The 21+3 Blackjack Side Bet

By Aviva

Updated 26 Nov, 2025

The 21+3 Blackjack Side Bet

A disclaimer before we start: The House will always have the edge. Players should never try to recover losses by gambling more. The outcome of the games is always entirely based on luck.

Blackjack is already one of the world’s most popular card games, but when you throw in a few Blackjack side bets, you add a whole new dimension to the experience! One of the most popular of these is the 21+3 Blackjack bet.

Contrary to what that numerical name might suggest, there’s no need for groan-inducing maths here (phew!). 21+3 simply refers to the game itself and the cards that are involved. In fact, this little twist of a bet actually focuses on another very popular card game entirely!

Brush up on the Blackjack basics first if you need to, then let’s take a closer look at this unique little side bet.

What is the 21+3 Blackjack side bet?

21+3 Blackjack is a common additional bet that can be found at many virtual Blackjack tables, but is usually a feature of live dealer games using multiple decks (though not always). The 21 3 blackjack rules are simple: your hole cards and the dealer’s up card together must make a three card poker hand of flush or better.

21+3 Blackjack side bet

If you enjoy playing Blackjack online for fun, the 21+3 bet can enhance your enjoyment of the game even further by introducing a whole new element and opportunity to beat the dealer – using one of their own cards, no less!

21+3 Blackjack Winning Hands

Not all poker hands win with the 21+3 Blackjack bet. Some standard poker hands can’t be made with just three cards (eg. full house), while low value hands such as a pair or two pair don’t count.

Here’s a look at the paying 21+3 Blackjack hands, from lowest to highest value:

Poker hand 

Description 

Flush 

Three cards of the same suit, eg. 3s, 5s, Js 

Straight 

Three cards of consecutive value, eg. 3, 4, 5 

Three of a Kind 

Three cards of the same value, eg. 3, 3, 3 

Straight Flush 

Three suited cards of consecutive value, eg. 3s, 4s, 5s 

Suited Trips 

Three suited cards of the same value, eg. 3s, 3s, 3s 

How to place the 21+3 side bet

How to place the 21+3 side bet

As you can see in the image above, each of the five main Blackjack betting positions has some smaller text around it. To the left is Perfect Pairs, while 21+3 sits to the right.

The 21+3 Blackjack bet cannot be placed on its own, so it’s not a standalone bet. You have to place a bet on the main Blackjack game first, then you can bet on 21+3.

Once you’ve selected your chip value and placed a Blackjack bet, do the same for the 21+3 bet, then you can click the Deal button to start the round.

The 21+3 bet is settled as soon as your two hole cards and the dealer’s cards have been dealt.

21+3 Blackjack Payouts

21+3 Blackjack payouts can be pretty substantial, depending on the poker hand you get. If you’re lucky enough to land a poker hand of flush or better with your two hole cards and the dealer’s up card, you can expect to get a payout of between 5/1 and 100/1 as follows:

Poker hand 

Payout 

Flush 

5/1 

Straight 

10/1 

Three of a Kind 

30/1 

Straight Flush 

40/1 

Suited Trips 

100/1 

Chances of Winning 21+3 Blackjack

To get an idea of your actual chances of winning, let’s take a look at the 21+3 Blackjack odds. If you’re already a fan of learning how to win at Blackjack, you likely already know that payout odds are not the same as probabilities!

Here are the probabilities of landing each of the 21+3 Blackjack bets:

Poker hand 

Probability 

Flush 

5.9% 

Straight 

3.1% 

Three of a Kind 

0.5% 

Straight Flush 

0.2% 

Suited Trips 

0.02% 

Experts will tell you that you can actually get a very slight edge on this bet by counting cards or using a Blackjack counter. However, most online games employ card shuffling between rounds, which obliterates any possible advantage that counting cards may have given you.

My 21+3 Blackjack experience

So there’s all the theoretical stuff surrounding the 21+3 Blackjack bet, but what does it actually look like in practice?

To illustrate the slim probabilities of landing this bet, I had planned to play as many rounds of Blackjack as needed until I triggered a 21+3 win.

But, of course, ‘the best laid plans’ and all that… Turns out, by some bizarre fluke, I landed a 21+3 flush win on my first hand – typical! 🙄😅

In all seriousness, the likelihood of landing a 21+3 win in general is pretty slim, as you can see from our little probabilities table above. In reality, you could play many rounds and still not land a 21+3 win. If you want to play responsibly, the best 21+3 Blackjack strategy is to bet sparingly, with just a small amount, and only as a bit of fun.

Again, it is best to remember that the House will always have the edge. Players should never try to recover losses by gambling more. The outcome of the games is always entirely based on luck.

FAQs 

What is the 21+3 Blackjack bet?

The 21+3 Blackjack bet is an additional bet that pays if your two hole cards and the dealer’s up card together create a poker hand of flush or better.

How does 21+3 work?

After you’ve placed your main Blackjack bet, you can place chips on the 21+3 bet next to your main bet. Once the cards have been dealt, your two hole cards and the dealer’s up card is assessed to see if together they make up a paying poker hand. If so, the bet is settled immediately.

What are the 21+3 Blackjack payouts?

21+3 Blackjack payouts vary depending on the value of the poker hand you’ve landed. A 21+3 Blackjack win can return between 5/1 for a flush and 100/1 for suited trips.

Is it worth playing 21+3 Blackjack?

Not really, no, but it’s fun to try! The likelihood of landing a 21+3 Blackjack win is small, with a 5.9% chance of getting the three card flush at best and a 0.02% chance of getting suited trips at worst. In addition, the RTP of the main game (First Person Blackjack) is 99.29%, but this reduces to 96.3% if you play the 21+3 Blackjack bet.

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Aviva

About the author

Aviva is the Content Manager at PlayOJO and writes blogs, copy and all things OJOey. A copy/content marketer for over 7 years, she gets her creative juices flowing by singing, dancing (around her living room), and belly laughing regularly.

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