This feels like roughly 40% of starting hands to me.
This is the classic 50% line of starting hands. But with players yet to act, I don't think the calculation can be that simple. From the cutoff there are 3 players yet to act and they would be getting 2-1 pot odds if hero calls. And I do think all roads point to the best way to exploit the blind all in is to isolate. Doing that effectively means players left to act are only getting 2-1 on villains effective stack and even money on the amount over that.
So I think we have to factor in how as hero, our actions influences those left to act.
If we were last to act, I think this math is right, but I think we need to assume to be somewhat tighter becose of the intervening players and because I think we don't want to have a calling range here. If we are playing this pot based on knowing utg is in the dark, we should be playing to isolate.
If the pot is unraised here, I probably have something like a 20% raise and an additional 20% calling frequency. If feels to me like it would probably adjust to no calling range by moving half the hands to raises and half to folds. So shoving the top 30% and folding the rest "feels" right to me here.
I'm not sure I would put JTo that high on the list. My instinct is that's a fold, but
@Legend5555 's list makes me reconsider given it's down to J8o for j-hi holdings.
I think the the fact hero is not last changes everything. If hero is last, then I think
@Legend5555 's list is the clean and simple answer. I think we have to tighten up somewhat because of the other players and we need to play a shove-fold strategy because of the other players.
But I guess if I am thinking top 30% of hands on my mind without looking it up, I would think all pairs, any suited Broadways, suited connectors 98 and up, suited one gaps j-9 and up, A9s, A8s, AJo+, KQ, KJ, QJ.
I would think JTo is on the outside and I would fold. But maybe it's closer than I think.
All of that being said, in the grand scheme of poker, this situation is so infrequent, it's probably not that costly in the long run to have an imperfect answer, if it's way to tight or way too loose.