database sizing estimates using partitioned indexe

We partitions by day and by month depending on the table. All of our
partitions have names of the form

PART_YYYYMMDD or PART_YYYYMM

I am trying to calculate sizing estimates/day and by month (so they can stay
ahead of adding storage).

since all my partitions have the same name, user_segments is not useful.
for data I was using using_tab_partitions and taking blocks*blocksize to get
the size/day.

I see "leaf blocks" in user ind_partitions. Not sure if that is enough
blocks to get a good estimate per day. Note that 1 partition is one day or 1
month.

any suggestions ?

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