Dates & Times

Python - A Quick Start for existing Programers

3 min read

Published Sep 16 2025, updated Sep 30 2025

Python

Python provides the datetime module for working with dates, times, and timestamps. This module has the following objects that you can import:

date - represents a calendar date. Use if you only care about year, month, day.
time - represents a time of day. Use if you only care about hour, minute, second.
datetime - represents a combined date and time. Use for everything together and arithmetic.
timedelta - represents a duration or difference between dates/times. Use for durations and date/time calculations.

Import the objects required:

from datetime import date, time, datetime, timedelta

date object

Creation:

# Create a date using year, month, day

d1 = date(2025, 9, 15)

print("Date from year, month, day:", d1)

# Get today's date

d2 = date.today()

print("Today's date:", d2)

# Create a date from a timestamp (seconds since epoch)

ts = 1694764800 # example timestamp

d3 = date.fromtimestamp(ts)

print("Date from timestamp:", d3)

# Create a date from an ISO string

iso_str = "2025-09-15"

d4 = date.fromisoformat(iso_str)

print("Date from ISO string:", d4)

Attributes:

year, month, day

Methods:

today() → current date
fromtimestamp(ts) → date from Unix timestamp
weekday() → 0=Monday … 6=Sunday
isoweekday() → 1=Monday … 7=Sunday
isoformat() → 'YYYY-MM-DD'
replace(year=…, month=…, day=…) → return new date with replaced fields
timetuple() → struct_time tuple

Operations:

date1 - date2 → timedelta
Comparisons: <, >, ==, etc.

time object

Creation:

# Create a time using hour, minute, second, microsecond

t1 = time(14, 30, 45)

print("\nTime from h,m,s:", t1)

# Create a time with microseconds

t2 = time(14, 30, 45, 123456)

print("Time with microseconds:", t2)

# Replace components of a time object

t3 = t1.replace(hour=16, minute=0)

print("Time after replace:", t3)

# Get current time as a time object

current_time = datetime.now().time()

print("Current time:", current_time)

# Get current UTC time as a time object

current_utc_time = datetime.utcnow().time()

print("Current UTC time:", current_utc_time)

Attributes:

hour, minute, second, microsecond, tzinfo

Methods:

isoformat() → 'HH:MM:SS.microseconds'
replace(hour=…, minute=…, second=…) → new time with replaced fields

Note: time objects do not support arithmetic (use datetime + timedelta instead).

datetime object

Creation:

# Create datetime using year, month, day, hour, minute, second, microsecond

dt1 = datetime(2025, 9, 15, 14, 30, 45)

print("\nDatetime from components:", dt1)

# Current local datetime

dt2 = datetime.now()

print("Current local datetime:", dt2)

# Current UTC datetime

dt3 = datetime.utcnow()

print("Current UTC datetime:", dt3)

# Create datetime from timestamp

dt4 = datetime.fromtimestamp(ts)

print("Datetime from timestamp:", dt4)

# Create datetime from ISO string

dt5 = datetime.fromisoformat("2025-09-15T14:30:45")

print("Datetime from ISO string:", dt5)

# Create datetime from a date and time object

d1 = date(2025, 9, 15)

t1 = time(14, 30, 45)

dt6 = datetime.combine(d1, t1)

print("Datetime from date + time objects:", dt6)

# Replace components of datetime

dt7 = dt1.replace(year=2026, hour=16)

print("Datetime after replace:", dt7)

Attributes:

year, month, day, hour, minute, second, microsecond, tzinfo

Methods:

date() → date part
time() → time part
replace(...) → replace components
isoformat() → 'YYYY-MM-DDTHH:MM:SS.microseconds'
strftime(format) → formatted string
strptime(string, format) → parse string into datetime
timestamp() → seconds since epoch

Operations:

datetime ± timedelta → new datetime
datetime1 - datetime2 → timedelta
Comparisons: <, >, ==, etc.

timedelta object

Creation:

timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)

Attributes:

days, seconds, microseconds

Methods:

total_seconds() → total duration in seconds

Operations:

datetime + timedelta → new datetime
datetime - timedelta → new datetime
timedelta ± timedelta → new timedelta
Comparisons: <, >, ==, etc.

Formatting output of datetime

The following methods use the codes below:

.strftime() to format a datetime into a string.
.strptime() with the same codes to parse a string back into datetime.
isoformat() is a quick way for standardised output: 2025-09-15T14:30:45.

Code	Meaning	Example
`%Y`	Year (4 digits)	`2025`
`%y`	Year (2 digits)	`25`
`%m`	Month (01–12)	`09`
`%B`	Full month name	`September`
`%b`	Abbreviated month name	`Sep`
`%d`	Day of month (01–31)	`15`
`%j`	Day of year (001–366)	`258`
`%U`	Week number of year (Sunday as first day, 00–53)	`37`
`%W`	Week number of year (Monday as first day, 00–53)	`37`
`%V`	ISO week number (01–53)	`38`
`%A`	Full weekday name	`Monday`
`%a`	Abbreviated weekday name	`Mon`
`%w`	Weekday as number (0=Sunday, 6=Saturday)	`1`
`%x`	Locale’s date representation	`09/15/25`
`%H`	Hour (00–23)	`14`
`%I`	Hour (01–12)	`02`
`%p`	AM/PM	`PM`
`%M`	Minute (00–59)	`30`
`%S`	Second (00–59)	`45`
`%f`	Microsecond (000000–999999)	`123456`
`%X`	Locale’s time representation	`14:30:45`
`%c`	Locale’s date and time	`Mon Sep 15 14:30:45 2025`
`%x`	Locale’s date	`09/15/25`
`%X`	Locale’s time	`14:30:45`
`%%`	A literal `%` character	`%`

Examples:

from datetime import datetime

# Get current datetime

now = datetime.now()

print("Original datetime object:", now)

print("\n# Common formats")

# Full date & time

print("Default ISO:", now.isoformat())

# 2025-09-15T14:30:45.123456

print("YYYY-MM-DD HH:MM:SS:", now.strftime("%Y-%m-%d %H:%M:%S"))

print("DD/MM/YYYY HH:MM:", now.strftime("%d/%m/%Y %H:%M"))

# Date only

print("Year-Month-Day:", now.strftime("%Y-%m-%d"))

print("Day-Month-Year:", now.strftime("%d-%m-%Y"))

print("Month/Day/Year:", now.strftime("%m/%d/%Y"))

# Time only

print("24-hour format:", now.strftime("%H:%M:%S"))

print("12-hour format:", now.strftime("%I:%M:%S %p"))

# Named components

print("Weekday (short):", now.strftime("%a"))

# Mon

print("Weekday (full):", now.strftime("%A"))

# Monday

print("Month (short):", now.strftime("%b"))

# Sep

print("Month (full):", now.strftime("%B"))

# September

# Other useful pieces

print("Day of month:", now.strftime("%d"))

# 15

print("Day of year:", now.strftime("%j"))

# 258

print("Week number:", now.strftime("%U"))

# Week number of year (Sunday start)

print("ISO Week number:", now.strftime("%V"))

# Week number (ISO standard)

print("Year (2-digit):", now.strftime("%y"))

print("Year (4-digit):", now.strftime("%Y"))

# Combining

print("\nCustom combined format:", now.strftime("Today is %A, %B %d, %Y at %I:%M %p"))

Demo of date and time objects

from datetime import date, time, datetime, timedelta

# 1. Date

d = date(2025, 9, 15)

print("Date object:", d)

today = date.today()

print("Today's date:", today)

print("Year:", today.year, "Month:", today.month, "Day:", today.day)

# 2. Time

t = time(14, 30, 45)

print("\nTime object:", t)

print("Hour:", t.hour, "Minute:", t.minute, "Second:", t.second)

# 3. Datetime (date + time)

dt = datetime(2025, 9, 15, 14, 30, 45)

print("\nDatetime object:", dt)

now = datetime.now()

print("Current datetime:", now)

print("Components:", now.year, now.month, now.day, now.hour, now.minute, now.second)

# 4. Timedelta (date/time arithmetic)

delta = timedelta(days=5, hours=3)

future = now + delta

past = now - delta

print("\nTimedelta:", delta)

print("5 days and 3 hours later:", future)

print("5 days and 3 hours earlier:", past)

# 5. Formatting (datetime -> string)

formatted = now.strftime("%Y-%m-%d %H:%M:%S")

print("\nFormatted datetime string:", formatted)

# 6. Parsing (string -> datetime)

dt_str = "2025-09-15 14:30:45"

parsed_dt = datetime.strptime(dt_str, "%Y-%m-%d %H:%M:%S")

print("Parsed datetime from string:", parsed_dt)

# 7. Comparisons

dt1 = datetime(2025, 1, 1)

dt2 = datetime(2025, 12, 31)

print("\nIs dt1 < dt2?", dt1 < dt2)

print("Is today == now.date()?", today == now.date())

Converting between timezones

You can use the zoneinfo module to convert between timezones:

Create the datetime
Attach the timezone that it represents
Use the astimezone in combination with the ZoneInfo method to convert to the new datetime of the new timezone

Example:

from datetime import datetime, timezone

from zoneinfo import ZoneInfo

# Create a datetime object, will use UTC as an example

utc_dt = datetime(2025, 9, 15, 12, 0, 0)

# Attach the timezone

utc_dt = utc_dt.replace(tzinfo=timezone.utc)

print("Stored in UTC:", utc_dt)

# Convert UTC to London time

london_dt = utc_dt.astimezone(ZoneInfo("Europe/London"))

print("London:", london_dt)

# Convert UTC to New York time