What is 21+3 blackjack? This popular side bet can be placed alongside your initial bet in the casino classic. It mixes blackjack and three-card poker to offer some attractive odds.

How to play blackjack 21+3

In the 21+3 blackjack side bet you bet on whether the first two cards of your hand and the dealer’s face-up card combine to make one of the three-card poker hands below:

• Flush – Three cards in the same suit
• Straight – Three cards of consecutive values, such as 2-3-4. Aces can be high or low
• Three of a kind – Three cards of the same value/face card
• Straight flush – Three cards of consecutive values that are all in the same suit
• Suited three of a Kind – Three cards of the same value/face card and the same suit

You place the bet before your cards are dealt. Typically there will be a 21+3 box on the table in which you place your stake for the side bet. 

If your first two cards plus the dealer’s up-card combine to provide one of these five hands then you win your 21+3 blackjack bet. If not, you lose your side bet stake.

How much you win depends on which three-card hand you get, with each one paying different odds, more of which below.

21+3 blackjack odds

• 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

Odds shown are those used by Grosvenor Online Casinos and other operators may vary.

There are different 21+3 blackjack odds attached to the five different types of winning hands, which relate to the probability of players landing them.

It’s always advisable to double check the 21+3 blackjack odds at the particular land-based or online casino where you plan to try out the side bet. They can differ to some degree from one casino operator to another. 

For the purposes of this piece we’ve used the odds they work with at Grosvenor Casinos. Check out our Grosvenor Casinos review.