Know bloat percentage after auto vacuum

Hi all.

We have the table with 2 months data (approx 450GB). We deleted 17 days of
data and auto vacuum performed on the table.new insertions are utilizing
that space,we want to perform the vacuum full and reclaim the space at os
level but don't know how much free (unused) space available.how can we get
the details.

Thanks in advance.

Regards,
Satish.