Python3 Get epoch time first and last day of month

Question

Given a month and a year, such as 03 2022, I need to get the epoch time of the first day of the month and the last day of the month. I am not sure how to do that. Any help would be appreciated. Thank you.

Answer 1

Note: see @segaps answer below; my original answer had a floor division by 12 instead of 13 in (dt.month + 1) // 13, which gives incorrect result for the month of November.

• you can get the beginning of the month easily by setting the day to 1
• to get the end of the month, you can calculate the first day of the next month, then go back one day (or whatever duration you need)
• then set the time zone (tzinfo) to UTC to prevent Python using local time
• finally a call to .timestamp() to get Unix time¹

import datetime

def date_to_endofmonth(
    dt: datetime.datetime, offset: datetime.timedelta = datetime.timedelta(days=1)
) -> datetime.datetime:
    """
    Roll a datetime to the end of the month.

    Parameters
    ----------
    dt : datetime.datetime
        datetime object to use.
    offset : datetime.timedelta, optional.
        Offset to the next month. The default is 1 day; datetime.timedelta(days=1).

    Returns
    -------
    datetime.datetime
        End of month datetime.
    """
    # reset day to first day of month, add one month and subtract offset duration
    return (
        datetime.datetime(
            dt.year + ((dt.month + 1) // 13), ((dt.month + 1) % 12) or 12, 1
        )
        - offset
    )

year, month = 2022, 11

# make datetime objects; make sure to set UTC
dt_month_begin = datetime.datetime(year, month, 1, tzinfo=datetime.timezone.utc)
dt_month_end = date_to_endofmonth(dt_month_begin).replace(tzinfo=datetime.timezone.utc)

ts_month_begin = dt_month_begin.timestamp()
ts_month_end = dt_month_end.timestamp()

print(ts_month_begin, ts_month_end)
# 1667260800.0 1669766400.0
print(datetime.datetime.fromtimestamp(ts_month_begin, tz=datetime.timezone.utc), 
      datetime.datetime.fromtimestamp(ts_month_end, tz=datetime.timezone.utc))
# 2022-11-01 00:00:00+00:00 2022-11-30 00:00:00+00:00

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¹ Note that Unix time always represents a date with a time, not only a date.