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Convert datetime from PDT to UTC in python

I have an object of <class 'datetime.datetime'>.
obj = datetime.datetime(2021, 6, 28, 2, 15, tzinfo=<FixedOffset '-07:00'>)
The time zone is PDT(offset -7:00). I need to convert it to UTC.
So if the object has datetime as 2021-05-02 10:00:00.000 -07:00.
It should be changed to 2021-05-02 17:00:00.000 +00:00.
How to achieve this in python?

Try the following, using .astimezone():
>>> import datetime
>>> obj = datetime.datetime.now()
>>> obj
datetime.datetime(2021, 7, 19, 13, 18, 26, 601212)
>>> obj.astimezone(tz=datetime.timezone.utc)
datetime.datetime(2021, 7, 19, 17, 18, 26, 601212, tzinfo=datetime.timezone.utc)

use time delta
bj = dt.datetime(2021,6,28,10,0)+dt.timedelta(hours=7)
pd.to_datetime(bj)

Datetime print time without offset

I am currently trying to convert times from UTC and the problem that i am having is that the offsets seem to be backwards. As you can see when i convert the UTC to EST, it shows an offset of -4:56 yet when i print the time, it seems to add 4:56 as opposed to the way it should be. I would really like to be able to convert a UTC time to any other timezone and have it display the local time there without the offset so the UTC here would be converted to something along the lines of 2019-03-06 9:12 EST.
>>> example.created
datetime.datetime(2019, 3, 6, 14, 8, 49, 841881, tzinfo=<UTC>)
>>> original_utc = example.created
>>> original_utc
datetime.datetime(2019, 3, 6, 14, 8, 49, 841881, tzinfo=<UTC>)
>>> conv_est = original_utc.replace(tzinfo=pytz.timezone('US/Eastern'))
>>> conv_est
datetime.datetime(2019, 3, 6, 14, 8, 49, 841881, tzinfo=<DstTzInfo 'US/Eastern' LMT-1 day, 19:04:00 STD>)
>>> print(conv_est)
2019-03-06 14:08:49.841881-04:56
>>> print(conv_est.astimezone())
2019-03-06 19:04:49.841881+00:00

I suspect that you misunderstood the method .astimezone().
Your original datetime is in UTC
>>> example.created
datetime.datetime(2019, 3, 6, 14, 8, 49, 841881, tzinfo=<UTC>)
Then you changed the timezone info for the variable conv_est, and indeed it works as designed:
>>> conv_est = original_utc.replace(tzinfo=pytz.timezone('US/Eastern'))
>>> conv_est
datetime.datetime(2019, 3, 6, 14, 8, 49, 841881, tzinfo=<DstTzInfo 'US/Eastern' LMT-1 day, 19:04:00 STD>)
If you print this variable, it shows the correct info
>>> print(conv_est)
2019-03-06 14:08:49.841881-04:56
But when you call .astimezone() without any argument, then the return value is a datetime object in UTC zone; that means the method is also working as designed, returning the same point in time but expressed as localtime in UTC (It will be 7PM/19hs in UTC when it is 2PM/14hs in US/Eastern).
>>> print(conv_est.astimezone())
2019-03-06 19:04:49.841881+00:00
You can test that yourself by calculating the difference (which will be 0):
>>> conv_est == conv_est.astimezone()
True
>>> conv_est - conv_est.astimezone()
datetime.timedelta(0)

What is the best way to handle datetime value overflow

I am attempting to build a program to handle alerts. I want it to be able to handle specific dates like 8/23/2015 7:00 and relative dates like 5 days and 7 hours from now. specific dates are fine but for relative dates if I try and just add 5 days and 7 hours to the date time it can overflow the values intended for that spot
import datetime
dt = datetime.datetime.now()
dayslater = 5
hourslater = 7
minuteslater = 30
alarmTime = datetime.datetime(dt.year, dt.month, dt.day + dayslater,
dt.hour + hourslater,
dt.minute + minuteslater, 0,0)
this is fine sometimes but if dayslater was 40 days it would overflow the value. I did set up a simple
if hours >= 24:
hours -= 24
days++
however this won't work for overflowing months whose length in days isn't consistent.

Don't. Dates are hard, and it's very easy to get it wrong.
Instead, use timedelta:
In [1]: from datetime import datetime, timedelta
In [2]: dt = datetime.now()
In [3]: dt
Out[3]: datetime.datetime(2015, 7, 23, 15, 2, 55, 836914)
In [4]: alarmTime = dt + timedelta(days=5, hours=7, minutes=30)
In [5]: alarmTime
Out[5]: datetime.datetime(2015, 7, 28, 22, 32, 55, 836914)

Use a datetime.timedelta() object and leave calculations to the datetime library:
import datetime
delta = datetime.timedelta(days=dayslater, hours=hourslater, minutes=minuteslater)
alarmTime = datetime.datetime.now() + delta
Demo:
>>> import datetime
>>> dt = datetime.datetime.now()
>>> dayslater = 5
>>> hourslater = 7
>>> minuteslater = 30
>>> delta = datetime.timedelta(days=dayslater, hours=hourslater, minutes=minuteslater)
>>> delta
datetime.timedelta(5, 27000)
>>> dt
datetime.datetime(2015, 7, 23, 21, 4, 59, 987926)
>>> dt + delta
datetime.datetime(2015, 7, 29, 4, 34, 59, 987926)
Note how the hours carried over to the next day (from 21:04 to 04:34), and thus the date went from the 23rd to the 29th. I did not have to worry about 'overflow' here.
This continues to work at month boundaries, at year boundaries, and in leap years, with February 29th:
>>> datetime.datetime(2015, 7, 26, 22, 42) + delta
datetime.datetime(2015, 8, 1, 6, 12)
>>> datetime.datetime(2015, 12, 26, 22, 42) + delta
datetime.datetime(2016, 1, 1, 6, 12)
>>> datetime.datetime(2016, 2, 23, 22, 42) + delta
datetime.datetime(2016, 2, 29, 6, 12)

timezone conversion in Python

I'm probably missing something about timezones:
>>> import datetime, pytz
>>> date = datetime.datetime(2013,9,3,16,0, tzinfo=pytz.timezone("Europe/Paris"))
>>> date.astimezone(pytz.UTC)
datetime.datetime(2013, 9, 3, 15, 51, tzinfo=<UTC>)
I was expecting
datetime.datetime(2013, 9, 3, 15, 00, tzinfo=<UTC>)
Can anyone explain me where these 51 minutes come from?
Thanks,
Jean-Philippe

The UTC offset gives (date.tzinfo.utcoffset(date)):
datetime.timedelta(0, 540)
This is 540 seconds or 9 minutes.
In France the switch to UTC was made on March 11, 1911 and the clocks were turned back 9 minutes and 21 seconds (source 1, source 2):
Until 1911, Paris was 9 minutes and 21 seconds off UTC.
You can also see it here (Paris time in 1911) where the time goes from March 11, 12:01:00 AM to March 10, 11:51:39 PM.

Read the note at the very begining of pytz documentation ; use .localize() method to create timezone-aware datetime object:
import datetime
import pytz
naive_dt = datetime.datetime(2013,9,3,16,0)
dt = pytz.timezone("Europe/Paris").localize(naive_dt, is_dst=None)
to_s = lambda d: d.strftime('%Y-%m-%d %H:%M:%S %Z%z')
print(to_s(dt))
print(to_s(dt.astimezone(pytz.utc)))
Output
2013-09-03 16:00:00 CEST+0200
2013-09-03 14:00:00 UTC+0000
I don't know why you are expecting 15:00 UTC here.

Thanks Simeon for your answer. It made me realize how shallow is my understanding of all of this. The following experimentations lost me a little more...
>>> import datetime, pytz
>>> date_paris = datetime.datetime(2013,9,3,16,0, tzinfo=pytz.timezone("Europe/Paris"))
>>> date_utc = datetime.datetime(2013,9,3,16,0, tzinfo=pytz.utc)
>>> date_paris.astimezone(pytz.utc)
datetime.datetime(2013, 9, 3, 15, 51, tzinfo=<UTC>)
>>> date_utc.astimezone(pytz.timezone("Europe/Paris"))
datetime.datetime(2013, 9, 3, 18, 0, tzinfo=<DstTzInfo 'Europe/Paris' CEST+2:00:00 DST>)
Why this 9 minutes offset shows up when converting in one direction but not the other? The following piece of code concentrate all disappointment:
>>> date_paris
datetime.datetime(2013, 9, 3, 16, 0, tzinfo=<DstTzInfo 'Europe/Paris' PMT+0:09:00 STD>)
>>> date_paris.astimezone(pytz.utc).astimezone(pytz.timezone("Europe/Paris"))
datetime.datetime(2013, 9, 3, 17, 51, tzinfo=<DstTzInfo 'Europe/Paris' CEST+2:00:00 DST>)

How can I specify date and time in Python?

What is the object used in Python to specify date (and time) in Python?
For instance, to create an object that holds a given date and time, (let's say '05/10/09 18:00').
As per S.Lott's request, so far I have:
class Some:
date =
I stop there. After the "=" sign for, I realize I didn't knew what the right object was ;)

Simple example:
>>> import datetime
# 05/10/09 18:00
>>> d = datetime.datetime(2009, 10, 5, 18, 00)
>>> print d.year, d.month, d.day, d.hour, d.second
2009 10 5 18 0
>>> print d.isoformat(' ')
2009-10-05 18:00:00
>>>

Nick D has the official way of handling your problem. If you want to pass in a string like you did in your question, the dateutil module (http://labix.org/python-dateutil) has excellent support for that kind of thing.
For examples, I'm going to copy and paste from another answer I gave a while back now:
Simple example:
>>> parse("Thu Sep 25 2003")
datetime.datetime(2003, 9, 25, 0, 0)
>>> parse("Sep 25 2003")
datetime.datetime(2003, 9, 25, 0, 0)
>>> parse("Sep 2003", default=DEFAULT)
datetime.datetime(2003, 9, 25, 0, 0)
>>> parse("Sep", default=DEFAULT)
datetime.datetime(2003, 9, 25, 0, 0)
>>> parse("2003", default=DEFAULT)
datetime.datetime(2003, 9, 25, 0, 0)
To ambigous:
>>> parse("10-09-2003")
datetime.datetime(2003, 10, 9, 0, 0)
>>> parse("10-09-2003", dayfirst=True)
datetime.datetime(2003, 9, 10, 0, 0)
>>> parse("10-09-03")
datetime.datetime(2003, 10, 9, 0, 0)
>>> parse("10-09-03", yearfirst=True)
datetime.datetime(2010, 9, 3, 0, 0)
To all over the board:
>>> parse("Wed, July 10, '96")
datetime.datetime(1996, 7, 10, 0, 0)
>>> parse("1996.07.10 AD at 15:08:56 PDT", ignoretz=True)
datetime.datetime(1996, 7, 10, 15, 8, 56)
>>> parse("Tuesday, April 12, 1952 AD 3:30:42pm PST", ignoretz=True)
datetime.datetime(1952, 4, 12, 15, 30, 42)
>>> parse("November 5, 1994, 8:15:30 am EST", ignoretz=True)
datetime.datetime(1994, 11, 5, 8, 15, 30)
>>> parse("3rd of May 2001")
datetime.datetime(2001, 5, 3, 0, 0)
>>> parse("5:50 A.M. on June 13, 1990")
datetime.datetime(1990, 6, 13, 5, 50)
Take a look at the documentation for it here:
http://labix.org/python-dateutil#head-c0e81a473b647dfa787dc11e8c69557ec2c3ecd2

Look at the datetime module; there are datetime, date and timedelta class definitions.

>>> import datetime
>>> datetime.datetime.strptime('05/10/09 18:00', '%d/%m/%y %H:%M')
datetime.datetime(2009, 10, 5, 18, 0)
>>> datetime.datetime.today()
datetime.datetime(2009, 10, 5, 21, 3, 55, 827787)
So, you can either use format string to convert to datetime.datetime object or if you're particularly looking at today's date could use today() function.