Bet Size and Bankroll Size

Professional gamblers use a system called the Kelly Criterion to determine optimum bet size and/orBasil Nestor is the author of the new Playboy Complete Guide to Casino Gambling. This wonderful book teaches players how to avoid sucker bets and win more when playing gambling games.  He is also the author of The Smarter Bet Guide series for video poker, slots, craps, and many other books about gambling.  Basil's website is www.smarterbet.com  bankroll size. The way it works is that a player arbitrarily chooses either a bankroll amount or a bet size, and the Kelly formula produces the optimum size of the other variable. The resulting bet-to-bankroll ratio gives the player the greatest probability of winning and the lowest probability of losing everything.

Unfortunately, Kelly tells us to bet zero dollars when the casino has an advantage. That doesn’t help much when we’re playing slots. There’s a calculation similar to Kelly that estimates risk of ruin (the probability that your bankroll will dip to zero), but I won’t cross your eyes with either of these formulas.

Instead, I’ll just tell you that a bankroll for a two-to-three-hour session should be at least 250 times the size of your average bet when you’re playing penny and nickel slots. This doesn’t necessarily mean you should buy in for that amount, but having that money available will keep you playing for up to three hours in most circumstances, sometimes longer.

If you’re playing quarters, then your session bankroll should be at least 200 times the size of your average bet. For dollar slots and above, 150 bets should keep you going up to three hours.

Note that the number of bets needed for your session bankroll goes down as the denomination increases. That’s because quarter slots are generally looser (have a higher overall payback) than penny and nickel slots, dollars are looser than quarters, and so forth.

Video poker machines don’t get looser at higher denominations (though sometimes the pay tables do get better). In any case, all denominations of video poker require at least 150 bets for a three-hour session bankroll.

You should have at least 50 bets for table games such as blackjack and baccarat.

Why can a table-game bankroll be smaller? First, let’s remember that table-game bets are usually bigger in actual dollars. So the total amount required for a blackjack game may be more than the amount for a video poker game, even when a blackjack bankroll contains fewer bets.

On a per bet basis, table games require smaller bankrolls because they tend to have lower volatility compared to slots and video poker. In other words, there are fewer extreme swings between winning and losing. Most table bets pay 1:1, or sometimes 3:2. Roulette’s top payout is 35:1. In contrast, slot games have jackpots that pay 1,000:1, 10,000:1, and even more. The money for those big jackpots has to come from somewhere. Games with big payoffs tend to have fewer small wins and longer stretches of losing.

When calculating the size of your bankroll, also keep in mind that an average bet is not necessarily the lowest bet. For example, if you’re betting max credits on a 25-cent video poker machine, and you’re playing single hands, then each bet is $1.25. Multiply that by 150, and your session bankroll should be at least $187. But if you’re playing ten hands per game, then each bet is $12.50, and the session bankroll should be at least $1,875. Similar caveats apply if you’re covering a lot of numbers in roulette and craps, or playing two or three spots in blackjack.

If all this math makes your head spin, don’t fret. Just take your base bet and tack two zeros on the end. Double that amount. That’s 200 bets. You’ll rarely go wrong with a session bankroll of 200 bets for slots, or 50 bets for table games.