God lets everything happen for a reason. It's all a learning process, and you have to go from one level to another.
Mike Tyson

I was playing in Vegas and some of my buddies was standing behind me and watching when the following hand took place. It was folded to the small blind. His name was Sandy and he was from Ohio and probably around 40 years old. He had told me earlier that he was the best player at the table and that I was (probably) the second best player. I didn't agree with him but held my mouth shut -  not to ruin the good atmosphere at the table. He raised to 7 - it was a 1-2 table at MGM and me and my friend Laust was having fun in this (for us) slightly drunken cashgame. I looked down at big slick (ace,king) and reraised to 21. He looked up at me with a very puzzled expression -  and then he 4-bet to 70 (we both had around 320 or so from the beginning). Oops first time anyone at the table - except a few short stacks - had 4-bet. I folded my hand and showed it to my friends and Sandy. They (all online pros from the office) were just looking in disbelief: did you just fold ace king??? Yup and Sandy was a real sport so he showed his hand and as I had figured: two nice aces!

Can't say I did a soul read - it is just that this guy - Sandy - would never have 4-bet with anything but aces and maybe (only maybe!) kings! This is quite typical for livegames. But online is a completely different thing! It plays much more aggressive preflop (also why a lot of liveplayers feel they get blown away). Here 3-bets is normal and 4-bets too! So what to do with 4-bets? Uncle Sune is here to help you out. Today we will look at bet-sizing:

1) Size of 4-bets
Let's see an example with normal stacks (100 big blinds) at 200 NL. Player 1 opens to 6 in the cut-off, Player 2 3-bets to 18 from the button. The blinds fold. What size should Player 1 choose for a 4-bet?
Here is how to think about it. At 3-bets I usually choose the sizes like this:
In position: 3x the original bet (6 ---> 18 etc.) .
Out of position 3,5 or 4x (if it is very small) the original bet. (4--->16; 5--> 18 or 6-->21). Typically it centers around 10x effective stacks. Now with 4-bet this is no longer a viable method because the bets becomes to big! If Player1 says 3,5 times the 3-bet he ends at 63. But that is too big because he has already committed more than 25% of his stack and will have to call an all-in with most hands. Most players (at lower stakes) will call an all-in when they 4-bet, so whats the problem? The problem is that you don't have 4-bet bluff range at all! Another problem is one of leverage (creating unnecessary deadmoney)- you don't need to bet so big to put your opponent in a fold or shove spot.

So if your opponent see you 4-bet he know it is for value (no fold equity) and will therefore never spazz out and shove a bad hand (in this context say JJ). This will make it much harder to get value from your good hands. Guys who see that you 4-bet percentage is 2,1 percent will know that it consists of exactly AA-KK and AK!

So they will fold a lot... especially guys who 3-bet a lot will muck just about anything when facing a 4-bet. So what to do? 4-bet bluff of course! Therefore it is of paramount importance to bet the right size. The right size is at most 27 (25 is a good rule of thumb) percent of the smallest stack involved - if that is silly (say one player has a half stack) then shoving is better! So in the above situation a 4-bet in the range of say 44-50 is suitable. I see a lot of players make their 4-bets too big and they are not getting anything extra for it. Next up: when and who to 4-bet as bluff and for value.