week starts at Sunday or Monday??

Markus Kuhn Markus.Kuhn at cl.cam.ac.uk
Mon Oct 2 13:09:53 UTC 2000

Christoph Bugel wrote on 2000-10-01 08:08 UTC:
> now that I decided that days are niumbere 1 to 7, 
> what is day 1 ???
> is it Sunday, or Monday?
> what is the Right Thing to do?

ISO 8601: Monday=1, Sunday=7
C:        Sunday=0, Saturday=6

So there is at least agreement that Moday to Saturday have the numbers
1-6, only the Sunday can choose to be the first or last day of the week.

ISO 8601 establishes a week numbering scheme that is used at least in
many European countries widely for industrial planning (and more
recently also for naming weekly computer logfiles). Today week 40 of
2000 started. The ISO week numbering scheme starts the week on Monday
and since you decided anyway to start at 1, then I would suggest the ISO
convention is the way to go.

For details, please read


There is no real "Right Thing" anyway, because weeks and week days are a
very arbitrary cultural convention that seems not to be based on any
more fundamental reasons.


Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org,  WWW: <http://www.cl.cam.ac.uk/~mgk25/>

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