Spans of the week vs Shift of weekdays

[treylav]

Hello!

Could you please help me understand the difference between some use cases of shift() and span()?

In my example, as I see it, both seem to do very similar things — one “shifts” the date to the zero weekday, while the other gets the start of the week’s range:

print(arrow.utcnow())
# >> 2025-10-12T21:12:25.465568+00:00
print(arrow.utcnow().shift(weekday=0))
# >> 2025-10-13T21:12:25.465593+00:00
print(arrow.utcnow().span('week')[0])
# >> 2025-10-06T00:00:00+00:00

Yes, of course, there must be some differences in how the time is handled, for example — but the completely different results make me think I’m misunderstanding the concept.

Could you please clarify the difference in this concrete use cases?

Thanks in advance!