Back
Blackjack Deviations Explained | LeoVegas

Blackjack Deviations Guide

What are blackjack deviations? Blackjack deviations are strategic adjustments that break from basic strategy, tailored to current table conditions. Without these deviations, you risk playing mechanically in robot mode, missing out on potentially profitable opportunities. In this guide, we’ll discuss how incorporating deviations into your blackjack game can give you an edge.

Table of Content:

Introduction to Blackjack Deviations

It’s OK to ask, what are blackjack deviations? However, a more precise question should be “What are deviations in blackjack?” This is the right question to ask because there are two types of deviations in blackjack: Betting deviations involve adjusting your bet based on the true count. i.e. you bet more when the true count suggests you have an edge, and less when the odds are less favourable.

Playing deviations involve making moves that deviate from basic strategy based on the current count. i.e. You would hit 12 against the dealer’s 2 unless the true count is 3.

At this point, you might be wondering what true counts and basic strategy are. A true count comes from card counting, and it tells you the number of high-value cards left in each deck of the shoe. You can learn more about counts in our guide to card counting.

Basic strategy is a set of pre-defined moves based on a mathematical principle known as equity. Put simply, you can simulate scenarios millions of times to see which move is more profitable in the long run, i.e. which move has the most equity. Experts have already done this which is why you can use basic strategy charts to determine the optimal move - whether to hit or stand - on any blackjack hand against any dealer card.

Importance of Deviations in Blackjack Strategy

Blackjack deviations account for table dynamics. Blackjack isn’t played in a vacuum, so there are times when basic strategy falls short. That’s why it’s called basic strategy. The prescribed moves account for all things being equal, but equality shifts throughout the course of the game.

In technical terms, the edge moves depending on the true count. Sometimes, the dealer has more of an edge (when the true count is 0 or below), and sometimes, the player has the edge (when the true count is 2 or above).

Ebb and flow with the game’s dynamics. That means betting less and largely sticking to basic strategy when the dealer has an edge. Conversely, betting more and deviating from basic strategy are appropriate when holding a favourable edge. This approach helps minimize potential losses when at a disadvantage and maximizes potential wins when in a favourable position.

Types of Blackjack Deviations

The definition of blackjack deviations is fairly simple to understand. However, before you can implement the common and uncommon blackjack deviations listed below, you must understand basic strategy. Moreover, you must be able to count cards.

Without these two skills, you won’t know what the right moves are, let alone how to deviate from them. Assuming you’ve acquired those skills, here are the most common deviations in blackjack strategy and a few less common, but equally crucial ones based on the S17 system:

Common Deviations in Blackjack

Below is a list of popular blackjack deviations and the basic strategy you’re deviating from:

  • Your total is 9, and the dealer has a 2. Hit (basic strategy)/double down with a true count of 1 or higher (deviation).
  • Your total is 10, and the dealer has an Ace. Hit (basic strategy)/double down with a true count of 4 or higher (deviation).
  • Your total is 11, and the dealer has an Ace. Double down (basic strategy)/hit with a true count of 1 or higher (deviation).
  • Your total is 12, and the dealer has a 2. Hit (basic strategy)/stand with a true count of 3 or better (deviation).
  • Your total is 12, and the dealer has a 3. Hit (basic strategy)/stand with a true count of 2 or better (deviation).
  • Your total is 12, and the dealer has a 4. Stand (basic strategy)/hit with a true count of 0 or lower (deviation).
  • Your total is 13, and the dealer has a 2. Stand (basic strategy)/hit with a true count of 1 or lower (deviation).
  • Your total is 15, and the dealer has a 10. Hit (basic strategy)/stand with a true count of 4 or higher (deviation)

Uncommon but Crucial Deviations

Below are some important but less common blackjack deviations you might need to employ during a game:

  • Your total is 8, and the dealer has a 6. Hit (basic strategy)/double down with a true count of 2 or higher (deviation).
  • Your total is 9, and the dealer has a 7. Hit (basic strategy)/double down with a true count of 3 or higher (deviation).
  • Your total is 10, and the dealer has a 10. Hit (basic strategy)/double down with a true count of 4 or higher (deviation).
  • Your total is soft 17, and the dealer has a 2. Hit (basic strategy)/double down with a true count of 1 or higher (deviation).
  • Your total is soft 19, and the dealer has a 4. Stand (basic strategy)/hit with a true count of 3 or higher (deviation).
  • Your total is soft 19, and the dealer has a 5. Stand (basic strategy)/hit with a true count of 1 or higher (deviation).
  • Your total is soft 19, and the dealer has a 6. Stand (basic strategy)/hit with a true count of 1 or higher (deviation).

One final deviation involves splitting a starting hand of 10 10. In most cases, you don’t split this hand. However, you can split under these three circumstances:

  • The dealer is showing a 4, and the true count is 6 or higher.
  • The dealer is showing a 5, and the true count is 5 or higher.
  • The dealer is showing a 6, and the true count is 4 or higher.

Key Blackjack Deviations Explained

Let’s delve into some of the most important blackjack deviations and explain why they’re necessary:

16 vs. 10: To Hit or Stand

You typically hit 16 against the dealer’s 10 because it stands a very small chance of winning a showdown. However, with a true count of 0 or higher, there are enough low cards left in the shoe to make hitting a profitable move.

12 vs. 3: Strategic Choices

12 vs. 3 is almost always a hit unless the true count is 2 or higher. That’s because the dealer is more likely to bust due to the fact that there are more high-value cards left in the shoe.

15 vs. 10: Optimal Moves

Standing on 15 against a dealer’s 10 seems like a crazy play, and in most situations, it is. If the game allows you to surrender, then you should take that option if the true count is 4 or higher. If you can’t surrender, it’s best to stand on 15 vs. 10 when the true count is 4 or higher. That’s because the dealer’s hidden card is likely to be low, requiring them to hit at least once more and risk going bust.

10 vs. 10: Doubling Down Decisions

Doubling down on 10 vs. 10 would be regarded as an overly aggressive play if you didn’t know how to count cards. However, if the true count is 4 or higher, you can double with a good chance you’ll hit another 10. Ideally, in this spot, you’ll have deviated from your standard bet size and made a larger opening bet, so you can really capitalize on the count.

Advanced Deviation Techniques

Blackjack deviations aren’t for the inexperienced player, so make sure you really understand their utility before you try them. If you’re confident you can make the right deviations at the right time, here are additional variables that can help you make better decisions:

Playing Deviations Based on True Count

All deviations in blackjack should be based on the true count. If you use a deviation chart, these symbols tell you what to do:

  • A + symbol indicates you should deviate if the true count is that number or higher, i.e. +3 means deviate if the count is 3 or higher.
  • A - symbol indicates you should deviate if the true count is that number or lower, i.e. -3 means deviate if the count is 3 or lower.

Adjusting for Penetration Levels

Penetration refers to the number of cards a dealer cuts off relative to those dealt. Put simply, it’s the number of cards dealt before a reshuffle. You need to factor this into your count because you get more value with better penetration, i.e. you want the dealer to only cut off a small number of cards, so you’ve got more to work with.

Deviations for Single Deck vs. Multiple Decks

In general, deviations in single-deck blackjack are the same as multi-deck. The only thing you have to account for in single-deck games is that running count is the true count. Get this right, along with everything else we’ve covered, and you’ll be well on your way to making the right blackjack deviations at the right times.

FAQ

What are blackjack deviations?

Blackjack deviations are theoretically profitable moves that go against basic strategy based on the true count. For example, basic strategy tells you to stand on 12 vs. a dealer’s 4. However, if the count is right, you can deviate from this move and hit.

What is the difference between H17 and S17 deviations?

H17 blackjack deviations are prescribed for games where the dealer must hit on soft 17. S17 blackjack deviations are prescribed for games where the dealer must stand on soft 17.

How do you calculate the standard deviation in blackjack?

Standard deviation is a measure of variation around an expected norm. The typical standard deviation for a blackjack player who bets the same amount per hand is 1.15. You can apply this to your bets in blackjack to determine your potential EV (Expected Value) by multiplying your bet average bet size by 1.15.

What is the true count in blackjack?

The true count in blackjack is the running count divided by the number of decks remaining in the shoe. This number gives you an accurate (true) representation of how many high vs. low-value cards are left in each of the remaining decks.

Learn more about blackjack in other guides: