How do I check the difference, in seconds, between two dates?

python

datetime

timestamp

date-string

byAlex Kataev·Oct 21, 2024

Here's a quick way to calculate time differences in Python using the datetime module:

from datetime import datetime

# Example dates
date1 = datetime(2023, 1, 1, 0, 0) 
date2 = datetime(2023, 1, 1, 1, 0) 

# Seconds difference
seconds = (date2 - date1).total_seconds()

print(seconds)  # Let's see, that's 3600.0 seconds, right?

Just subtract date1 from date2 and call .total_seconds() on the result. It's like magic, but with code!

Dealing with Different Durations

For short durations

Need to calculate the difference in seconds for a short duration of time? Use total_seconds(). It's precise and to the point:

# Assuming time1 and time2 are datetime objects  
time_diff = time2 - time1 # Make way for Pythogoras here
seconds = time_diff.total_seconds()

For longer durations

As time advances, so does our quest for capturing longer durations. Still, total_seconds() gets the job done:

# Days attribute could be your secret sauce here
long_duration = datetime(2023, 1, 1) - datetime(2022, 1, 1) # Hello to a year-long journey
total_seconds = long_duration.total_seconds()

Here, total_seconds coverts all moments, from days to hours, into no-nonsense seconds.

The lighter timers

For those eager to shed some bytes, use time.time() for direct timestamp access:

import time

time_start = time.time() # The clock starts ticking
# ...maybe pause here to admire the view...
time_end = time.time() # And...it's a wrap!

elapsed_time_in_seconds = time_end - time_start # Who needs a stopwatch?

Refresh and Expiry Calculations

Business use-cases often require calculations of object refresh or expiry times.

Refresh time check

To check if an object needs refreshing:

from datetime import datetime, timedelta

create_time = datetime.now() # Born now, refresh later
expires_after = timedelta(hours=1)  # Your friendly expiry timer set for 1 hour

# Check if it's time for a refresh
def needs_refresh(create_time, threshold):
    return datetime.now() - create_time > threshold

print(needs_refresh(create_time, expires_after))  # True or False, depending on what time tells us

Expiry time calculation

Do the math to check when it's time to let go:

expiration_time = create_time + expires_after # Parting time calculated
if datetime.now() >= expiration_time:
    # Maybe, time to say goodbye

Dealing with Date Strings

Life might throw dates as strings at you. Fret not, convert these string dates into datetime objects warm enough to compute:

from datetime import datetime

date_str1 = "2023-01-01 10:00:00"  # A time, frozen in a string
date_str2 = "2023-01-01 11:00:00"  # Yet another moment captured 

format = "%Y-%m-%d %H:%M:%S"  # Yes, every format matters
date1 = datetime.strptime(date_str1, format) # From stringhood to datetimehood
date2 = datetime.strptime(date_str2, format)

# Get those seconds
seconds = (date2 - date1).total_seconds() # Voila!

Version Matters: Pre Python 2.7

Pythonistas using Python < 2.7, don't lose heart, use mktime() with strptime() like so:

from time import mktime, strptime

time_tuple1 = strptime(date_str1, format)
time_tuple2 = strptime(date_str2, format)

seconds = mktime(time_tuple2) - mktime(time_tuple1) # Calculating seconds in style