When looking into a StackOverflow question about surprisingly high memory use, I stumbled into this (under 3.10.1, Win64):

>>> import sys
>>> s = "1 2 3 4 5".split()
>>> s
['1', '2', '3', '4', '5']
>>> sys.getsizeof(s)
152
>>> _ - sys.getsizeof([])
96
>>> 96 / 8
12.0

That is, we allocated enough space in the list to store 12(!) elements, despite that only 5 are used. Other ways of building a 5-element list I've tried overallocate by at most 3 slots:

>>> sys.getsizeof([ch for ch in "12345"])
120
>>> sys.getsizeof([1, 2, 3, 4, 5])
120

(and 120 - 56 = 64, room for 8 pointers)

Then there's this curiosity, which allocates space for exactly the 5 needed:

>>> sys.getsizeof(list(tuple("1 2 3 4 5".split())))
96

(and 96 - 56 = 40, room for the 5 pointers needed)

I don't expect this to be consistent, but allocating space for 12 when only 5 are needed is unreasonable. Even allocating space for 8 is pushing it ;-)