There is the no directive mentioned in time.strftime(...) that will return you the milliseconds. Not sure from where you got the reference to use %f. In fact time.gmtime(...) holds the precision only upto seconds.

As a hack, in order to achieve this, you may explicitly format your string by preserving your milli second value as:

>>> import time

>>> time_in_ms = 1515694048121
>>> time.strftime('%Y-%m-%d %H:%M:%S:{}'.format(time_in_ms%1000), time.gmtime(time_in_ms/1000.0))
'2018-01-11 18:07:28:121'

Here's the list of valid directives:

+-----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| Directive |                                                                                                   Meaning                                                                                                   | Notes |
+-----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+
| %a        | Locale’s abbreviated weekday name.                                                                                                                                                                          |       |
| %A        | Locale’s full weekday name.                                                                                                                                                                                 |       |
| %b        | Locale’s abbreviated month name.                                                                                                                                                                            |       |
| %B        | Locale’s full month name.                                                                                                                                                                                   |       |
| %c        | Locale’s appropriate date and time representation.                                                                                                                                                          |       |
| %d        | Day of the month as a decimal number [01,31].                                                                                                                                                               |       |
| %H        | Hour (24-hour clock) as a decimal number [00,23].                                                                                                                                                           |       |
| %I        | Hour (12-hour clock) as a decimal number [01,12].                                                                                                                                                           |       |
| %j        | Day of the year as a decimal number [001,366].                                                                                                                                                              |       |
| %m        | Month as a decimal number [01,12].                                                                                                                                                                          |       |
| %M        | Minute as a decimal number [00,59].                                                                                                                                                                         |       |
| %p        | Locale’s equivalent of either AM or PM.                                                                                                                                                                     | (1)   |
| %S        | Second as a decimal number [00,61].                                                                                                                                                                         | (2)   |
| %U        | Week number of the year (Sunday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Sunday are considered to be in week 0.                                | (3)   |
| %w        | Weekday as a decimal number [0(Sunday),6].                                                                                                                                                                  |       |
| %W        | Week number of the year (Monday as the first day of the week) as a decimal number [00,53]. All days in a new year preceding the first Monday are considered to be in week 0.                                | (3)   |
| %x        | Locale’s appropriate date representation.                                                                                                                                                                   |       |
| %X        | Locale’s appropriate time representation.                                                                                                                                                                   |       |
| %y        | Year without century as a decimal number [00,99].                                                                                                                                                           |       |
| %Y        | Year with century as a decimal number.                                                                                                                                                                      |       |
| %z        | Time zone offset indicating a positive or negative time difference from UTC/GMT of the form +HHMM or -HHMM, where H represents decimal hour digits and M represents decimal minute digits [-23:59, +23:59]. |       |
| %Z        | Time zone name (no characters if no time zone exists).                                                                                                                                                      |       |
| %%        |                                                                                                                                                                                                             |       |
+-----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------+

To get a date string with milliseconds, use [:-3] to trim the last three digits of %f (microseconds):

>>> from datetime import datetime
>>> datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f')[:-3]
'2022-09-24 10:18:32.926'

Or shorter:

>>> from datetime import datetime
>>> datetime.utcnow().strftime('%F %T.%f')[:-3]
'2022-09-24 10:18:32.926'

See the Python docs for more "%" format codes and the strftime(3) man page for the full list.

Python 2.6 added a new strftime/strptime macro %f. The docs are a bit misleading as they only mention microseconds, but %f actually parses any decimal fraction of seconds with up to 6 digits, meaning it also works for milliseconds or even centiseconds or deciseconds.

time.strptime('30/03/09 16:31:32.123', '%d/%m/%y %H:%M:%S.%f')

However, time.struct_time doesn't actually store milliseconds/microseconds. You're better off using datetime, like this:

>>> from datetime import datetime
>>> a = datetime.strptime('30/03/09 16:31:32.123', '%d/%m/%y %H:%M:%S.%f')
>>> a.microsecond
123000

As you can see, .123 is correctly interpreted as 123 000 microseconds.

You can use datetime's strftime() function to get this. The problem is that time's strftime() accepts a timetuple that does not carry microsecond information.

from datetime import datetime
datetime.now().strftime("%H:%M:%S.%f")

Should do the trick!

In Python 3 this can be done in 2 steps:

1. Convert timestring to datetime object
2. Multiply the timestamp of the datetime object by 1000 to convert it to milliseconds.

For example like this:

from datetime import datetime

dt_obj = datetime.strptime('20.12.2016 09:38:42,76',
                           '%d.%m.%Y %H:%M:%S,%f')
millisec = dt_obj.timestamp() * 1000

print(millisec)

Output:

1482223122760.0

strptime accepts your timestring and a format string as input. The timestring (first argument) specifies what you actually want to convert to a datetime object. The format string (second argument) specifies the actual format of the string that you have passed.

Here is the explanation of the format specifiers from the official documentation:

• %d - Day of the month as a zero-padded decimal number.
• %m - Month as a zero-padded decimal number.
• %Y - Year with century as a decimal number
• %H - Hour (24-hour clock) as a zero-padded decimal number.
• %M - Minute as a zero-padded decimal number.
• %S - Second as a zero-padded decimal number.
• %f - Microsecond as a decimal number, zero-padded to 6 digits.