Date & Time#

Python handles dates and times through the time and datetime modules.

Module time#

The time module provides functions for working with time values represented as seconds since the epoch (January 1, 1970).

Time Structure#

time.localtime() returns a named tuple with 9 attributes:

Index	Attribute	Description	Values
0	tm_year	4-digit year	e.g. 2025
1	tm_mon	Month	1–12
2	tm_mday	Day	1–31
3	tm_hour	Hour	0–23
4	tm_min	Minute	0–59
5	tm_sec	Second	0–59
6	tm_wday	Day of week	0–6 (Monday=0)
7	tm_yday	Day of year	1–366
8	tm_isdst	Daylight saving	-1, 0, 1

Format Directives#

Directive	Meaning
`%a` / `%A`	Abbreviated / full weekday name
`%b` / `%B`	Abbreviated / full month name
`%d`	Day of month (01–31)
`%H` / `%I`	Hour: 24h (00–23) / 12h (01–12)
`%j`	Day of year (001–366)
`%m`	Month (01–12)
`%M`	Minute (00–59)
`%S`	Second (00–59)
`%y` / `%Y`	Year without / with century
`%Z`	Time zone name

Main Functions#

Function	Description
`time.localtime()`	Current local time as a named tuple
`time.time()`	Current time as seconds since epoch (float)
`time.strftime(format, t)`	Format a time tuple as a string
`time.sleep(secs)`	Pause execution for the given number of seconds

>>> import time
>>> time.localtime()
time.struct_time(tm_year=2025, tm_mon=3, tm_mday=4, ...)
>>> time.strftime("%a, %d %b %Y %H:%M:%S", time.localtime())
'Tue, 04 Mar 2025 11:56:30'

Measuring Elapsed Time#

import time

print(time.strftime("%H:%M:%S"))
start = time.time()

# Simulate a process
time.sleep(3.7)

elapsed = time.time() - start
hours = int(elapsed // 3600)
minutes = int((elapsed % 3600) // 60)
seconds = int(elapsed % 60)

print(f"Time: {time.strftime('%H:%M:%S')}")
print(f"Processing time: {hours:02d}:{minutes:02d}:{seconds:02d}")

Module datetime#

The datetime module provides classes for manipulating dates and times.

Main Classes#

Class	Description
`datetime.date(year, month, day)`	A date (no time component)
`datetime.time(hour, minute, second, microsecond)`	A time (no date component)
`datetime.datetime(year, month, day, hour, minute, second)`	Combined date and time
`datetime.timedelta(days, seconds, ...)`	A duration between two dates/times

Main Methods#

Method	Description
`datetime.date.today()`	Current local date
`datetime.datetime.now()`	Current local date and time
`obj.replace(year=..., month=...)`	Return a copy with specified fields replaced
`obj.isoformat()`	ISO 8601 string (YYYY-MM-DDTHH:MM:SS)
`obj.year`, `.month`, `.day`, `.hour`, etc.	Access individual components
`obj.weekday()`	Day of week (Monday=0, Sunday=6)

Examples#

>>> import datetime
>>> today = datetime.date(2025, 8, 6)
>>> one_day = datetime.timedelta(days=1)
>>> today + one_day
datetime.date(2025, 8, 7)

>>> birth = datetime.datetime(1974, 2, 7, 20, 45, 50)
>>> now = datetime.datetime(2025, 3, 16, 10, 38, 2)
>>> diff = now - birth
>>> diff.days
18665
>>> diff.seconds
49932

>>> years = diff.days // 365
>>> remaining_days = diff.days % 365
>>> hours = diff.seconds // 3600
>>> minutes = (diff.seconds % 3600) // 60
>>> print(f"{years} years, {remaining_days} days, {hours}h {minutes}min")
51 years, 40 days, 13h 52min