How Much Should You Bet While Counting Cards?

How Much To Bet?

You are sitting at a blackjack table in a smoky casino roughly two decks into an eight deck shoe when it happens. It's a new round, and the table is littered with low cards, and each hit brings another. The next thing you know, the round is over, and the true count is +4. How much should you bet?

Card counters generally employ what is known as a bet schedule. For example, with a $10,000 bankroll, on a $5 minimum table with normal rules (6 decks, h17, DAS, DA2) we might bet as follows :

True Count	Player Bet
1 or below	$5
2	$10
3	$20
4	$30
5 or above	$50

Incidentally, you would want to bet all in red for TC 4 or below, and either all red or two green chips for TC 5. Don't mix colours because that will waste time as the dealer has to break down your bet for the eye in the sky. And don't bet odd numbers either, because that makes for complicated blackjack and/or surrender payoffs. As a card counter, you want things to go quickly. More rounds per hour means a higher hourly win-rate.

The Max Bet Bankroll

The easiest way to calculate your max bet is to start with your bankroll and work backwards. Let's say your bankroll is $20,000. You decide you want to have 200 max bets in your bankroll, ergo your max bet is $100.

200 max bets is a conservative but reasonable approach. Furthermore, you can reduce your ROR substantially by reducing your max bet if you go on a downswing. So if you drop down to $15,000, you might resize and cap out your max bet now at $80. We're going to avoid $75 because we prefer to bet in even numbers as it speeds up the game.

 A Scientific Approach

The scientifically optimal method of betting is to use the Kelly Criterion. Given a series of even money wagers with an edge, the optimal strategy is to wager a % of your bankroll proportional to your advantage. Or in the words of the venerable Edward Thorpe "If all blackjack bets paid even money, had positive expectation and were independent, the resulting Kelly betting recipe when playing one hand at a time would be extremely simple: bet a fraction of your current capital equal to your expectation." THE KELLY CRITERION... 

Essentially, Kelly betting is the fastest way to grow your bankroll. If you bet any more, downward swings are too likely to cripple your bankroll before you get to the "long run". If you bet any less, then you are simply sacrificing your winrate for no reason. 

Because blackjack is not a strictly even money game, it is important to bet only 70% of your advantage. So if you had a 1% advantage with a bankroll of $10,000 you would bet only $70.

Trip Roll Concerns

Another factor that can impact your bet sizing is your trip roll, meaning how much of your bankroll you have on hand. Well heeled professional blackjack players often keep a substantial portion of their bankroll in the bank or in a safety deposit box. If you are playing away from home, with limited ability to reload, then you might size your bets in such a manner as to ensure a minimal risk of trip ruin. After all, if you go broke in the first few hours, you won't be able to generate EV throughout the whole trip. So bet sizing can depend on how many hours you have left to play. As you get later and later into your trip, with fewer hours remaining, it might make sense to increase your max bet if you are still below your kelly optimal wagering but have restrained yourself to minimize the risk of trip ruin. 

Furthermore, you should always make sure you have at least another 4 or 5 bets behind you to back up any bet that you make. This is enough to cover any bets or splits that are likely to occur. There is a minute chance that you will end up wanting to make up to 8 bets in total, if you were to resplit 4 times and then double on each hand, but having 4 or 5 bets is enough. This is because the chance of needing more than that is remote. Possible, but remote. So if you make a bet with 5 bets to back it up, and you lose, then you should either resize down or quit.

Half Kelly Betting

Full Kelly betting is not for the faint of heart. If you have a 2.5% edge at say TC +5, Kelly would have you bust out 1.75% of your bankroll. Or $350 on a $20,000 bank. As anyone who has lost 10 or 20 max bets in a shoe can attest, the variance of full kelly can be sickening.

For that reason, some players prefer to bet only half kelly, especially if they have a large bankroll. This reduces the variance substantially. 

Conclusion

If you are interested in making a lott of money in blackjack, then you should learn about Kelly betting and how to apply it for optimal bankroll growth. Betting proportional to your advantage is a recipe for prosperity and success. There is a reason they call it 'Fortune's Formula'.