## Better Betting 2 - Bet Sizing Calculator (Long Overdue)

A long time ago I wrote an introductory post addressing some technical aspects of bet-sizing, with an emphasis of betting to get all-in by the river. I introducedÂ alpha, Î±Â as the ratio of the bet-size to the current pot.Â

A quick reminder:

Â A pot-sized bet has an Î± of 1. A half-pot-sized bet has an Î± of 0.5. When theÂ SPRÂ is 13 we can make a series of three bets with an Î± of 1, concluding with a final all-in bet. For example, with a \$130 stack and a \$10 pot, we can bet pot on the flop, turn and bet all-in for pot on the river (\$10, \$30 and \$100 bets).

CalculatingÂ appropriateÂ bet sizes when the pot-to-stack ratio (PSR) is not 1, 4 or 13 is not simple. For example, with a PSR of 7 it is not immediately obvious what fraction of the pot to bet, given that you want to be all-in in three streets with the sameÂ Î± on each street. In order to assist those who are interested in these calculations, I wrote a little spreadsheet that can instruct you of these "perfectÂ Î±" bet-sizes. You can "Save a Copy" if you want to enter your own values (you will need a Google account).Â

In itself, betting with equalÂ Î± on each street isn't *that* important. However, a few minutes spent with the calculator establishing the SPR that make it awkward to get all-in over 2- or 3- streets can be of great use when planning a hand preflop, or deciding on your bet or raise sizing in general.Â Â One great example would be re-raising an unpaired high-card hand preflop, a situation in which we are deliberately bloating the pot so that if we hit top pair we can get all-in easily with three smallish bets, or, if we choose, two larger ones.Â CertainÂ SPR make this a lot easier than others; there are manyÂ variablesÂ to consider, but these ideas can all be contained within one question, "What will the SPR be if I get called?". It might be worth playing around with the calculator and thinking about your raise sizing, so you can plan your postflop bet sizes in advance.

### jjd323 posted on May 29, 2010 at 19:02 PM

You can check if you are using the calculator correctly: the 2-street alpha for a PSR of 7 is 1.44; the 3-street value is 0.73 (roughly speaking, a series of three 3/4 pot-size bets).

### Slowjoe posted on May 30, 2010 at 16:07 PM

I think that you should use a different name from alpha for this, since alpha is defined as a constant in Maths of Poker with the value p/(1+p).

Perhaps you could use rho for ratio?

### jjd323 posted on May 31, 2010 at 18:35 PM

Slowjoe, I'm aware of the alternative usage of Î± in MoP. However, given the provision of a clear definition for my parameter, and its limited usage outside the context of this discussion (so far, confined to my blogspace), I'll stick with Î±. Also, without wanting to nit too greatly on your comment - Î±, as defined by Chen and Ankerman, is not a constant - rather, it is a variable in p. Furthermore, I don't know the alt-code for rho (Ï).

### Slowjoe posted on June 03, 2010 at 17:18 PM

Ok, thanks for considering the suggestion. And my bad re: the constant. Had a brainstorm.

I think that what you are doing is quite useful, and so likely to leave your blog-space.

### jjd323 posted on June 03, 2010 at 19:10 PM

SlowJoe, maybe it would be a good idea to contact me via Skype - same username as on DC. We can chat about the future articles. It would be useful for me to bounce ideas of an interested party before I publish them.