Converting Excel dates to UTC Epoch and back

gistfile1.txt

# The key thing to notice here is that Excel dates are in seconds since
# December 30, 1899, expressed in days.

#!/env/python
from datetime import datetime, timedelta, timezone

def epoch2excel(epoch, tz=None):
    if tz is None:
        tz = timezone.utc
    dtepoch = datetime.fromtimestamp(epoch, tz)
    temp = datetime(1899, 12, 30, tzinfo=timezone.utc)
    delta = dtepoch - temp
    return float(delta.days) + (float(delta.seconds) / 86400)

def excel2epoch(exceldate, tz=None):
    if tz is None:
        tz = timezone.utc
    temp = datetime(1899, 12, 30, tzinfo=tz)
    exceldate = float(exceldate)
    days = int(exceldate)
    seconds = (exceldate - days) * 86400
    date = temp + timedelta(days=days, seconds=seconds)
    epoch = datetime(1970,1,1, tzinfo=timezone.utc)
    return (date - epoch).total_seconds()

# # Unix
# $ date +%s
# 1377652599
# 
# epoch = 1377652599
# exceldate = epoch2excel(epoch)
# print(exceldate)
# 
# 41514.0532292
# 
# backto_epoch = excel2epoch(exceldate)
# print(backto_epoch)
# 
# 1377652599.0