The trouble with the strength tables is they require a bit of
experience on the part of the timber grader. Two pieces of the the
same kind of wood may have very different strengths because of knots
and other defects. Since you are building a verandah rather than a
multistorey carpark just use a bit of common sence and err on the side
of overkill. I built a verandah recently with 6 inch square oak posts.
Plenty of overkill there but green oak only cost =A315 per cubic foot
and big post look nice. I expect posts of a quarter the crossectional
area (3 x 3 inch) would have been more than adequate. Pine is more
likely to rot at the bottom end than oak. Larch, Douglas fir and cedar
are the more durable softwoods.