This document describes the current stable version of Celery (5.4). For development docs, go here.


Utilities related to dates, times, intervals, and timezones.

class celery.utils.time.LocalTimezone[source]

Local time implementation. Provided in _Zone to the app when enable_utc is disabled. Otherwise, _Zone provides a UTC ZoneInfo instance as the timezone implementation for the application.


Used only when the enable_utc setting is disabled.

dst(dt: datetime) timedelta[source]

datetime -> DST offset as timedelta positive east of UTC.

fromutc(dt: datetime) datetime[source]

datetime in UTC -> datetime in local time.

tzname(dt: datetime) str[source]

datetime -> string name of time zone.

utcoffset(dt: datetime) timedelta[source]

datetime -> timedelta showing offset from UTC, negative values indicating West of UTC

celery.utils.time.adjust_timestamp(ts: float, offset: int, here: ~typing.Callable[[...], float] = <function utcoffset>) float[source]

Adjust timestamp based on provided utcoffset.

celery.utils.time.delta_resolution(dt: datetime, delta: timedelta) datetime[source]

Round a datetime to the resolution of timedelta.

If the timedelta is in days, the datetime will be rounded to the nearest days, if the timedelta is in hours the datetime will be rounded to the nearest hour, and so on until seconds, which will just return the original datetime.

class celery.utils.time.ffwd(year=None, month=None, weeks=0, weekday=None, day=None, hour=None, minute=None, second=None, microsecond=None, **kwargs: Any)[source]

Version of dateutil.relativedelta that only supports addition.

celery.utils.time.get_exponential_backoff_interval(factor: int, retries: int, maximum: int, full_jitter: bool = False) int[source]

Calculate the exponential backoff wait time.

celery.utils.time.humanize_seconds(secs: int, prefix: str = '', sep: str = '', now: str = 'now', microseconds: bool = False) str[source]

Show seconds in human form.

For example, 60 becomes “1 minute”, and 7200 becomes “2 hours”.

  • prefix (str) – can be used to add a preposition to the output (e.g., ‘in’ will give ‘in 1 second’, but add nothing to ‘now’).

  • now (str) – Literal ‘now’.

  • microseconds (bool) – Include microseconds.

celery.utils.time.is_naive(dt: datetime) bool[source]

Return True if datetime is naive, meaning it doesn’t have timezone info set.

celery.utils.time.localize(dt: datetime, tz: tzinfo) datetime[source]

Convert aware datetime to another timezone.

Using a ZoneInfo timezone will give the most flexibility in terms of ambiguous DST handling.

celery.utils.time.make_aware(dt: datetime, tz: tzinfo) datetime[source]

Set timezone for a datetime object.

celery.utils.time.maybe_iso8601(dt: datetime | str | None) None | datetime[source]

Either datetime | str -> datetime or None -> None.

celery.utils.time.maybe_make_aware(dt: datetime, tz: tzinfo | None = None, naive_as_utc: bool = True) datetime[source]

Convert dt to aware datetime, do nothing if dt is already aware.

celery.utils.time.maybe_timedelta(delta: int) timedelta[source]

Convert integer to timedelta, if argument is an integer.

celery.utils.time.rate(r: str) float[source]

Convert rate string (“100/m”, “2/h” or “0.5/s”) to seconds.

celery.utils.time.remaining(start: datetime, ends_in: timedelta, now: Callable | None = None, relative: bool = False) timedelta[source]

Calculate the remaining time for a start date and a timedelta.

For example, “how many seconds left for 30 seconds after start?”

  • start (datetime) – Starting date.

  • ends_in (timedelta) – The end delta.

  • relative (bool) – If enabled the end time will be calculated using delta_resolution() (i.e., rounded to the resolution of ends_in).

  • now (Callable) – Function returning the current time and date. Defaults to


Remaining time.

Return type:


celery.utils.time.to_utc(dt: datetime) datetime[source]

Convert naive datetime to UTC.

celery.utils.time.utcoffset(time: ~types.ModuleType = <module 'time' (built-in)>, localtime: ~typing.Callable[[...], ~time.struct_time] = <built-in function localtime>) float[source]

Return the current offset to UTC in hours.

celery.utils.time.weekday(name: str) int[source]

Return the position of a weekday: 0 - 7, where 0 is Sunday.


>>> weekday('sunday'), weekday('sun'), weekday('mon')
(0, 0, 1)