`time` — Time access and conversions¶

This module provides various time-related functions. For related functionality, see also the datetime and calendar modules.

Although this module is always available, not all functions are available on all platforms. Most of the functions defined in this module call platform C library functions with the same name. It may sometimes be helpful to consult the platform documentation, because the semantics of these functions varies among platforms.

An explanation of some terminology and conventions is in order.

The epoch is the point where the time starts, the return value of time.gmtime(0). It is January 1, 1970, 00:00:00 (UTC) on all platforms.

The term seconds since the epoch refers to the total number of elapsed seconds since the epoch, typically excluding leap seconds. Leap seconds are excluded from this total on all POSIX-compliant platforms.

The functions in this module may not handle dates and times before the epoch or far in the future. The cut-off point in the future is determined by the C library; for 32-bit systems, it is typically in 2038.

Function strptime() can parse 2-digit years when given %y format code. When 2-digit years are parsed, they are converted according to the POSIX and ISO C standards: values 69–99 are mapped to 1969–1999, and values 0–68 are mapped to 2000–2068.

UTC is Coordinated Universal Time and superseded Greenwich Mean Time or GMT as the basis of international timekeeping. The acronym UTC is not a mistake but conforms to an earlier, language-agnostic naming scheme for time standards such as UT0, UT1, and UT2.

DST is Daylight Saving Time, an adjustment of the timezone by (usually) one hour during part of the year. DST rules are magic (determined by local law) and can change from year to year. The C library has a table containing the local rules (often it is read from a system file for flexibility) and is the only source of True Wisdom in this respect.
The precision of the various real-time functions may be less than suggested by the units in which their value or argument is expressed. E.g. on most Unix systems, the clock “ticks” only 50 or 100 times a second.
On the other hand, the precision of time() and sleep() is better than their Unix equivalents: times are expressed as floating-point numbers, time() returns the most accurate time available (using Unix gettimeofday() where available), and sleep() will accept a time with a nonzero fraction (Unix select() is used to implement this, where available).
The time value as returned by gmtime(), localtime(), and strptime(), and accepted by asctime(), mktime() and strftime(), is a sequence of 9 integers. The return values of gmtime(), localtime(), and strptime() also offer attribute names for individual fields.

See struct_time for a description of these objects.

Changed in version 3.3: The struct_time type was extended to provide the tm_gmtoff and tm_zone attributes when platform supports corresponding struct tm members.

Changed in version 3.6: The struct_time attributes tm_gmtoff and tm_zone are now available on all platforms.

Use the following functions to convert between time representations:

From	To	Use
seconds since the epoch	`struct_time` in UTC	`gmtime()`
seconds since the epoch	`struct_time` in local time	`localtime()`
`struct_time` in UTC	seconds since the epoch	`calendar.timegm()`
`struct_time` in local time	seconds since the epoch	`mktime()`

Functions¶

time.asctime([time_tuple])¶

Convert a tuple or struct_time representing a time as returned by gmtime() or localtime() to a string of the following form: 'Sun Jun 20 23:21:05 1993'. The day field is two characters long and is space padded if the day is a single digit, for example: 'Wed Jun 9 04:26:40 1993'.

If time_tuple is not provided, the current time as returned by localtime() is used. Locale information is not used by asctime().

Note

Unlike the C function of the same name, asctime() does not add a trailing newline.

time.pthread_getcpuclockid(thread_id, /)¶

Return the clk_id of the thread-specific CPU-time clock for the specified thread_id.

Use threading.get_ident() or the ident attribute of threading.Thread objects to get a suitable value for thread_id.

Warning

Passing an invalid or expired thread_id may result in undefined behavior, such as segmentation fault.

Availability: Unix

See the man page for pthread_getcpuclockid(3) for further information.

Added in version 3.7.

time.clock_getres(clk_id, /)¶: Return the resolution (precision) of the specified clock clk_id. Refer to Clock ID Constants for a list of accepted values for clk_id.

Availability: Unix.

Added in version 3.3.

time.clock_gettime(clk_id, /) → float¶

Return the time of the specified clock clk_id. Refer to Clock ID Constants for a list of accepted values for clk_id.

Use clock_gettime_ns() to avoid the precision loss caused by the float type.

Availability: Unix.

Added in version 3.3.

time.clock_gettime_ns(clk_id, /) → int¶: Similar to clock_gettime() but return time as nanoseconds.

Availability: Unix.

Added in version 3.7.

time.clock_settime(clk_id, time, /)¶

Set the time of the specified clock clk_id. Currently, CLOCK_REALTIME is the only accepted value for clk_id.

Use clock_settime_ns() to avoid the precision loss caused by the float type.

Availability: Unix, not Android, not iOS.

Added in version 3.3.

Changed in version 3.15: Accepts any real number as time, not only integer or float.

time.clock_settime_ns(clk_id, time: int, /)¶: Similar to clock_settime() but set time with nanoseconds.

Availability: Unix, not Android, not iOS.

Added in version 3.7.

time.ctime(seconds=None, /)¶

Convert a time expressed in seconds since the epoch to a string of a form: 'Sun Jun 20 23:21:05 1993' representing local time. The day field is two characters long and is space padded if the day is a single digit, for example: 'Wed Jun 9 04:26:40 1993'.

If seconds is not provided or None, the current time as returned by time() is used. ctime(seconds) is equivalent to asctime(localtime(seconds)). Locale information is not used by ctime().

Changed in version 3.15: Accepts any real number, not only integer or float.

time.get_clock_info(name, /)¶

Get information on the specified clock as a namespace object. Supported clock names and the corresponding functions to read their value are:

'monotonic': time.monotonic()
'perf_counter': time.perf_counter()
'process_time': time.process_time()
'thread_time': time.thread_time()
'time': time.time()

The result has the following attributes:

adjustable: True if the clock can be set to jump forward or backward in time, False otherwise. Does not refer to gradual NTP rate adjustments.
implementation: The name of the underlying C function used to get the clock value. Refer to Clock ID Constants for possible values.
monotonic: True if the clock cannot go backward, False otherwise
resolution: The resolution of the clock in seconds (float)

Added in version 3.3.

time.gmtime(seconds=None, /)¶: Convert a time expressed in seconds since the epoch to a struct_time in UTC in which the dst flag is always zero. If seconds is not provided or None, the current time as returned by time() is used. Fractions of a second are ignored. See above for a description of the struct_time object. See calendar.timegm() for the inverse of this function.

Changed in version 3.15: Accepts any real number, not only integer or float.

time.localtime(seconds=None, /)¶

Like gmtime() but converts to local time. If seconds is not provided or None, the current time as returned by time() is used. The dst flag is set to 1 when DST applies to the given time.

localtime() may raise OverflowError, if the timestamp is outside the range of values supported by the platform C localtime() or gmtime() functions, and OSError on localtime() or gmtime() failure. It’s common for this to be restricted to years between 1970 and 2038.

Changed in version 3.15: Accepts any real number, not only integer or float.

time.mktime(time_tuple, /)¶: This is the inverse function of localtime(). Its argument is the struct_time or full 9-tuple (since the dst flag is needed; use -1 as the dst flag if it is unknown) which expresses the time in local time, not UTC. It returns a floating-point number, for compatibility with time(). If the input value cannot be represented as a valid time, either OverflowError or ValueError will be raised (which depends on whether the invalid value is caught by Python or the underlying C libraries). The earliest date for which it can generate a time is platform-dependent.

time.monotonic() → float¶

Return the value (in fractional seconds) of a monotonic clock, i.e. a clock that cannot go backwards. The clock is not affected by system clock updates. The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.

Clock:

On Windows, call QueryPerformanceCounter() and QueryPerformanceFrequency().
On macOS, call mach_absolute_time() and mach_timebase_info().
On HP-UX, call gethrtime().
Call clock_gettime(CLOCK_HIGHRES) if available.
Otherwise, call clock_gettime(CLOCK_MONOTONIC).

Use monotonic_ns() to avoid the precision loss caused by the float type.

Added in version 3.3.

Changed in version 3.5: The function is now always available and the clock is now the same for all processes.

Changed in version 3.10: On macOS, the clock is now the same for all processes.

time.monotonic_ns() → int¶: Similar to monotonic(), but return time as nanoseconds.

Added in version 3.7.

time.perf_counter() → float¶

Return the value (in fractional seconds) of a performance counter, i.e. a clock with the highest available resolution to measure a short duration. It does include time elapsed during sleep. The clock is the same for all processes. The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.

CPython implementation detail: On CPython, use the same clock as time.monotonic() and is a monotonic clock, i.e. a clock that cannot go backwards.

Use perf_counter_ns() to avoid the precision loss caused by the float type.

Added in version 3.3.

Changed in version 3.10: On Windows, the clock is now the same for all processes.

Changed in version 3.13: Use the same clock as time.monotonic().

time.perf_counter_ns() → int¶: Similar to perf_counter(), but return time as nanoseconds.

Added in version 3.7.

time.process_time() → float¶

Return the value (in fractional seconds) of the sum of the system and user CPU time of the current process. It does not include time elapsed during sleep. It is process-wide by definition. The reference point of the returned value is undefined, so that only the difference between the results of two calls is valid.

Use process_time_ns() to avoid the precision loss caused by the float type.

Added in version 3.3.

time.process_time_ns() → int¶: Similar to process_time() but return time as nanoseconds.

Added in version 3.7.

time.sleep(seconds, /)¶

Suspend execution of the calling thread for the given number of seconds. The argument may be a non-integer to indicate a more precise sleep time.

If the sleep is interrupted by a signal and no exception is raised by the signal handler, the sleep is restarted with a recomputed timeout.

The suspension time may be longer than requested by an arbitrary amount, because of the scheduling of other activity in the system.

Windows implementation

On Windows, if seconds is zero, the thread relinquishes the remainder of its time slice to any other thread that is ready to run. If there are no other threads ready to run, the function returns immediately, and the thread continues execution. On Windows 10 and newer the implementation uses a high-resolution timer which provides resolution of 100 nanoseconds. If seconds is zero, Sleep(0) is used.

Unix implementation

Use clock_nanosleep() if available (resolution: 1 nanosecond);
Or use nanosleep() if available (resolution: 1 nanosecond);
Or use select() (resolution: 1 microsecond).

Note

To emulate a “no-op”, use pass instead of time.sleep(0).

To voluntarily relinquish the CPU, specify a real-time scheduling policy and use os.sched_yield() instead.

Raises an auditing event time.sleep with argument seconds.

Changed in version 3.5: The function now sleeps at least seconds even if the sleep is interrupted by a signal, except if the signal handler raises an exception (see PEP 475 for the rationale).

Changed in version 3.11: On Unix, the clock_nanosleep() and nanosleep() functions are now used if available. On Windows, a waitable timer is now used.

Changed in version 3.13: Raises an auditing event.

Changed in version 3.15: Accepts any real number, not only integer or float.

time.strftime(format[, time_tuple])¶

Convert a tuple or struct_time representing a time as returned by gmtime() or localtime() to a string as specified by the format argument. If time_tuple is not provided, the current time as returned by localtime() is used. format must be a string. ValueError is raised if any field in time_tuple is outside of the allowed range.

0 is a legal argument for any position in the time tuple; if it is normally illegal the value is forced to a correct one.

The following directives can be embedded in the format string. They are shown without the optional field width and precision specification, and are replaced by the indicated characters in the strftime() result:

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].
`%f`	Microseconds as a decimal number [000000,999999].	(1)
`%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.	(2)
`%S`	Second as a decimal number [00,61].	(3)
`%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.	(4)
`%u`	Day of the week (Monday is 1; Sunday is 7) as a decimal number [1, 7].
`%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.	(4)
`%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]. [1]
`%Z`	Time zone name (no characters if no time zone exists). Deprecated. [1]
`%G`	ISO 8601 year (similar to `%Y` but follows the rules for the ISO 8601 calendar year). The year starts with the week that contains the first Thursday of the calendar year.
`%V`	ISO 8601 week number (as a decimal number [01,53]). The first week of the year is the one that contains the first Thursday of the year. Weeks start on Monday.
`%%`	A literal `'%'` character.

Notes:

The %f format directive only applies to strptime(), not to strftime(). However, see also datetime.datetime.strptime() and datetime.datetime.strftime() where the %f format directive applies to microseconds.
When used with the strptime() function, the %p directive only affects the output hour field if the %I directive is used to parse the hour.

The range really is 0 to 61; value 60 is valid in timestamps representing leap seconds and value 61 is supported for historical reasons.
When used with the strptime() function, %U and %W are only used in calculations when the day of the week and the year are specified.

Here is an example, a format for dates compatible with that specified in the RFC 5322 Internet email standard. [1]

>>> from time import gmtime, strftime
>>> strftime("%a, %d %b %Y %H:%M:%S +0000", gmtime())
'Thu, 28 Jun 2001 14:17:15 +0000'

Additional directives may be supported on certain platforms, but only the ones listed here have a meaning standardized by ANSI C. To see the full set of format codes supported on your platform, consult the strftime(3) documentation.

On some platforms, an optional field width and precision specification can immediately follow the initial '%' of a directive in the following order; this is also not portable. The field width is normally 2 except for %j where it is 3.

time.strptime(string[, format])¶

Parse a string representing a time according to a format. The return value is a struct_time as returned by gmtime() or localtime().

The format parameter uses the same directives as those used by strftime(); it defaults to "%a %b %d %H:%M:%S %Y" which matches the formatting returned by ctime(). If string cannot be parsed according to format, or if it has excess data after parsing, ValueError is raised. The default values used to fill in any missing data when more accurate values cannot be inferred are (1900, 1, 1, 0, 0, 0, 0, 1, -1). Both string and format must be strings.

For example:

>>> import time
>>> time.strptime("30 Nov 00", "%d %b %y")
time.struct_time(tm_year=2000, tm_mon=11, tm_mday=30, tm_hour=0, tm_min=0,
                 tm_sec=0, tm_wday=3, tm_yday=335, tm_isdst=-1)

Support for the %Z directive is based on the values contained in tzname and whether daylight is true. Because of this, it is platform-specific except for recognizing UTC and GMT which are always known (and are considered to be non-daylight savings timezones).

Only the directives specified in the documentation are supported. Because strftime() is implemented per platform it can sometimes offer more directives than those listed. But strptime() is independent of any platform and thus does not necessarily support all directives available that are not documented as supported.

class time.struct_time¶

The type of the time value sequence returned by gmtime(), localtime(), and strptime(). It is an object with a named tuple interface: values can be accessed by index and by attribute name. The following values are present:

Index	Attribute	Values
0	tm_year¶	(for example, 1993)
1	tm_mon¶	range [1, 12]
2	tm_mday¶	range [1, 31]
3	tm_hour¶	range [0, 23]
4	tm_min¶	range [0, 59]
5	tm_sec¶	range [0, 61]; see Note (3) in `strftime()`
6	tm_wday¶	range [0, 6]; Monday is 0
7	tm_yday¶	range [1, 366]
8	tm_isdst¶	0, 1 or -1; see below
N/A	tm_zone¶	abbreviation of timezone name
N/A

time — Time access and conversions¶

Functions¶

`time` — Time access and conversions¶