Card counters operate under the (correct) assumption that even perfect blackjack strategy is a losing proposition. That’s because basic strategy gives no indication of the likelihood of a dealer or player bust. Basic strategy requires you to hedge your bets in certain playing situations, meaning you are just as likely to win as to lose.
Keeping a running count improves on basic blackjack strategy by indicating when you can deviate from that strategy and still have a decent chance of winning. If you know there are more small cards than large ones, you can safely take hits on those pesky 15 and 16 point hands and improve your chances of beating the dealer. You can use a running count to know when to increase your bet size to maximize your profits, and when to decrease your bets to protect yourself from potential losses.
These changes in the bet size are known as a “betting spread,” a tool used by counters to increase profits and decrease losses without drawing the attention of the casino. Ideally, you can make small changes to your bets without the casino figuring out that you’re a card counter and (politely) asking you to leave.
Betting Spreads and Positive Expectation
The name of the game in card counting is turning blackjack into a positive expectation game. Peter Griffin’s book “The Theory of Blackjack” worked out some numbers pertinent to card counters. Using standard Las Vegas rules and a basic High-Low card counting system, a player’s advantage with perfect strategy when the count is zero is -0.56%. According to Griffin, each increase by 1 of the running count improves the player’s advantage by +0.5%. Naturally, every decrease by 1 of the count reduces the player’s advantage by 0.5%.
Positive Count and Percentages
We know that, statistically, a standard Vegas game of blackjack will only offer certain counts some of the time. Positive expectation only happens with a +2 count, which will only happen about 8% of the time. Truth be told, a positive count can only be expected about 18% of the time you’re playing–that’s why it is important to spread your bets, even if you’re keeping a running count and playing according to basic strategy.
What’s the Best Bet Spread?
People much smarter than you and me have determined that a bet spread between 1 and 5 units is the best way to avoid undue attention from the casino. By this reckoning, you should bet 1 unit for a +1 count, all neutral counts, and all negative counts. A +2 count means 2 units, a +3 count means 3 units, a +4 count means 4 units, and anything over +4 means you bet 5 units. Going over 5 units is likely to attract unwanted casino heat.
Using this system and perfect blackjack strategy, you can expect a positive return of about 0.14%. You’re not going to get rich with small wins under this system, but it will turn a negative expectation game into a positive one.
Larger Bet Spreads
The only way to increase your expectation is to use a 1-10 unit bet spread, which is sure to get you kicked out of any casino eventually. Still, as long as you can get away with a 1-10 unit spread, you can play with an edge of about 0.57%, or about three and a half times greater than with a 1-5 unit spread.
Since casinos have implemented rules and strategies to counteract card counting, the easy to beat blackjack tables have disappeared. Casinos are now instituting a 6:5 blackjack payout rule, for instance, that automatically makes the game not worth the time it takes to count cards and develop a bet spread. Perfect blackjack strategy is often as good as you can get at today’s blackjack tables, since even the most aggressive counting and bet spreading gives you only about a .5% edge.