the 21+3 blackjack side bet—its rules, winning hands, exact probabilities, common paytables, house edge and relationship to Top 3. The blackjack game underneath can use different rules and must be evaluated separately.
On this page
- 21+3 blackjack at a glance
- How the 21+3 side bet works
- 21+3 winning hands explained
- 21+3 is not a fixed blackjack rule set
- Common 21+3 paytables
- Exact six-deck 21+3 probabilities
- How the house edge is calculated
- House edge by 21+3 paytable
- Worked expected-loss examples
- Why a small side bet can dominate your expected loss
- Does deck count change the 21+3 odds?
- 21+3 versus Top 3
- What is 21+3 Progressive?
- Is there a strategy for 21+3?
- Can 21+3 be beaten with card counting?
- Online and live-dealer 21+3
- Checklist before making a 21+3 wager
- Is the 21+3 side bet worth playing?
- Frequently asked questions
- Rules and mathematics sources
For the main game, see our blackjack rules guide and basic blackjack strategy. You can also compare other optional wagers in our guide to blackjack side bets.
21+3 is an optional blackjack side bet based on three cards: the player’s first two cards and the dealer’s face-up card. Those cards are evaluated as a three-card poker hand. Depending on the paytable, a flush, straight, three of a kind, straight flush or suited three of a kind can produce a payout.
The side bet is normally settled immediately after the initial deal. It does not matter whether the player later wins, loses, doubles, splits, busts or receives blackjack on the main wager.
21+3 blackjack at a glance
| Question | Direct answer |
|---|---|
| Which cards are used? | The player’s first two cards plus the dealer’s upcard. |
| Is it part of the main blackjack wager? | No. It is an optional and independently resolved side bet. |
| When is it settled? | Usually immediately after the first two player cards and dealer upcard are visible. |
| Which hands can win? | Common paytables recognize a flush, straight, three of a kind, straight flush and suited three of a kind. |
| What is the chance of any win in a six-deck game? | Approximately 9.676%, or about one winning result in every 10.33 side bets. |
| What is the house edge? | It depends on the deck count and paytable. Common six-deck versions range from about 3.24% to 7.14%. |
| Does basic blackjack strategy affect it? | No. The side bet is decided before hit, stand, split or double decisions are made. |
| Is Top 3 the same wager? | No. Top 3 is a separate premium-hand wager that may be offered alongside 21+3. |
How the 21+3 side bet works
The player normally places the main blackjack wager first and then chooses whether to place a separate wager in the area marked 21+3, +3 or a similar label.
Once betting closes:
- The player receives two initial cards.
- The dealer receives one face-up card.
- The player’s two cards and the dealer’s upcard form the 21+3 hand.
- The dealer compares those three cards with the posted side-bet paytable.
- The side bet is collected or paid.
- The ordinary blackjack hand continues separately.
The dealer’s hole card is not used in the standard wager. Additional cards drawn by the player or dealer are also irrelevant.
Example: winning the side bet but losing at blackjack
Suppose the player receives the 7 of hearts and 8 of hearts while the dealer shows the 9 of hearts. The three cards form a straight flush, so the 21+3 bet wins according to the posted payout.
The player’s main hand totals 15 against a dealer 9. The player can still lose the blackjack hand even though the side bet has already won.
Example: winning at blackjack but losing the side bet
Suppose the player receives an ace and king of different suits while the dealer shows a 6 of a third suit. The player has a natural blackjack, but the three cards do not form a qualifying poker hand. The main bet wins while the 21+3 bet loses.
21+3 winning hands explained
The exact categories and payouts must be read from the table placard or online game information. The following five categories are common in modern multi-deck versions.
| Hand | Definition | Example |
|---|---|---|
| Suited three of a kind | Three physically separate cards with the same rank and the same suit. This is possible only when multiple decks are used. | Three 7s of hearts from three different decks |
| Straight flush | Three consecutive ranks, all in the same suit. | 6-7-8 of clubs |
| Three of a kind | Three cards of the same rank that do not all have the same suit. | Three queens in mixed suits |
| Straight | Three consecutive ranks that are not all the same suit. | 9-10-J in mixed suits |
| Flush | Three cards of the same suit that do not form a straight flush or suited three of a kind. | 2-7-K of diamonds |
Can an ace be high or low?
Most 21+3 implementations recognize both A-2-3 and Q-K-A as straights. K-A-2 is normally not a straight. The displayed game rules remain controlling because individual software and casino versions can differ.
Why does a straight normally rank above a flush?
In three-card poker mathematics, a flush occurs more frequently than a straight. The straight is therefore treated as the higher-ranking hand in standard three-card poker ordering.
The distinction does not always affect the payout decision because many 21+3 tables list a separate fixed payout for each category. It matters when identifying which category applies and when comparing versions.
21+3 is not a fixed blackjack rule set
The side bet can be attached to many blackjack games. It does not automatically tell you:
- How many decks the main game uses
- Whether the dealer hits or stands on soft 17
- Whether blackjack pays 3:2 or 6:5
- Whether doubling after splitting is allowed
- Whether surrender is available
- Whether the game uses a shoe, continuous shuffler or RNG
- Whether split aces can be resplit
The previous version of this page described six decks, dealer standing on soft 17, unrestricted ace splitting and an eight-card automatic win as though those were universal 21+3 rules. They are not defining features of the side bet.
Evaluate the main blackjack game and the 21+3 wager independently:
- Use the main table rules to select the correct basic strategy.
- Use the 21+3 paytable and deck count to evaluate the side bet.
Common 21+3 paytables
Payouts are normally quoted as net odds “to 1.” A 10-to-1 payout on a $5 side bet returns the original $5 stake plus $50 in winnings.
| Paytable | Flush | Straight | Three of a kind | Straight flush | Suited trips |
|---|---|---|---|---|---|
| Equal-pay version | 9:1 | 9:1 | 9:1 | 9:1 | 9:1 or resolved under the posted rules |
| Enhanced Paytable A | 5:1 | 10:1 | 30:1 | 40:1 | 100:1 |
| Enhanced Paytable B | 5:1 | 10:1 | 25:1 | 40:1 | 100:1 |
These examples illustrate why the headline top prize is not enough to judge the bet. Two tables can both advertise 100-to-1 for suited trips while offering materially different returns because one pays 30-to-1 for ordinary trips and the other pays only 25-to-1.
Always copy the complete paytable rather than comparing only its largest number.
Exact six-deck 21+3 probabilities
The following probabilities assume:
- Six standard 52-card decks
- 312 physical cards before any cards are removed
- The player’s two cards and dealer upcard are drawn without replacement
- A-2-3 and Q-K-A count as straights
- K-A-2 does not count as a straight
- Suited three of a kind is classified separately
- No jokers or wild cards
There are exactly 5,013,320 unordered combinations of three physical cards from a six-deck shoe.
| Result | Number of combinations | Probability | Approximate frequency |
|---|---|---|---|
| Suited three of a kind | 1,040 | 0.020745% | 1 in 4,820.50 |
| Straight flush | 10,368 | 0.206809% | 1 in 483.54 |
| Three of a kind | 25,272 | 0.504097% | 1 in 198.37 |
| Straight | 155,520 | 3.102136% | 1 in 32.24 |
| Flush | 292,896 | 5.842356% | 1 in 17.12 |
| No qualifying hand | 4,528,224 | 90.323857% | About 9 losses in every 10 bets |
| Any listed winning hand | 485,096 | 9.676143% | 1 in 10.33 |
The most important practical number is the losing probability: before considering payout differences, a six-deck 21+3 wager loses approximately 90.32% of the time.
That does not by itself determine the house edge because the occasional winning hands pay more than even money. The full paytable must be applied to each probability.
How the house edge is calculated
For payouts quoted as net odds to 1:
Expected return = the sum of each winning probability multiplied by its total returned amount, minus the original unit wager.
In compact form:
House edge = 1 − Σ [probability × (net payout + 1)]
The “+1” includes the returned stake on a winning wager.
House edge by 21+3 paytable
| Paytable: Flush / Straight / Trips / Straight Flush / Suited Trips | Six-deck house edge | Six-deck RTP | Eight-deck house edge | Eight-deck RTP |
|---|---|---|---|---|
| 9 / 9 / 9 / 9 / 9 | 3.239% | 96.761% | 2.736% | 97.264% |
| 5 / 10 / 30 / 40 / 100 | 4.621% | 95.379% | 3.704% | 96.296% |
| 5 / 10 / 25 / 40 / 100 | 7.141% | 92.859% | 6.288% | 93.712% |
The calculations show three important points:
- The same side-bet name can have a very different house edge.
- Changing only the ordinary three-of-a-kind payout from 30-to-1 to 25-to-1 increases the six-deck house edge from approximately 4.62% to 7.14%.
- Deck count changes the probabilities, particularly for duplicate-card hands made possible by multiple decks.
Worked expected-loss examples
$5 bet at a 4.621% house edge
The average theoretical loss is:
$5 × 0.04621 = approximately $0.23 per side bet
Over 100 wagers, the total amount staked is $500 and the theoretical loss is approximately $23.10.
$10 bet at a 7.141% house edge
The average theoretical loss is:
$10 × 0.07141 = approximately $0.71 per side bet
Over 100 wagers, the total amount staked is $1,000 and the theoretical loss is approximately $71.41.
Actual short sessions will vary widely because most wagers lose and occasional winning hands produce large payouts. The house edge describes the long-run average, not what must happen in a specific session.
Why a small side bet can dominate your expected loss
Consider an illustrative game where the main blackjack wager has a 0.5% house edge under accurate basic strategy.
- $10 main wager at 0.5%: expected loss of $0.05 per hand
- $5 21+3 wager at 4.621%: expected loss of approximately $0.23 per hand
Even though the side bet is only half the size of the blackjack wager, its expected loss is more than four times as large in this example.
This is why adding “just $5” to every round can change the economics of an otherwise low-edge blackjack session.
Does deck count change the 21+3 odds?
Yes. Multiple decks make exact duplicate cards possible. Three copies of the same rank and suit cannot appear in a single deck, but they can appear in a four-, six- or eight-deck shoe.
An eight-deck shoe has a slightly higher probability of an overall winning 21+3 hand than a six-deck shoe under the assumptions used here:
- Six decks: 9.676143%
- Eight decks: 9.726397%
That does not mean every eight-deck paytable is better. A casino can offset the probability difference by lowering one or more payouts.
21+3 versus Top 3
Top 3 is a separate wager. It uses the same three cards—the player’s first two cards and dealer’s upcard—but pays only premium combinations.
Common Top 3 winning categories are:
- Three of a kind
- Straight flush
- Suited three of a kind
Top 3 typically offers much larger payouts than the standard 21+3 wager because it excludes the more frequent flush and straight outcomes.
| Feature | 21+3 | Top 3 |
|---|---|---|
| Cards used | Player’s first two cards plus dealer upcard | Player’s first two cards plus dealer upcard |
| Typical qualifying hands | Flush, straight, trips, straight flush and suited trips | Trips, straight flush and suited trips |
| Typical payout size | Moderate to large | Much larger, because wins are rarer |
| Must another wager be placed? | Usually requires the main blackjack wager | Some versions require both the blackjack and 21+3 wagers |
| Effect on blackjack strategy | None after the cards are dealt | None after the cards are dealt |
Do not combine the two paytables when calculating return. They are separate wagers with separate stakes and separate house edges.
What is 21+3 Progressive?
A progressive version adds another optional wager linked to a growing jackpot or fixed premium payouts. It commonly uses the same initial three cards but follows a separate progressive paytable.
The progressive wager does not improve the return of the ordinary 21+3 bet. Each wager must be evaluated independently:
- Main blackjack wager
- 21+3 wager
- Top 3 wager, when offered
- Progressive wager, when offered
Placing several side bets on one hand can make the total amount at risk much larger than the table’s advertised blackjack minimum.
Is there a strategy for 21+3?
There is no hit, stand, split or double decision after the three cards are revealed. For a player who is not tracking card composition, the practical decisions occur before the deal:
- Whether to place the wager
- Which paytable to accept
- How much to wager
- Whether to play it repeatedly
The strongest ordinary strategy is to choose the best available paytable and understand the expected cost before betting.
“House money” does not change the odds
Winnings already belong to the player. A $5 side bet has the same expected value whether it comes from an earlier win, a new buy-in or chips already on the table.
Being ahead in a session does not make the next 21+3 wager mathematically safer. Calling winnings “house money” can encourage larger wagers without changing the probabilities.
Chasing losses is especially dangerous
The large top payouts can make 21+3 look like a quick way to recover a losing session. Yet approximately nine out of ten six-deck wagers produce no qualifying hand.
Increasing the side bet after losses changes the amount at risk but does not improve the underlying probability.
Can 21+3 be beaten with card counting?
The answer is more nuanced than “no strategy is possible.”
Because the wager depends on the exact ranks and suits remaining in a finite shoe, previously exposed cards can change the probability of future flushes, straights and duplicate-rank combinations. In principle, a sufficiently detailed composition-dependent system can identify situations where the side bet becomes less unfavorable or potentially favorable.
The original 21+3 patent specifically discusses controls designed to reduce the impact of techniques such as card counting, shuffle tracking and card location. One example is restricting changes to the side-bet amount during a shoe.
Practical obstacles include:
- The need to track ranks and suits, not merely high and low cards
- Different paytables and deck counts
- Side-bet wagering limits
- Continuous shuffling machines
- Frequent reshuffles or shallow penetration
- Online games that independently generate or reshuffle each round
- Casino scrutiny of abrupt wager changes
A standard Hi-Lo blackjack count is not a complete 21+3 strategy. The information needed for a three-card poker side bet is different from the information used to estimate blackjack’s high-card concentration.
Online and live-dealer 21+3
RNG blackjack
An RNG game may generate each hand from a freshly shuffled virtual shoe, a finite virtual shoe or another disclosed model. Do not assume that every online game shuffles after every round. Read the game information and help file.
If every round is generated independently from a full virtual shoe, exposed cards from earlier rounds provide no useful information about the next 21+3 result.
Live-dealer blackjack
Live-dealer versions use physical cards and can offer 21+3, Top 3 or both. Check:
- Number of decks
- Paytable
- Shoe penetration
- Whether a continuous shuffler is used
- Side-bet minimum and maximum
- Whether Top 3 requires a 21+3 wager
Land-based blackjack
At a physical table, the paytable should be printed on the felt, placard or electronic display. Ask the dealer or floor supervisor to explain any category not clearly listed, particularly suited trips.
Checklist before making a 21+3 wager
- Confirm which three cards determine the result.
- Read every payout, not only the 100-to-1 headline.
- Check whether a flush qualifies.
- Check how suited trips are treated.
- Confirm whether A-2-3 and Q-K-A count as straights.
- Find the deck count.
- Determine whether the game uses a shoe, continuous shuffler or independent RNG round.
- Separate 21+3 from Top 3 and progressive wagers.
- Check the minimum and maximum side-bet amounts.
- Calculate total action from the main wager plus every side bet.
- Do not treat previous winnings as less valuable money.
- Do not chase losses with a larger side bet.
Is the 21+3 side bet worth playing?
21+3 can add a second result to the opening deal and offers much larger payouts than the main blackjack wager. That entertainment comes with a higher expected cost.
The best common paytables can have a house edge around 3%, while weaker versions can exceed 7%. By comparison, a favorable main blackjack game played with accurate basic strategy can have a house edge below 1%.
For a player focused on maximizing expected return, the main blackjack wager is normally the better place for the bankroll. A player who chooses 21+3 for entertainment should compare paytables, keep the wager small and include it when calculating total session exposure.
Frequently asked questions
What is the 21+3 side bet in blackjack?
21+3 is an optional wager using the player’s first two cards and the dealer’s upcard. The three cards are evaluated as a poker hand, independently of the result of the main blackjack wager.
What hands win the 21+3 bet?
Common modern paytables recognize a flush, straight, three of a kind, straight flush and suited three of a kind. The exact winning categories and payouts must be checked at the table.
What are the odds of winning 21+3?
Under a standard six-deck model with five winning categories, the probability of any listed winning hand is approximately 9.676%, or about one win in every 10.33 wagers.
What is the house edge on 21+3?
It depends on the deck count and paytable. In a six-deck game, an equal 9-to-1 paytable has a calculated house edge of approximately 3.239%, while a 5-10-25-40-100 paytable has an edge of approximately 7.141%.
Does 21+3 affect blackjack basic strategy?
No. The side bet is normally settled from the initial three cards before the player makes blackjack decisions. Hit, stand, split and double choices should still follow the rules of the main game.
Is Top 3 the same as 21+3?
No. Top 3 is a separate wager using the same three cards but paying only premium hands such as three of a kind, straight flush and suited three of a kind. Some tables require a 21+3 wager before Top 3 can be placed.
Can card counting beat 21+3?
Card composition can affect the wager in a finite shoe, but a practical system must track more detailed rank-and-suit information than a standard blackjack count. Wager limits, continuous shufflers, frequent reshuffles and casino countermeasures can make exploitation difficult.
Is suited three of a kind possible with one deck?
No. Suited three of a kind requires three physical copies of the same rank and suit, so it is possible only when multiple decks are combined.
Rules and mathematics sources
- Galaxy Gaming: official 21+3 product description
- Galaxy Gaming: official Top 3 product description
- Nevada Gaming Control Board: approved game rules
- U.S. patent: blackjack with a three-card poker wager
Probability note: Counting Edge calculated the six- and eight-deck figures on this page by enumerating all possible three-card physical-card combinations under the assumptions stated in the probability section. A casino’s published rules and paytable remain controlling.
