = date(2026, 12, 25)
print(just_date)

just_time = time(18, 30, 0)
print(just_time)

combined = datetime.combine(just_date, just_time)
print(combined)

2026-12-25
18:30:00
2026-12-25 18:30:00

Formatting Dates with strftime()

strftime() ("string format time") converts a datetime object into a custom-formatted string, using special codes to represent each part of the date.

from datetime import datetime

now = datetime(2026, 7, 25, 9, 41)

print(now.strftime("%Y-%m-%d"))
print(now.strftime("%d/%m/%Y"))
print(now.strftime("%B %d, %Y"))
print(now.strftime("%A, %H:%M"))

2026-07-25
25/07/2026
July 25, 2026
Saturday, 09:41

Parsing Strings with strptime()

strptime() ("string parse time") does the opposite of strftime() — it converts a string into a datetime object, as long as you tell it exactly what format the string is in.

from datetime import datetime

text = "25-07-2026"
parsed = datetime.strptime(text, "%d-%m-%Y")
print(parsed)
print(type(parsed))

2026-07-25 00:00:00
<class 'datetime.datetime'>

The format string passed to strptime() must match the layout of the input string exactly, or Python raises a ValueError.

from datetime import datetime

try:
    datetime.strptime("25-07-2026", "%Y-%m-%d")
except ValueError as e:
    print("Error:", e)

Error: time data '25-07-2026' does not match format '%Y-%m-%d'

Date Arithmetic with timedelta

A timedelta object represents a span of time — like "3 days" or "2 hours." You can add or subtract a timedelta from a datetime to shift it forward or backward, and subtracting two datetime objects gives you a timedelta automatically.

from datetime import datetime, timedelta

today = datetime(2026, 7, 25)

next_week = today + timedelta(days=7)
print("One week later:", next_week)

last_month = today - timedelta(days=30)
print("30 days earlier:", last_month)

One week later: 2026-08-01 00:00:00
30 days earlier: 2026-06-25 00:00:00

from datetime import datetime

start = datetime(2026, 1, 1)
end = datetime(2026, 7, 25)

difference = end - start
print(difference)
print("Days between:", difference.days)

Days between: 205
205 days, 0:00:00

Common Mistakes

Best Practices

Frequently Asked Questions

Key Takeaways

Summary

The datetime module gives Python a reliable, built-in way to represent, format, parse, and calculate with dates and times, without needing to manually account for varying month lengths or leap years.

In this lesson, you learned how to get the current date and time, build specific dates, format and parse dates as strings, and perform date arithmetic using timedelta.