Blackjack Strategy: The Ultimate Guide to Online Blackjack

Blackjack is one of the most popular games in the casino. It's been played in various formats for hundreds of years and is a familiar game to lots. What makes it unique in comparison to most casino games is that you can apply strategy to each hand. Certain plays will return more money than others, and if you can implement even a basic strategy, then you're going to be able to reduce the house edge massively.

Strategy can be hard to grasp for some, but the game doesn't need to have a strategy applied to make it exciting. Once you understand the basic rules, it's still possible to make money; you just need a bit of luck.

Throughout this article, we want to take you through the basics of the game whilst pointing you in the right direction of our best blackjack sites. We've lots of articles on site that talk in-depth about some of these concepts and strategies, so we will also link to those where possible.

What is Blackjack?

Blackjack is a card game where you go head to head with the dealer to make the best score of up to 21. When you have a higher score than the dealer, then you win the hand. When you have a lower score, then you lose the hand.

Your cards have a numerical value that allows you to create your score. Here is how that works:

• Ace = 1 or 11
• Two = 2
• Three = 3
• Four = 4
• Five = 5
• Six = 6
• Seven = 7
• Eight = 8
• Nine = 9
• Ten = 10
• Jack = 10
• Queen = 10
• King = 10

You combine the value of each card to make your overall total. If you get 21 this is the best score you can get, but if you get even one number over 21, then your hand loses, regardless of what the dealer has.

How Do You Play Blackjack?

The action starts with the dealer. They will have at least one standard deck of 52 cards. Often games will have multiple decks, but this does not alter how the game or the rules would work.

A bet must be made by the player to signify they are in the hand. The bet amount cannot be changed once the deal starts and the action signifies to the dealer that the player is in the hand.

They will deal the player two cards face up. They will also deal themselves two cards, with one card being face up and one card being face down. Action falls on the player to act first. They can make several decisions here, which include:

• Hit – To take another card from the dealer for free. This can be done as many times as the player wishes until they go bust.
• Stand – This means the player does not want any more cards and is happy with their hand.
• Double Down – Here the player pays the price of their original bet to buy one more card. Any winnings will be paid on the cumulative amount of money in the pot. This is the only way that players can get more money into the pot for an active hand.
• Split – This allows the player to split their hand into two separate hands. They must match the original bet and then each hand works as a single bet.

Once the player has finished making their play, the action then moves to the dealer. The table rules determine how they then have to play their hand.

As a general rule, they will need to hit on scores of 16 or lower and stand on 17 or higher.

After betting is complete, the player's score is compared to the dealer's score. If the player has a higher score, then they win even money on their bet. If they have the same score, then this bet is a push, which means you don't win or lose and keep your stake. If they have a lower score than the dealer, then the player loses their stake.

If the player has a ten-value card with an Ace, this is called Blackjack. The dealer will instantly payout on this hand. Odds are usually 3:2.

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Understanding House Edge and How this Applies to Blackjack

All casino games are mathematically set up in the casino's favour. Each game comes with what is known as a house edge, and you must understand how this works and become comfortable with it.

One of the key things to note with house edge is that for pretty much every single bet, the casino will make money over a huge sample size. Lots of people who are new to casinos are shocked by this, but it's basics of how they make money.

Do not get too hung up on it!

The house edge works by making bets that are in the casino's favour. For example, an online slot might have a 97% RTP (Return To Player). It means that for every £1 staked, they return 97p to the player and they keep 3p.

A casinos edge in blackjack is one of the lowest that you can get. It ranges for each game type, but they can be as little as 1%.

The catch is that for this, you need to apply a basic casino strategy. The strategy is all based on cards you dealt and the cards that the dealer is dealt.

Applying this strategy decreases the house edge. You need to make the right calls every time for the house edge to remain low.

You're probably wondering why casinos are so keen to push a game that has such a low edge? Well, the reason is that most players don't apply this basic strategy and they play on "feel". When players do this, the house edge starts to massively increase as they aren't playing optimal in each position.

If you're new to blackjack or even casinos in general, this may seem like a lot to take in. In reality, it's pretty basic, so make sure you take the time to understand house edge and how in blackjack you can affect it, unlike the majority of other casino games.

The final thing to note here is that the house edge is taken over a large hand sample. We're talking millions of hands and combinations dealt.

What happens in the short term is known as variance. This allows the player to win sometimes and keeps them coming back. Blackjack may have a house edge of 1% or under, but this does not mean you are guaranteed to break even or slightly worse over 50, 100 or even 1,000 hands.

Why is blackjack so popular?

One of the main reasons is that the game is relatively easy to pick up. It's one of those that lots of us have played in some form at school or with family members, even if it's not for money.

The concept of the game is simple. You're playing against the dealer to get the highest score of 21 or under. You use the cards as a numerical value and then decided to "improve" (hit) or not (stick).

A more advanced answer to this would be the ability to massively reduce the house edge and apply a strategy to your bets. The concept of the game is easy, but taking it to the next level is more laborious, which lots of players like.

Some strategies can even include things like card counting, which is not illegal, but almost impossible online. These are highly advanced mathematical processes that take years if not decades to master. Only a few can successfully do it.

Compare all this to the fixed, relatively formulaic process of playing online slots, and you can start to see why it's such a popular game.

How have Online Casinos Affected Blackjack?

Online play has undoubtedly brought the game to the masses. Online casinos love the game and players can access an alternative to slots and roulette, playing something that they are likely going to recognise.

We've seen a considerable increase in the strategy for the game since appearing online as well. You could have gone to a casino in the eighties, and there might have been 1 in 100 people who had an idea of basic blackjack strategy.

Compare that to online, and while we don't have figures, we would guess that around 50% of players are using blackjack handcarts for their play. You're sat here right now reading about strategy, which would suggest that more people like you are doing the same.

The explosion of people playing blackjack "perfectly" online is not one that will bother the casinos too much. The volume will mean that they can get lots more people losing 1% then they would at 10% and make more money from it.

Players lose less, and casinos make more, everyone is a winner.

Online has also allowed the game to adapt to other variations and formats. These have tweaks on the rules and they, in turn, change up the game slightly. It keeps things feeling fresh and allows players to pick their games based around how they want to play blackjack, rather than just one standard process.

Different Variations of Online Blackjack and House Edge

Lots of the games that you see online come from different developers. They may be labelled the same, but they could have a different house edge applied to each game.

For example, you may have two forms of European Blackjack, made by two game developers, but one has a house edge of 1% and the other a house edge of 2%. Just because they have the same name, don't assume they have the same house edge.

As a casino guide, we've listed below the games and how they might differ. We've taken games from several different developers and then taken the average here.

As you can see, the range of the house edge is significant, from 0.17% up to 1.30%. The shrewd punters amongst you should be looking to target Blackjack Switch and avoiding Super Fun 21.

Basic Strategy and Playing Style

The term "basic" is often branded when we talk about blackjack strategy in general, but the fact of the matter is that there is only one optimal strategy that can be applied to each game.

Your play will be mathematically determined prior to any cards that have been dealt. Every possible scenario will have been taken into consideration, so there is always a play that will make you the most money from that hand.

One of the key things to note here is that your strategy will need to adjust based on the game that you are playing. For example, in a typical American style where the dealer stands on soft 17, your play when you have soft 18 against a dealers Ace would be to stand. But if the game rules were for the dealer to hit in this scenario, mathematically the play would be to hit.

We have lots on site already about blackjack strategy and how you can apply it to your game, specifically looking at individual hands and scenarios.

Blackjack Myths

As you start to work out the processes for each game, you begin to question why things happen. This is a good thing!

There's an awful lot of bad advice surrounding blackjack, and there are several myths that we need to dispel. We've created an article that goes deep into each of these myths, but for this article, we just wanted to give an overview. You can check the full article out here.

• Get as close to 21 as possible – This is not the aim of the game. You need to beat the dealer, and it doesn't matter if you have 3 or 21 as your score.
• Other players can influence your game – Poor strategies can help you as often as they can hinder you. You cant affect the order or randomness of cards as they are already shuffled.
• A win is "due" – When dealers go on crazy winning streaks, players think that they should have more chance of winning to even things out. Not true. Each hand starts with the same mathematical edge.
• Always assume 10 in the hole for the dealer – 10's account for 31% of the deck, meaning it's more likely there is not a 10 in the hole for the dealer.
• Take insurance against an ace – Long term you are mathematically better not taking insurance against a dealer's Ace.
• Always split tens – 20 is the second-best possible hand going. If you split, there is a strong chance you get a dealt weakening hand and are now in an awful spot.
• Card counting is illegal – Nope. It's just tough and impossible online.
• Never go broke – A theory that people have is to stay in every hand and hope the dealer goes broke. This means standing on any card of 12 or higher. This is mathematically a losing play long term.

Doubling Down

Doubling down is one of the most critical bets that you can make in blackjack. It's the only time (aside from splitting) where you can increase the amount of money that you have in the middle.

It's so vital that it plays a considerable part in house edge and if you fail to make the right decisions when you double down, you lose those tiny house edges and put the ball firmly back in the casino's court.

As a quick refresh, doubling down is where you can buy your next card. You need to put in the same amount as your original stake, and you get one more extra card. After that card has been dealt, that is the end of your play.

When doubling down, you need to take note of the card the dealer has. These are split into soft and hard hands.

Hard Hands

This is where you should double down with hard hands. Hard hands are ones that do not include an Ace. Scenarios include:

• Hard 9 against the dealer's low card (3-6)
• Hard 10 and 11 against any lower dealer card

Soft Hands

These are where you should double down with soft hands. A soft hand will include an Ace to essentially make two possible combinations given that an Ace can count as 1 or 11.

• Soft 15 to 18 against dealer's low cards

As we mentioned earlier, table rules will come into play again here for doubling down. Make sure you note what they are and then how this will adjust accordingly. Hand charts will signify when you need to play these hands based on the table rules.

High Stakes and VIP Players

In theory, your blackjack strategy should not change whether you are betting £1 per hand or £10,000 per hand. The numbers bare no reflection on the amount of money you have in front of you, so try and make sure this does not affect your game.

If you are playing high stakes, then there are things you can do to make your time a little more worthwhile.

Online you should be contacting the casino before you play. They are likely going to give you a bonus or rewards for playing higher stakes. You will be able to rack up points very quickly and get something for nothing (assuming you were going to play these games anyway).

If you happen to play at casinos which form part of the Casino Rewards program, there is a unified point system in place. 

You need to make sure that you have your game plan tied down. You need to know the table rules, and you need to know how much you are looking to bet. The heart takes over from head all too often, especially if you aren't comfortable with those stakes, so make sure this does not happen.

Finally, find the game that takes the biggest bets with the lowest house edge. You may have to compromise here a little depending on just how high the stakes you want to play are but shop around as there are dozens of different game formats from a multitude of different game developers. If one casino doesn't offer what you need, there will be another dozen lining up to do just that.

Blackjack’s Hand Signals

Hand signals are an important part of blackjack. It is an aspect of the game that beginners often don't understand and are intimidated by. Getting hand signals wrong can result in losing games and looking foolish in front of other casino players. So it's best to learn your hand signals before heading to the tables. Keep in mind that there's a difference in signals when you’re playing face up or face down cards.

Face Up

Stand – Wave your hand from left to right over the cards (just the hand, don’t move your arm).

Hit – Either tap the table or point at your cards.

Double Down – One of blackjack’s most exciting moves, this is when you double your bet during a hand. To add this second bet with a hand signal, simply place your wager next to the first pile of chips and hold one finger to double the bet.

Split – A split is when a player can divide two cards of equal value into two separate hands. Like the double bet, you can signal a split by holding up, or pointing at the cards with two fingers in the V symbol after wagering next to the original bet.

(Note: When playing face up, you should not touch the cards during the game)

Face Down

Stand – Make a stand by sliding your cards underneath your chips. The trick is to be as elegant as possible without moving the chips. It may take some practice, but once you get it right, you've mastered one of the smoothest gestures in blackjack.

Hit – Run your index finger gently across the game table in a side motion.

Double Down – Add a second bet by doubling the chips and holding up one finger.

Split – Place more chips next to the original pile and hold up two fingers.

Blackjack Insurance

One of the easiest blackjack wagers is insurance. Don’t worry, it is not the monthly car and home insurance you are probably used to. Blackjack insurance is a betting option that protects your original wager. Still, there are some caveats.

Perhaps the easiest way to comprehend insurance is by knowing the player always bets on the dealer holding a potential blackjack hand (10 value card and an ace).

On blackjack tables, if the dealer holds an ace before showing the second card, the table can offer a side-bet. This is the blackjack insurance wager. Not all casino blackjack tables offer this bet, but most do. You don't have to worry about asking because the casinos that offer insurance make it clear that it's available.

It's important to note that blackjack insurance is a separate wager that is independent of the primary bet. It is a side-bet that comes with odds of 2:1. Whether it is worth taking a blackjack insurance bet depends on the cards you and the dealer have. Either way, it's an interesting betting option to have.

Blackjack’s Odds

Many casino players say that Blackjack is the game with the best odds of winning. Firstly the house edge, which is the casino's statistical advantage built into the game, is lower in blackjack than most casino games. The house edge for blackjack is around 1%, and if you follow a yielding betting strategy, it can be 0.05% and even lower.

But to get these great odds, you'll have to know what you’re doing. Would you hit 12 against a dealer showing 2? (The answer is yes). When do you split 4s? (Yes, when the dealer is showing 5 or 6). When do you split 8s? (Always.) There is a chance for great odds at the blackjack table. But to get these top odds, you will need to build a strategy and memorise decisions like these.

Some people ask if their chances of winning are affected by other players sitting at the blackjack table. The simple answer is no. It makes no difference how many players join the game. So another point in favour of blackjack odds is the fact that it's always you against the dealer.

Blackjack’s Side Bets

Side bets are extra bets you can place during a normal hand of blackjack. These wagers are unrelated to the original bet. They involve making predictions on what cards you or the dealer will get.

Below are the side bets available in blackjack:

Insurance – As we’ve already discussed blackjack insurance above, it's the most common side bet available during a game. It is offered when the dealer has an ace.

Perfect Pairs – While insurance is based on the dealer’s cards, perfect pairs are based on the player's cards. It pays out two of a kind for the following combinations:

• Mixed pair (two cards of the same value of any suit or colour) – odds of 5:1
• Coloured pair (two cards of the same value and same colour) – odds of 12:1
• Perfect pair (two equal value cards of the same colour) – odds of 25:1 Returns on perfect pair side bets depend on what the casino is offering at the pay tables. It will also be affected by the house edge and the number of decks. A normal range for perfect pair wagers is between 2% and 10%.

21+ 3 – With this side bet, you base your wager on your two cards and the dealer's face-up card.

• Flush (all cards of the same suit) – odds of 5:1
• Straight (consecutive number cards) – odds of 10:1
• Three of a kind (Any three same value cards of any suit) – odds of 30:1
• Straight Flush (consecutive number cards of the same suit) – odds of 40:1
• Suited triple (a three of a kind of the same card) – odds of 100:1

House edge for the 21+3 bets depends on the number of decks in use during the blackjack game. Some of the combinations above can only happen with multiple decks. Games with four decks have a house edge of 8.78%, five decks are 7.81%, six decks 7.14%, and seven decks 6.29%.

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Betting Systems

Blackjack systems are betting and gameplay strategies designed to give players more chances to beat the house edge. Below are some of the most famous blackjack betting systems:

Edward Thorp System

Edward O. Thorp is considered by many the originator of modern blackjack systems. He created a math model for beating the house. In his 1960s book Beat the Dealer, Thorp claimed that his blackjack model could apply in money management and investment.

Visiting Las Vegas in the 1950s, the mathematics PhD found that blackjack does not match the laws of the widely-accepted probability theory. Therefore Thorp believed he could create a system that would allow him to actively attack the dealer and make a profit.

And so was born Thorp’s Blackjack Basic Strategy Chart. It remains to this day a valuable tool for guiding blackjack players through their decisions throughout the game. Thorp explains in his book and chart combinations when players should hit, stand, split, or double down.

Thorp shows that gambling on blackjack happens within a closed system, and the outcome is determined by a finite number of factors. He bases these strategies on the card the dealer has facing up, the two cards the player holds, and finally the remaining cards in the decks.

1-3-2-6 Betting System

The 1-2-3-6 betting system is one of the most elegant gambling strategies in the world. Many gamblers say that its beauty is in its simplicity. Perhaps the best thing about this method is how easy it is to learn and implement. It can also be an instantly rewarding system if you manage to win your first two bets.

Admittedly, the 1-3-2-6 System is best for Baccarat and Roulette. But it can also be used in blackjack. Players must define a stake that will be their betting unit. This single unit functions across the sequence and must be increased in multiples (for example, 2x the unit bet). Each time you win a hand, you must increase the unit stake.

One of the benefits of the 1-3-2-6 system is that you’re never putting much of your bankroll at risk. If you suffer a loss, simply re-start the sequence or stop using the system. You only need to increase your wager (unit multipliers) when you win.

Oscar’s Grind Betting System

Oscar’s Grind betting system is easy to implement. But it is considered a high-risk, high-reward betting strategy. It is most commonly used with even-money bets and the player should typically have a winning goal in mind.

For players who want a simple betting system that does not escalate wagers quickly and doesn’t demand higher bets when losing, Oscar’s Grind is a solid choice. It’s a system for players who don’t mind dealing with long winning and losing streaks.

Below is how the Oscar’s Grind betting system is used:

Define your winning goal.

Decide on a “unit size”, which is the value of your individual bets.

Make a one-unit bet.

If the bet results in a win, increase the bet by one unit.

Keep adding units for every winning bet or until you reach your winning goal.

Any loss within the sequence results in the system ending or restarting.

Fibonacci Betting System

Betting systems are all meant to give players large chances of winning. The Fibonacci system fulfils this criterion because it typically guarantees a winning session. However, the major caveat of this strategy is that losses can be huge if you are out of luck. That’s because the Fibonacci system dictates that you should increase bets when you lose.

As its name suggests, this strategy uses Fibonacci numbers which is a sequence used in mathematics and science. We won't go into detail about the number complexity here, but what is important is to understand is the sequence itself.

The first two Fibonacci numbers in the sequence are 1 and 1. Following those numbers, each subsequent digit is the sum of the previous two numbers (so the third number would be 2, the sum of 1 and 1). These numbers are denoted as F(n), which is the notation for Fibonacci Numbers.

The first 25 numbers in a Fibonacci sequence are: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025.

Implementing the system, you will need to:

• Increase your betting units by one number up the Fibonacci scale every time you lose.
• Decrease your betting units by two numbers down the Fibonacci scale every time you win.

Paroli Betting System

The Paroli system is a progressive betting strategy. It can be easily defined as a doubling betting method. This means that you double your wager after a win, up to three consecutive wins. Gamblers have been using the Paroli system for hundreds of years and it remains among the most popular betting systems.

While it uses an even double-wager strategy, the Paroli betting system can be modified to work with blackjack. Because it relies on three consecutive wins, the Paroli is a risky system. That said, it is possible to hedge your bets by not placing too much on the initial wager.

To begin the Paroli betting system, wager a single unit. If this bet loses, start again with a single unit wager. You must keep placing the same bet until you win, and then you double the initial wager to two units. Losing this bet takes you back to the beginning. However, if this second two-unit bet wins, you double the next wager again to four times the original bet (4 units).

This is the final bet of the sequence whether you win or lose. By the end of the progression, you will either have a net loss or be back to placing a single unit wager. Or you will have made seven units from that initial, first-unit bet.

Labouchere Betting System

Created by roulette player Henry Labouchere in the 1800s, it was at first developed for roulette. Since its inception, the Labouchere betting system has been modified for blackjack and even sports betting.

The Labouchere betting strategy is interesting. But it is a complicated system that probably won't suit beginners. Amongst more experienced blackjack players, this system is popular despite its complexities. It is also known as the Cancellation System, Split Martingale, and American Progression.

Labouchere is known as a negative progression system. This means that you increase your bet after each loss. Although this seems counter-intuitive, the idea is to eventually recover losses. The problem is whether you run out of bankroll before losses can be recovered.

Below, is how you implement the Labouchere strategy:

• To start with the Labouchere system, write down a sequence of numbers. For example 1-2-3. The potential profit of each betting cycle of this system is the total value of the numbers you chose. In this case, it's 6.
• Each time you bet, the stake should equal the sum of the first and last number in the sequence, in this case, 4 (1+3).
• If you win a wager, you remove the first and last number from the sequence. In this case, you remain with 2.
• If you lose a wager, you add the stake amount at the end of the sequence. So losing your first wager, in this case, will be adding a 4.
• You will do this routine after every wager. For each subsequent wager, you will bet the combined amount of the first and last numbers on your list.

Parlay Betting System

Widely common in sports betting, Parlay betting is also used at casino table games including blackjack. Parlay betting is a positive-progression system that calls to increase bets after a winning hand and decrease bets after a losing one.

For example, if you bet £10 and won a hand of blackjack (paying 1/1, or £10), you would then bet £20 on your next hand (£10 win + £10 your initial stake). If you win again, you will bet £40 on the following hand (£20 win + £20 returned stake) and so on. If you lose, you will start with your initial stake again (£10 in this case).

Under the Parlay betting system, you are trying to build profits and even maintain your bankroll. That’s because you will only wager the original unit and whatever profits you make. In other words, you won’t be dipping into your funds for additional bets unless you lose. Like all betting systems, the success of the sequence depends entirely on whether you can win your blackjack hands.

Another good thing about the Parlay system is its versatility. It functions across any type of game and does not have any limits on the amount you can wager. This strategy works for any bet amount you want to make, you just keep re-betting any winnings you make until you reach your goal.

D'Alembert Betting System

French mathematician Jean-Baptiste le Rond d’Alembert developed the system when he became a victim of the gambler’s fallacy. It was an error in judgement, where he believed the probability of a win or a loss has changed. Where In reality, the game has remained the same and the chances of success or failure unchanged. After making this mistake, D’Alembert decided to create a system to protect against the gamblers' fallacies. It can be used on any wager and is based on the concept of winning as many even-money bets as you lose.

Next to the Martingale system, the D’Alembert betting system is probably the most popular in the gambling community. Part of its success can be traced to how simple the system is to use effectively. It is a negative progression system that means you must increase your stake after each losing wager and decrease after a winning wager.

Beginners typically like the D’Alembert because it increases wagers slowly. It does not put as much pressure on bankroll as other systems. Stakes are not likely to explode using this strategy, which is helpful. However, the reverse of that benefit is any losses can also take longer to recoup. So although you can make a loss, it won’t be too big. Still, it may take time to recover it.

Here’s how to play the D’Alembert betting system:

• Start with a base unit (the initial wager).
• Stake a single unit.
• Increase the stake after a loss by a single unit.
• Decrease stakes by a unit after every winning bet.

Card Counting

Card counting can decrease the house edge to 0.28%, but in land-based casino Blackjack, this behaviour will get you thrown out while computer casino software in the online world makes counting hard to do. So, it is best to learn some of the simpler, more transparent tactical moves that can seriously benefit you and your chip stack.