Raising amounts and the math behind it all

I've heard that the standard opening raise is 3XBB because its big enough to be a healthy raise but not so big that you become pot-commited with a weaker hand if somebody behind you comes over the top.
Is there some math behind this, like some kind of pot odds?
I'm generally good with math but am lost with math applied to poker
i guess i just never studied poker in that sense.
anyways does anyone know the technical reasoning behind this?
(aside from disguising the strength of your hand by making your bet the same size every time as players such as Ferguson have suggested)
also is there a standard re-raise?Pot Size? or 3 times the raise (9XBB)??

-ChuckTs

When you raise Chuck, you are trying to thin the field and stop the Blinds getting a free / cheap look at the flop (and hitting the "Big Blind Special") but you also need to avoid betting too much in relation to the pot (i.e risking 1000 chips for 100 pot, where you are only likely to be called by a better hand). You want SOME action post-flop, so a 3-4 BB raise is about right. If you bet more with big hands and less with small hands astute players will pick up on this, so either keep raises standard (a la Ferguson) or random (a la Harrington) to throw opponents off guard.

If I remember correctly, Ferguson bets something like 5 x BB if he's opening , 3-4x BB if he's in the middle, and 2x if he's near the end. The idea is you want to bet just enough so that the board has incentive to fold, and you won't get more than 2-3 callers. I imagine he ups the middle/end bets if he's got a lot of limpers.

I usually like to use the methods of Phil Gordon. Raise 2.5x to 3.0x the blind in early position, 3.0x to 3.5x in middle position, 3.5x to 4.0x in late position and 3.0x times in the blinds. This method has worked great for me. In early position you risk less chips when you are out of position and it encourages a couple of callers when you have a powerhouse hand. When in position with the larger raise you are putting pressure on the blinds with the bet. Also when you are in better position you are building a bigger pot to be won. Hope this will or can help for you and thank Phil Gordon if it does.

The math behind raising is quite simple...make them pay too much for their draws. It requires putting a man on a hand, then making him get incorrect odds to call. like a man on a flush draw needs rougly 4:1 to make a call...so make him pay 2:1 and you can often make him fold.

Some good posts here, though to answer the original question: the reason for raising 3x/4x the bb. As stated above, you want to make it mathematically incorrect for them to call and see a flop, whereas if you just raised 2x the bb then the player in the bb is most likely going to call with almost any hand as hes already commited for one bet and will be getting the correct price to put in just another one bet to see a flop in most cases (as AK is hardly even enough of a favorite against 72 for those odds). As for standard reraise sizes these seem to work on the same principle, I am not a no limit professional but you would normally want to raise them at least 3x their original raise as to make it mathematically incorrect for them to call, so if someones raised to $100, you might want to reraise to $300.

I hope this has been of some help

When you bet preflop, your making either a purchase or an investment and the amount of your bet has a lot to do with what you're hoping to achieve and how many and who are betting after you.

When you just raise, your hoping to achieve 1 of 5 things.

1) Buy the pot outright. 1st in and raising. In early position you might try this with 88-JJ. This will be an expensive purchase. (Cost = 5 to 8 x BB)
2) Buy position. You want to do this with an Ace or King with a medium kicker. You don't mind too much if the blinds or an early caller match, but you want to be looking down hill at them when they do. Not quite as pricy as the pot grab. (Cost = 3 to 6 x BB)
3) Build the pot. This might be used with high suited connectors, medium to small pocket pairs or other speculative hands. This is best done when your expecting a multi-way pot and minimum bet is not likely to scare anyone off. You want to build the pot, but maintain your pot odds. (Cost = 2 x BB)
4) Your buying respect. In this case, your cards don't matter. Your playing out of position with the intent of leading out with a big bet on the flop. a healthy but not obnoxious raise will make anyone acting behind you stand up and take notice. (Cost = 3 to 5 x BB)
5) Value bet. Nothing fancy about this. You have a playable hand and don't want to give anyone a cheap look at the flop. Top 10 starting hands. (Cost 3 to 4 x BB)
These amounts are based soley on my own experience and are certainly up for debate.