21+3 Blackjack Side Bet: Rules, Odds, and How to Play the Bet

21+3 is one of the most popular and fun blackjack variations that’s played as a side bet in standard blackjack. It can be placed alongside your initial bet and it offers the biggest odds in this popular casino game.

But how is the 21+3 blackjack side bet played exactly, what are the rules and payouts, and most importantly, can you beat this game? If you want to find out and become adept at blackjack, keep reading!

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What is 21+3 Blackjack?

21+3 blackjack is a popular variation of blackjack that’s played as a side bet in a regular blackjack game. Some consider it a mix between blackjack and poker, as the main point of it is to find combinations of cards similar to poker hands (e.g., flush, straight, etc.).

In this variation of blackjack, you place the bet before your cards are dealt, and if your first two cards and the dealer’s up-card make up one of the winning hands, you win your side bet stake. Check out the table below to see the possible winning hands in 21+3 blackjack:

FlushThree cards of the same suit.
StraightThree consecutive cards, e.g., 3-4-5
Three of a kindThree cards of the same value
Straight flushThree consecutive cards of the same suit
Suited three of a kindThree cards of the same value and in the same suit.

21+3 Blackjack Side Bet Rules

21+3 blackjack side bets strategy is beginner-friendly and has fairly simple rules:

  • The game is generally played with 6 decks of cards.
  • The dealer stands on all 17s.
  • You can split up to 2 blackjack hands, even the Aces.
  • You can double down on 9, 10, and 11.
  • You can also double down after a split.
  • When you double down, you receive only one additional card.

Even though the standard blackjack pays 3:2, you have numerous ways to win at this popular side bet. The payout depends on the combination you receive from the dealer’s up-card and your two cards. For more details, check out the table below:

Three of a Kind33/1
Straight Flush35/1
Suited Three of a Kind100/1

How to Play the 21+3 Side Bet in Blackjack

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Before the cards are dealt, you have two choices as to where you can place your bet. The first is the mandatory blackjack bet, and the second is the optional 21+3 bet. This optional bet cannot be played by itself and must follow the mandatory bet. 

Usually, a blackjack table will have a 21+3 box in which you can place the stake for your wager after placing the blackjack bet. If your two cards, combined with the dealer’s up-card provide one of the winning combinations, the 21+3 side will be paid first and the hand will continue as a normal blackjack hand.

The amount you’ll win depends on the hand you get. That being said, we’ll go over the possible combinations in 21+3 blackjack in the section below, to help you get familiar with the payouts and probabilities.

Three of a Kind

In 21+3 blackjack, you can get a Three of a Kind, which is a hand that consists of three cards of the same value. If those three cards also belong to the same suit, you get a Suited Three of a Kind, which pays the most (100).

If you’re playing the standard variation of blackjack with 6 decks of cards, the probability of you getting a Three of a Kind is 0.5%, whereas it’s 0.021% for a Suited Three of a Kind.


A Flush is the lowest paying card combination in blackjack 21+3, and it consists of three cards of the same suit. It pays 5, and you have a probability of 5.84% to land this hand.


If your initial two cards and the dealer’s up-card are of consecutive values, for example, 6, 7, and 8, you get a Straight. This combination pays 10 and has a probability of 3.1%.

Straight Flush

A Straight Flush is the strongest hand in poker and the rarest combination you can get in 21+3 blackjack. It calls for three cards of consecutive values that belong to the same suit.

In a standard blackjack game, a Straight Flush pays 30 and has a probability of 0.21%.

Odds of 21+3 Blackjack Side Bet

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The house edge of the 21+3 blackjack mostly depends on the casino’s rules and the variation of the game you’re playing. When compared to other side bets, the standard house edge of 21+3 blackjack is more than reasonable, as it can range anywhere from 2.78% to 13.39%.

The percentage return to the player (RTP) in this side bet is 95.38%, and on top of that, the wager gives you multiple options to win. Here’s a detailed overview of the statistics of 21+3 blackjack:

HandPayoutOdds# of CombinationsProbability
Three of a Kind33/11:199252720.5%
Straight Flush35/11:499103680.21%
Suited Three of a Kind100/11:499910400.021%

Can you Beat the 21+3 Blackjack Side Bet?

Now that you’re familiar with 21+3 blackjack, you’re probably wondering whether you can beat this game or not.

According to Eliot Jacobson, a professional gambler, card counter, and mathematician, the game can be beaten but with great difficulty and low returns.

To beat 21+3 blackjack, you need to target flushes by finding imbalances in the suits’ favors. This requires you to keep track of the number of cards in each remaining suit in the shoe, and then place big bets only when you think you have a high chance of getting a flush.

As this is incredibly difficult to accomplish on your own, you would require a team of counters, each tracking a single suit of cards. But, considering the effort you need to put into this, trying to beat 21+3 blackjack is just not worth it.

Key Takeaways

Overall, 21+3 blackjack is a fun side bet that will always remain a must-try if you’re playing this casino classic. It’s simple, offers big payouts, and brings a whole new dynamic to blackjack.

To sum it up, here are the main points that we covered:

  • The 21+3 blackjack side bets strategy requires you to make up one of the winning three-card hands using two of your cards and the dealer’s up-card.
  • 21+3 blackjack is played with 6 decks of cards.
  • The payout in 21+3 blackjack depends on the hand combination you have.
  • To win in 21+3 blackjack, you have to get one of the five winning hands: Flush, Straight, Three of a Kind, Straight Flush, or Suited Three of a Kind.
  • Although you can theoretically beat 21+3 blackjack, it is quite difficult and not worth the effort.

21+3 Blackjack Side Bet FAQ

#1. What is the 21+3 bet in blackjack?

The 21+3 bet in blackjack is a side bet that you place on whether your two cards and the dealer’s up-card make up one of the winning three-card hands, such as:

  • Flush–Three cards in the same suit.
  • Straight–Three consecutive cards, for example, 3, 4, and 5.
  • Three of a Kind–Three cards of the same value.
  • Straight Flush–Three consecutive cards in the same suit.
  • Suited Three of a Kind–Three cards of the same value and in the same suit.

#2. What are the payouts for 21+3 blackjack?

The 21+3 blackjack payouts depend on the hand that you have and are as follows:

  • Flush–5/1
  • Straight–10/1
  • Three of a Kind–33/1
  • Straight Flush–35/1
  • Suited Three of a Kind–100/1

#3. What does 21+3 mean in blackjack?

In 21+3 blackjack, 21 is the total point score that you need to get or come as close to as possible to with your combination of cards. On the other hand, 3 stands for the three-card combination you bet on as a side bet.

#4. Is the 21+3 bet standard in all blackjack games?

Yes, 21+3 is one of the standard bets in all blackjack games, but it is the casino that decides whether you can place this side bet or not. If the casino allows it, there will usually be a dedicated 21+3 side bet box placed on the table.

#5. Where can I play the 21+3 bet in blackjack?

The European variation of blackjack is the variation that most commonly features the 21+3 bet and can be found in numerous casinos all over Europe. You can also play Vegas Ace, which is a blackjack variation that you can play in Las Vegas. Most online casinos also feature 21+3 blackjack.

Rhonda Wilson

Blackjack Expert

Having joined our team in 2021, Rhonda Wilson is our newest team member. She discovered her interest in blackjack in 2006 and has written blackjack reviews for several gambling sites.