How to play 21+3 blackjack side bet for beginners

Blackjack is a rather simple game, and casinos worldwide improved it by developing new versions. One such game is 21+3 blackjack, popular in every casino in the United States and the United Kingdom. You can now play it at online casinos like CAT368, where you can bet and win real cash prizes from the comfort of your home.

What is 21+3 in blackjack?

21+3 blackjack is a table game that uses a standard stack of 1 to 8 decks per round. It follows the same gambling rules you know and loves while also introducing elements from a three-card poker game as a side bet. What is 21+3 in blackjack? The numbers refer to the combination between the standard blackjack rules (21) and the aforementioned 3-card poker (+3). 

How does 21+3 work in blackjack?

You can simplify the concept of 21+3 blackjack by dividing it into two separate games with independent bets from each other. The first element is the name it took which is ‘blackjack’, where you build your hand as valuable as possible compared to the house. 

Three-card poker is built on top of the existing rules, which takes the first three cards to create a winning combination. This consists of the two starting cards from the player’s hand and one up card from the dealer. The three-card poker side bet resolves as soon as the cards are dealt, then proceeds to play as normal blackjack.

21+3 blackjack rules

Players can play 21 plus 3 blackjack the same way as they would its standard version. If you’re unfamiliar with the game, then this is the standard process from start to finish:

  1. Place the main bet (mandatory to play a hand)
  2. Place a side bet for the +3 (optional after the main bet)
  3. The dealer puts two cards each of two hands, yours and the house’s
    1. Choose between one of these actions
      • Double down – Double the ante, draw a card, then stand simultaneously
        • Only available at the start of the game
      • Split – Separate your pair of starting cards into two separate hands
        • Only available if the starting hand is a pair of two equal ranks
      • Hit – Draw a card to increase the value of your hand
      • Stand – Stop at the current value of your hand
  4. The turn passes over to the dealer once every player stands, or the hand ends in a bust
  5. The dealer keeps hitting until the house reaches a minimum of 17 or ends in a bust
  6. The game ends, and bets are resolved after the dealer’s turn

The game objective is to have a hand worth more than the house without going over 21. This is how you win your bet in online casinos and take home payouts in the game. Reaching past 21 is called a ‘bust’, a state of automatic loss unless the dealer (or croupier in some houses) ends in the same situation. 

Points are assigned to each card equal to the face value of their rank. Numbered cards equal their respective numbers, while Jack, Queen, and King are each equal to 10. Ace is 11 by default but becomes one once the total reaches beyond 21, saving your hand from a bust. 


How to play 21 plus 3 blackjack

21+3 blackjack rules follow blackjack for the most part, but the three-card poker side bet adds another layer to learn. One key difference is that the payout is determined by the rank of the poker hand multiplied by the wager. 

It revolves around the concept of the ‘winning hand’, a poker-exclusive system that determines the hand’s value based on the combination of cards. Here’s a table of possible combinations arranged in ascending order:

Suited Three of a KindA Three of a Kind, but all cards have the same suit.
Straight FlushA combination of both Straight and Flush
Three of a KindAll three cards have the same rank (number or letter)
StraightEach card is only one rank apart, forming a sequence.
FlushAll three cards have the same suit (shape and colour)
PairTwo out of three cards have the same rank
High CardThere is no combination

21+3 blackjack odds

Your odds are different for each winning hand in the blackjack side bet 21+3 based on all the ranks and suits available in a deck. 21+3 blackjack shares the same 42.22% chance of winning as regular blackjack because little to no part of its rules are changed, with only a 2% house edge. The plus 3 part of the game adds extra intrigue for players.

21+3 blackjack payouts

The winnings you can get from each winning hand reflect their chance of happening per round. Here’s the standard paytable of 21+3 blackjack payouts.

  • Flush pays 5:1
  • Straight pays 10:1
  • Three of a Kind pays 30:1
  • Straight Flush pays 40:1
  • Suited Three of a Kind pays 100:1

The payouts start at Flush because it is the cutoff in the winning hand hierarchy. Pair and High Card don’t count as wins. 

Play blackjack 21 plus 3 online at CAT368

You can play 21+3 blackjack at CAT368, the best online casino in Vietnam. It supports various currencies for betting, fun deposit bonuses every week and plenty of giveaways for loyal customers. 

There will be several tables for you to choose from, and all of them feature the same 21+3 blackjack odds for a consistent experience. If you want to take a break from online blackjack, you should try other casino games at CAT368. 


21+3 blackjack is a combination of blackjack and three-card poker. This is a surprisingly effective tandem that garnered popularity in luxury brick-and-mortar casinos. Now, you can experience its fun mechanics online at CAT368. Remember to claim some bonus rewards to boost your chances of winning and improve your overall experience.


What is blackjack in 21 with 3 cards?

Blackjack refers to getting an Ace and any 10-valued card (10, Jack, Queen, or King) for a total of 21 with just two cards. This is also called a ‘natural’ and pays 2:1 or 3:2, depending on the table. Getting a sum of 21 through hits or double downs doesn’t count as ‘blackjack’.  

Should I play the 21+3 side bet?

Yes. The 21+3 side bet is the mechanic that made it popular. It still plays like a standard blackjack game, but the 21+3 side bet adds a lucrative opportunity to win extra money. 

How to win a straight flush in 21+3 blackjack?

You win a straight flush if your starting hand and the dealer’s up card form a sequence and are all wearing the same suit. 

How to win 21+3 blackjack?

You win the 21+3 blackjack main bet by ending the round with a hand more valuable than the dealer without going over 21. The side bet is won if the first three cards on the table form a flush or higher winning hand in three-card poker.

Where to play blackjack online?

You can play blackjack at CAT368, the best online casino in Vietnam. There are plenty of blackjack titles for you to choose from because they are partnered with many of the best online casino providers.