As a level 6 player, it is impossible to upgrade a portal to level 5 on your own:
2*6 + 2*5 + 4*4 + 2*3 = 4.75
So the portal will be Level 4 at max. It also shows "L4" in the app when you select the portal.
When hacking, it will yield mostly items of level max(portal lvl, player lvl), uncommonly of that +/-1 and very rarely +/-2
My question is: Does hacking a level 4.75 portal have the same item drop probability as a plain level 4 portal? Or will I get level 5 items more often?
There was a similar question a few months ago, but the answers didn't rely on hard evidence or credible sources:
What determines the quality of items obtained from a portal hack?
Edit to make the difference more obvious:
I do NOT want to know what other factors might influence the items dropped. This question is specifically about whether the portal level is counted discrete (1, 2, 3, 4, 5, …) or if intermediate levels (4.125, 4.25, 4.5, …) exist for calculation.
Best Answer
It looks like in the portal hacking phase, the level used is the "rounded" level.
It sounds logical that items dropping is related to this "rounded" level.
As far as I experienced it (i'm now level 7), to get high level items, I have to hack "real" high level portals.
A portal at level 5.75 ( 7+6+6+6+6+5+5+5, made by 1 L7 and 1 L6 player) will still give me less high level items than a real L6 portal ( 7+6+6+6+6+6+6+5 made by 1 L7 and 2 L6 players).
I never get any L8 items from portals that were at lavels 5 or 5.25 or 5.75, the first time I got some was when hacking a real L6 portal :D