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The date type in Python

How to work with dates in Python using datetime.date: creating dates, reading parts of a date, formatting with strftime and isoformat, date arithmetic with timedelta, and invalid dates.

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Python has no built-in date value like int or str. Dates live in the standard library module datetime, and the type you usually need is date. A date holds a year, a month and a day: no time of day, no time zone. For a time, use datetime, a separate topic.

Every example here was run with Python 3.13 and checked against the date objects docs.

Creating a date

Import the class, then pass the year, month and day as integers:

from datetime import date

d = date(2026, 10, 11)
print(d)
print(repr(d))

2026-10-11
datetime.date(2026, 10, 11)

print shows the ISO format (YYYY-MM-DD). repr shows how you’d write the object in code.

All three arguments are required and must be in range (month 1 to 12, day 1 up to the month’s length), or you get a ValueError:

date(2026, 2, 30)

ValueError: day is out of range for month

To get today’s date, call date.today(). Its output changes daily, so it isn’t printed here.

Reading parts of a date

print(d.year, d.month, d.day)
print(d.weekday(), d.isoweekday())

2026 10 11
6 7

weekday() counts Monday as 0 (Sunday is 6), isoweekday() counts Monday as 1 (Sunday is 7). Pick one and stick to it.

Formatting a date

strftime builds text from a format string. The codes start with %:

print(d.strftime("%d/%m/%Y"))
print(d.strftime("%A"))
print(d.isoformat())

11/10/2026
Sunday
2026-10-11

%d, %m and %Y are the day, month and year. %A is the weekday name. The full list of codes is in the docs for strftime.

To read a date from text, use fromisoformat. It accepts the ISO format:

print(date.fromisoformat("2026-01-01"))

2026-01-01

For other formats, such as 11/10/2026, use datetime.strptime.

Date arithmetic

Add or subtract a timedelta, which represents a length of time:

from datetime import timedelta

print(d + timedelta(days=30))

2026-11-10

Subtracting two dates gives a timedelta:

print(d - date(2026, 1, 1))
print((d - date(2026, 1, 1)).days)

283 days, 0:00:00
283

.days returns the number of days as an integer.

Dates can be compared with <, > and ==:

print(d > date(2026, 1, 1))

True

Common mistakes

  • Using a string where a date is needed. "2026-10-11" > "2026-01-01" compares text. It only works by accident for ISO format. Convert with fromisoformat first.

What’s next

Next: lists, which hold many values in one variable.

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