def time_in_24h(time,time_day): #time is eastern time
''' (number, str)--> number
This function converts a 12-hour time, represented by am/pm,to its equivalent 24-hour time.
Returns time in the 24-hour format.
'''
cCentral = 'Central Time(CT)' #-1 hour offset
mMountain = 'Mountain Time(MT)'#-2 hours offset
pPacific = 'Pacific Time(PT)'#-3 hours offset
eEst = 'EST is'

if time_day!='pm' and time_day!='am':

    print('Input is not in the right format')  #this is where input is not in the right format
    return 0

else:
    print(time, time_day, eEst, time-1, cCentral)
    print(time, time_day, eEst, time-2, mMountain)
    print(time, time_day, eEst, time-3, pPacific)

time_in_24h(7,'am')

7 am EST is 6 Central Time(CT)
7 am EST is 5 Mountain Time(MT)
7 am EST is 4 Pacific Time(PT)

1 pm EST is 12 pm Central Time(CT)
1 pm EST is 11 am Mountain Time(MT)
1 pm EST is 10 am Pacific Time(PT)

def to_24hour(hour, ampm):
    """Convert a 12-hour time and "am" or "pm" to a 24-hour value."""
    if ampm == 'am':
        return 0 if hour == 12 else hour
    else:
        return 12 if hour == 12 else hour + 12

def to_12hour(hour):
    """Convert a 24-hour clock value to a 12-hour one."""
    if hour == 0:
        return (12, 'am')
    elif hour < 12:
        return (hour, 'am')
    elif hour == 12:
        return (12, 'pm')
    else:
        return (hour - 12, 'pm')

def time_in_24h(time,time_day): #time is eastern time
    ''' (number, str)--> number
    This function converts a 12-hour time, represented by am/pm,to its equivalent 24-hour time.
    Returns time in the 24-hour format.
    '''
    cCentral = 'Central Time(CT)' #-1 hour offset
    mMountain = 'Mountain Time(MT)'#-2 hours offset
    pPacific = 'Pacific Time(PT)'#-3 hours offset
    eEst = 'EST is'

    if time_day!='pm' and time_day!='am':

        print('Input is not in the right format')  #this is where input is not in the right format
        return 0

    else:
        est_24hour = to_24hour(time, time_day)
        hour, ampm = to_12hour((est_24hour - 1 + 24) % 24)
        print(time, time_day, eEst, hour, ampm, cCentral)
        hour, ampm = to_12hour((est_24hour - 2 + 24) % 24)
        print(time, time_day, eEst, hour, ampm, mMountain)
        hour, ampm = to_12hour((est_24hour - 3 + 24) % 24)
        print(time, time_day, eEst, hour, ampm, pPacific)

>>> time_in_24h(1, 'pm')
1 pm EST is 12 pm Central Time(CT)
1 pm EST is 11 am Mountain Time(MT)
1 pm EST is 10 am Pacific Time(PT)

now = datetime.datetime(2014, 3, 14, 12, 34)

et = pytz.timezone('America/New_York')
ct = pytz.timezone('America/Chicago')
mt = pytz.timezone('America/Denver')
pt = pytz.timezone('America/Los_Angeles')

now_et = et.normalize(et.localize(now))
now_ct = ct.normalize(now_et.astimezone(ct))
now_mt = mt.normalize(now_et.astimezone(mt))
now_pt = pt.normalize(now_et.astimezone(pt))

print('{} Eastern in various other timezones:'.format(now_et.strftime('%I %p')))
print('Central : {}'.format(now_ct.strftime('%I %p')))
print('Mountain: {}'.format(now_mt.strftime('%I %p')))
print('Pacific : {}'.format(now_pt.strftime('%I %p')))

def time_in_24h(hours, am_or_pm):
    """Convert to 24 hours."""
    if not (1 <= hours <= 12):
        raise ValueError("hours must be in 01,..,12 range, got %r" % (hours,))
    hours %= 12 # accept 12am as 00, and 12pm as 12
    am_or_pm = am_or_pm.lower()
    if am_or_pm == 'am':
        pass
    elif am_or_pm == 'pm':
        hours += 12
    else:
        raise ValueError("am_or_pm must be 'am' or 'pm', got: %r" % (am_or_pm,))
    return hours

from datetime import datetime

def time_in_24h(hours, am_or_pm):
    return datetime.strptime("%02d%s" % (hours, am_or_pm), '%I%p').hour

from datetime import datetime, time
import pytz

def astimezone(aware_dt, dest_tz):
    """Convert the time to `dest_tz` timezone"""
    return dest_tz.normalize(aware_dt.astimezone(dest_tz))

def print_times(hours, am_or_pm, date=None, is_dst=None):
    source_tz = pytz.timezone('US/Eastern')

    # 2. add date
    if date is None: # if date is not specified; use today
        date = datetime.now(source_tz).date()
    naive_dt = datetime.combine(date, time(time_in_24h(hours, am_or_pm), 0, 0))

    # 3. create timezone-aware datetime object in the source timezone
    source_dt = source_tz.localize(naive_dt, is_dst=is_dst)

    #NOTE: these timezone names are deprecated,
    #      use Continent/City format instead
    fmt = '%I %p %Z'
    for tzname in 'US/Central', 'US/Mountain', 'US/Pacific':
        dest_dt = astimezone(source_dt, pytz.timezone(tzname))
        print("{source_dt:{fmt}} is {dest_dt:{fmt}} ({tzname})".format(
            **locals()))

>>> print_times(7, 'am')
07 AM EDT is 06 AM CDT (US/Central)
07 AM EDT is 05 AM MDT (US/Mountain)
07 AM EDT is 04 AM PDT (US/Pacific)
>>> print_times(1, 'pm')
01 PM EDT is 12 PM CDT (US/Central)
01 PM EDT is 11 AM MDT (US/Mountain)
01 PM EDT is 10 AM PDT (US/Pacific)
>>> print_times(9, 'pm')
09 PM EDT is 08 PM CDT (US/Central)
09 PM EDT is 07 PM MDT (US/Mountain)
09 PM EDT is 06 PM PDT (US/Pacific)

>>> from datetime import datetime
>>> from pytz import timezone
>>> import pytz
>>> central = timezone('US/Central')
>>> mountain = timezone('US/Mountain')
>>> mountain_date = mountain.localize(datetime.now())  # set time as right now mountain time
>>> fmt = '%Y-%m-%d %I:%M:%S %p'
>>> central_date = central.normalize(mountain_date.astimezone(central))
>>> print central_date.strftime(fmt), central, 'is', mountain_date.strftime(fmt), mountain
2014-03-15 07:29:17 PM US/Mountain is 2014-03-15 08:29:17 PM US/Central

>>> def time_in_24h(hour, am_pm):
    """hour is an integer that represents eastern time on the 12-hour clock, and am_pm
       will take any string that begins with 'a' or 'p'"""
    if not am_pm.lower().startswith(('a', 'p')):  # return None if am_pm does not start with 'a' or 'p'
        return
    central = timezone('US/Central')
    mountain = timezone('US/Mountain')
    pacific = timezone('US/Pacific')
    eastern = timezone('US/Eastern')
    if hour == 12:
        mod_hour = 0 if am_pm.lower().startswith('a') else 12
    else:
        mod_hour = hour + 12 if am_pm.lower().startswith('p') else hour  # add 12 if am_pm starts with 'p', but keep original hour for display purposes
    fmt = '%H:%M %p'
    eastern_time = eastern.localize(datetime(1900, 1, 2, mod_hour))
    for tz in (central, mountain, pacific):
        d = tz.normalize(eastern_time.astimezone(tz))
        print hour, am_pm, 'EST is', d.strftime(fmt), tz  # tz displays as pytz timezone; can change


>>> time_in_24h(1, 'am')
1 am EST is 00:00 AM US/Central
1 am EST is 23:00 PM US/Mountain
1 am EST is 22:00 PM US/Pacific
>>> time_in_24h(9, 'pm')
9 pm EST is 20:00 PM US/Central
9 pm EST is 19:00 PM US/Mountain
9 pm EST is 18:00 PM US/Pacific