How much of your stack is it okay to 4 bet bluff and fold preflop?

There’s no such thing as “pot committed” in a cash game. The only real question is whether or not you have pot odds to call a 5-bet jam after your 4 bet. If you have 4 bet large enough, it’s probable that you would. After all you very rarely are going to have less than about 20% equity in a spot like this. With 20% equity you could call if your 4 bet amount was 60 bb or more since with 100 bb stacks and a 60bb 4 bet you are risking 40bb to win 160, so breakeven is 40/(40+160) = 20%. If your expected equity is lower (you 4 bet AK and are against a player who only shoves AA for example), you can fold an even higher 4 bet.

Like I said “pot committed” is a fallacy in a cash game. In a tournament it applies because folding would leave a crippled stack that has little chance of getting you anywhere in the tourney. In a cash game you simply reload to a full stack, so the concept does not apply. The only question is whether a call is +EV or not. If not, fold, regardless of how big your 4 bet was.

EDIT: I saw 100BB vs 100BB and assumed you meant cash since those stacks would rarely happen in most tourneys. I realized on rereading that you never specifically said cash game, so please disregard my post if you did intend to ask about tournament play. If that is the case though you should post your question in the right forum.

Just to further illustrate the idea that “pot committed” is not meaningful in cash games, here’s an extreme hypothetical. Suppose you are in a live 1/2 game. You are SB, villain is BB. Folds to you and you open to 10 with AA. BB calls. Flop is KKK. You intend to shove your remaining 190, but one $1 chip gets left behind. You did not say all in so dealer announces a bet of $189. Villain raises all in and accidentally flashes KQ. Should you call?

The answer is no. You should fold and save yourself $1. You would be risking $1 to win $399 (ignoring rake for simplicity - rake makes calling even worse). You need 1/(1+399) = 0.25% equity to make calling breakeven. You only win with runner-runner aces which has a 1/1980 chance, about 0.05%. This is less than required so folding is correct.

Yes I am talking about cash games only. I suppose I could change my question a bit to say how much is too much for a 4 bet bluff? Like if I 4 bet bluff to 40BB and fold A5s, that's likely a good fold against most opponents however the 40BB bet itself feels very wasteful in that situation.

This didn't used to be a problem but these days I am facing such outrageously large 3 bets IP which ends up ballooning my 4 bet bluffs to be uncomfortably large. I have already decided to incorporate 2x 4 bet into my game something that I never used to do before.

Another option is to simply never 4 bet in such situations and just start calling a lot including all the premiums. But for now I only call such bets when a rec in the middle also calls as then the reg has to remain more honest post flop.

~1/3 of your stack would be the tipping point.

You should call more these a lot pre is the answer. The ridiculous 3-bet sizing leads to too big c-bet etc.

if your referring to live poker, which it sounds like you are..absolutely flat. when i moved up to in stakes this is something i noticed and started exploring in monker ( albeit years ago now) and flatting is so much better in multiway IRL. Also just jamming AA,KK is good too. ALOT of recs will put you on AK if you rip it pre and call you pretty light ( mid PPs 88-JJ i see alot). obviously this doesnt work against better players but better players dont 3b 7x either lol.

Typical 4bet sizes are between 20 and 28bb , depending on the size of 3bet you are facing and positions. I wouldn't go much more than this. If a 'sensible' size takes you to more than 1/3rd of your stack just shove instead.

depends on how bad of a hand you're 4betting