如果a, b是datetime对象，那么在Python 3中查找它们之间的时间差:

from datetime import timedelta

time_difference = a - b
time_difference_in_minutes = time_difference / timedelta(minutes=1)

在早期的Python版本中:

time_difference_in_minutes = time_difference.total_seconds() / 60

如果a, b是天真的datetime对象，例如datetime.now()返回的，那么如果对象表示具有不同UTC偏移量的本地时间，例如DST转换前后或过去/未来日期，则结果可能是错误的。更多细节:查找datetimes之间是否已经过了24小时- Python。

要获得可靠的结果，请使用UTC时间或时区感知的datetime对象。

以datetime为例

>>> from datetime import datetime
>>> then = datetime(2012, 3, 5, 23, 8, 15)        # Random date in the past
>>> now  = datetime.now()                         # Now
>>> duration = now - then                         # For build-in functions
>>> duration_in_s = duration.total_seconds()      # Total number of seconds between dates

持续时间(年)

>>> years = divmod(duration_in_s, 31536000)[0]    # Seconds in a year=365*24*60*60 = 31536000.

持续时间(天)

>>> days  = duration.days                         # Build-in datetime function
>>> days  = divmod(duration_in_s, 86400)[0]       # Seconds in a day = 86400

持续时间(小时)

>>> hours = divmod(duration_in_s, 3600)[0]        # Seconds in an hour = 3600

持续时间(分钟)

>>> minutes = divmod(duration_in_s, 60)[0]        # Seconds in a minute = 60

持续时间(秒)

[!参见本文底部关于使用持续时间以秒为单位的警告

>>> seconds = duration.seconds                    # Build-in datetime function
>>> seconds = duration_in_s

持续时间(微秒)

[!参见本文底部关于使用以微秒为单位的持续时间的警告

>>> microseconds = duration.microseconds          # Build-in datetime function

两个日期之间的总时间

>>> days    = divmod(duration_in_s, 86400)        # Get days (without [0]!)
>>> hours   = divmod(days[1], 3600)               # Use remainder of days to calc hours
>>> minutes = divmod(hours[1], 60)                # Use remainder of hours to calc minutes
>>> seconds = divmod(minutes[1], 1)               # Use remainder of minutes to calc seconds
>>> print("Time between dates: %d days, %d hours, %d minutes and %d seconds" % (days[0], hours[0], minutes[0], seconds[0]))

或者仅仅是:

>>> print(now - then)

---

编辑2019 由于这个答案已经获得了支持，我将添加一个函数，这可能会简化一些用法

from datetime import datetime

def getDuration(then, now = datetime.now(), interval = "default"):

    # Returns a duration as specified by variable interval
    # Functions, except totalDuration, returns [quotient, remainder]

    duration = now - then # For build-in functions
    duration_in_s = duration.total_seconds() 
    
    def years():
      return divmod(duration_in_s, 31536000) # Seconds in a year=31536000.

    def days(seconds = None):
      return divmod(seconds if seconds != None else duration_in_s, 86400) # Seconds in a day = 86400

    def hours(seconds = None):
      return divmod(seconds if seconds != None else duration_in_s, 3600) # Seconds in an hour = 3600

    def minutes(seconds = None):
      return divmod(seconds if seconds != None else duration_in_s, 60) # Seconds in a minute = 60

    def seconds(seconds = None):
      if seconds != None:
        return divmod(seconds, 1)   
      return duration_in_s

    def totalDuration():
        y = years()
        d = days(y[1]) # Use remainder to calculate next variable
        h = hours(d[1])
        m = minutes(h[1])
        s = seconds(m[1])

        return "Time between dates: {} years, {} days, {} hours, {} minutes and {} seconds".format(int(y[0]), int(d[0]), int(h[0]), int(m[0]), int(s[0]))

    return {
        'years': int(years()[0]),
        'days': int(days()[0]),
        'hours': int(hours()[0]),
        'minutes': int(minutes()[0]),
        'seconds': int(seconds()),
        'default': totalDuration()
    }[interval]

# Example usage
then = datetime(2012, 3, 5, 23, 8, 15)
now = datetime.now()

print(getDuration(then)) # E.g. Time between dates: 7 years, 208 days, 21 hours, 19 minutes and 15 seconds
print(getDuration(then, now, 'years'))      # Prints duration in years
print(getDuration(then, now, 'days'))       #                    days
print(getDuration(then, now, 'hours'))      #                    hours
print(getDuration(then, now, 'minutes'))    #                    minutes
print(getDuration(then, now, 'seconds'))    #                    seconds

警告:关于内置的.seconds和.microseconds的警告 datetime。Seconds和datetime。微秒的上限分别为[0,86400)和[0,10^6)。

如果timedelta大于返回值的最大值，则应该谨慎使用。

例子:

开始后1h, 200μs结束:

>>> start = datetime(2020,12,31,22,0,0,500)
>>> end = datetime(2020,12,31,23,0,0,700)
>>> delta = end - start
>>> delta.microseconds
RESULT: 200
EXPECTED: 3600000200

End在开始后1d和1h:

>>> start = datetime(2020,12,30,22,0,0)
>>> end = datetime(2020,12,31,23,0,0)
>>> delta = end - start
>>> delta.seconds
RESULT: 3600
EXPECTED: 90000

这就是我如何获得两个datetime之间经过的小时数。datetime对象:

before = datetime.datetime.now()
after  = datetime.datetime.now()
hours  = math.floor(((after - before).seconds) / 3600)

Python 2.7新增了timedelta实例方法.total_seconds()。在Python文档中，这相当于(td。微秒+ (td。秒+ td。天* 24 * 3600)* 10**6)/ 10**6。

参考:http://docs.python.org/2/library/datetime.html # datetime.timedelta.total_seconds

>>> import datetime
>>> time1 = datetime.datetime.now()
>>> time2 = datetime.datetime.now() # waited a few minutes before pressing enter
>>> elapsedTime = time2 - time1
>>> elapsedTime
datetime.timedelta(0, 125, 749430)
>>> divmod(elapsedTime.total_seconds(), 60)
(2.0, 5.749430000000004) # divmod returns quotient and remainder
# 2 minutes, 5.74943 seconds

这里有一个很容易概括或转化为函数的答案，它合理紧凑，易于遵循。

ts_start=datetime(2020, 12, 1, 3, 9, 45)
ts_end=datetime.now()
ts_diff=ts_end-ts_start
secs=ts_diff.total_seconds()
days,secs=divmod(secs,secs_per_day:=60*60*24)
hrs,secs=divmod(secs,secs_per_hr:=60*60)
mins,secs=divmod(secs,secs_per_min:=60)
secs=round(secs, 2)
answer='Duration={} days, {} hrs, {} mins and {} secs'.format(int(days),int(hrs),int(mins),secs)
print(answer)

它给出的答案是“持续时间=270天10小时32分42.13秒”

这可能会帮助一些人，用这个方法找到过期与否其计算天数。这是dt。秒和dt。微秒也可用

from datetime import datetime
# updated_at = "2022-10-20T07:18:56.950563"
def is_expired(updated_at):
    expires_in = 7 #days
    datetime_format = '%Y-%m-%dT%H:%M:%S.%f'
    time_difference = datetime.now() - datetime.strptime(updated_at, datetime_format)

    return True if time_difference.days > expires_in else False