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Does Python's time.time() return the local or UTC timestamp?


Question

Does time.time() in the Python time module return the system's time or the time in UTC?

2015/12/05
1
574
12/5/2015 3:59:36 PM

Accepted Answer

The time.time() function returns the number of seconds since the epoch, as seconds. Note that the "epoch" is defined as the start of January 1st, 1970 in UTC. So the epoch is defined in terms of UTC and establishes a global moment in time. No matter where you are "seconds past epoch" (time.time()) returns the same value at the same moment.

Here is some sample output I ran on my computer, converting it to a string as well.

Python 2.7.3 (default, Apr 24 2012, 00:00:54) 
[GCC 4.7.0 20120414 (prerelease)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import time
>>> ts = time.time()
>>> print ts
1355563265.81
>>> import datetime
>>> st = datetime.datetime.fromtimestamp(ts).strftime('%Y-%m-%d %H:%M:%S')
>>> print st
2012-12-15 01:21:05
>>>

The ts variable is the time returned in seconds. I then converted it to a string using the datetime library making it a string that is human readable.

2017/10/23
802
10/23/2017 4:52:07 PM


Based on the answer from #squiguy, to get a true timestamp I would type cast it from float.

>>> import time
>>> ts = int(time.time())
>>> print(ts)
1389177318

At least that's the concept.

2014/01/08

The answer could be neither or both.

  • neither: time.time() returns approximately the number of seconds elapsed since the Epoch. The result doesn't depend on timezone so it is neither UTC nor local time. Here's POSIX defintion for "Seconds Since the Epoch".

  • both: time.time() doesn't require your system's clock to be synchronized so it reflects its value (though it has nothing to do with local timezone). Different computers may get different results at the same time. On the other hand if your computer time is synchronized then it is easy to get UTC time from the timestamp (if we ignore leap seconds):

    from datetime import datetime
    
    utc_dt = datetime.utcfromtimestamp(timestamp)
    

On how to get timestamps from UTC time in various Python versions, see How can I get a date converted to seconds since epoch according to UTC?

2017/05/23

I eventually settled for:

>>> import time
>>> time.mktime(time.gmtime())
1509467455.0
2017/10/31

There is no such thing as an "epoch" in a specific timezone. The epoch is well-defined as a specific moment in time, so if you change the timezone, the time itself changes as well. Specifically, this time is Jan 1 1970 00:00:00 UTC. So time.time() returns the number of seconds since the epoch.

2016/08/20

timestamp is always time in utc, but when you call datetime.datetime.fromtimestamp it returns you time in your local timezone corresponding to this timestamp, so result depend of your locale.

>>> import time, datetime

>>> time.time()
1564494136.0434234

>>> datetime.datetime.now()
datetime.datetime(2019, 7, 30, 16, 42, 3, 899179)
>>> datetime.datetime.fromtimestamp(time.time())
datetime.datetime(2019, 7, 30, 16, 43, 12, 4610)

There exist nice library arrow with different behaviour. In same case it returns you time object with UTC timezone.

>>> import arrow
>>> arrow.now()
<Arrow [2019-07-30T16:43:27.868760+03:00]>
>>> arrow.get(time.time())
<Arrow [2019-07-30T13:43:56.565342+00:00]>