Playing 5/10

Assume you open to $40 in EP. You get 3 bet to $120 by MP who is a good tightish but also sometimes tricky player. You're $1800 effective.

What does the book say your 4 bet size should be when it gets back to you heads up?

You could call this 2/5 and cut everything in half. I dont think it matters really.

If you 4 bet you should be making it around 450.

Pretty sure Upswing would suggest ~$350, but I've always thought the ~2.5x IP and ~3x OOP were way too small and not well suited for live poker.

$400-$450 is what I'd personally do.

450 seems a little big to me. I might go that size vs a sticky whale type, but in general, I’d prefer 350ish.

If I'm in position I'd make it 350.

Some of this (in my 2/5 world) depends on my range and what I know about my opponents range. Some players (with a fold button) I want to legit narrow they’re light 3bet range so I go less. But calling station ‘pros’ who think they’re being tricky by calling with anything suited I punish with a higher bet for value.

Not a great story, but you can’t be wrong with $350+. Especially if your 4bet range is more complicated than KK/AA.

Marsh

In this spot , given 180BB stacks I would make it 400. Making it 350 or less opens the door for him to call you in position with a wide range with decent implied odds.
In 250BB+ situation I would be making it closer to full 4x (450-480) depending on the opponent. Probably 450 based on the given description
Against whale in deeper stacks I would just make it 500.

In position in 180BB effective I would make it 320
250BB effective - 360$

If you make it 360, he doesn't have odds to setmine and doesn't have odds to call with other speculative hands like suited connectors or suited aces. If he calls, he is making a mistake.

If he does call bigger bets with speculative hands, by all means bet more. But chances are if you bet more, the less the chance he makes a mistake. Moreover, if you make it 360, the resulting SPR is 2 whereas if you make it 450, the resulting SPR is 1.5. Neither is high, so chances are if you have top pair you will get committed; conversely speculative hands like suited connectors don't really have any maneuvering space to run big bluffs and put pressure on you.

In other words, bet smaller and don't worry he ll suck out on you; if he does, he made a mistake pre.