Single deck blackjack is the most favourable deck count for the player, worth about 0.48% compared with an 8-deck shoe, and it shifts a small number of basic strategy plays. It is only a good game at the standard 3:2 blackjack payout. At 6:5 it costs about 1.39% more, which erases the gain and then some.
Most of this page is about telling those two stories apart: the strategy changes, which are small, and the payout rule, which is large.
Why fewer decks help the player
With one deck, every card you and the dealer see changes what is left in a meaningful way. The cards in your own hand are a bigger share of what has left the deck, so they shift the odds for what comes next. A natural is also slightly more likely: about 4.8% of hands in single deck, a touch above the figure for a shoe. The effect is modest, but it changes the value of a few doubles and splits at the margins.
Against an 8-deck baseline with the same rules, the Wizard of Odds rule variation table gives:
| Decks | Effect on player return vs 8 decks |
|---|---|
| 1 | about +0.48% |
| 2 | about +0.19% |
| 4 | about +0.07% |
| 5 | about +0.03% |
| 6 | about +0.02% |
Going from 6 decks to 1 is worth roughly half a percent. That is meaningful, but it is a similar scale to the dealer-hits-soft-17 rule (0.22%) and not close to the cost of a 6:5 payout.
What changes in basic strategy
The multi-deck chart (full chart here) is still a sensible starting point at a single-deck table. A short list of borderline plays flips, because with one deck every card in your hand and on the table removes a bigger share of what is left.
We computed the optimal play for every hand with the site’s strategy engine, once for one deck and once for six, under the same rules: dealer stands on soft 17, double after split allowed, double on any two cards, no surrender, dealer peeks for blackjack, blackjack pays 3:2. These are the cells where the two charts disagree:
| Hand | Dealer upcard | Six decks | One deck |
|---|---|---|---|
| Hard 8 | 5 | Hit | Double |
| Hard 8 | 6 | Hit | Double |
| Hard 9 | 2 | Hit | Double |
| Hard 11 | A | Hit | Double |
| A,3 (soft 14) | 4 | Hit | Double |
| A,6 (soft 17) | 2 | Hit | Double |
| A,7 (soft 18) | A | Hit | Stand |
| 3,3 | 8 | Hit | Split |
| 4,4 | 4 | Hit | Split |
| 6,6 | 7 | Hit | Split |
| 7,7 | 8 | Hit | Split |
| 7,7 | 10 | Hit | Stand |
The size of the deck-count effect itself is covered in the table at the top of this page. Rule changes such as dealer hits soft 17, no double after split or a restricted doubling rule move several of these cells again, so treat the table above as the answer for this exact rule set, and use the strategy chart calculator for yours.
The differences are few and each play is close in value, so using the multi-deck chart at a single-deck table costs very little. The much bigger question is the payout, covered below.
Composition-dependent plays: the “12 against 2 or 3” type of question
Basic strategy is normally total-dependent: it looks at your total (say, 13) and the dealer’s upcard, and gives one answer. A more precise strategy is composition-dependent: it looks at the actual cards in your hand. In a shoe the difference is almost nothing. In a single deck the cards in your hand are a visible fraction of what has been removed from the deck, so the answer can occasionally flip.
The Wizard of Odds gives a single-deck example: with 13 against a dealer 2 you stand, but with the specific hand 10,3 against a 2 you hit. That sounds odd, but in a single deck the specific cards you hold are removed from the pack, and in a close decision that is enough to tip the answer. The two plays are almost equal in value, which is why it rarely matters.
How much does it matter? For a single-deck game with dealer standing on soft 17, the Wizard of Odds reports the gain from composition-dependent over total-dependent basic strategy as 0.04% for the rule set it analyses. That is tiny. Unless you are chasing every last fraction, total-dependent basic strategy is the right level for casual play.
It is a good reason not to worry about “12 against 2 and 3” when you only have a pocket of exceptions in your head. For 12 against 2 and 3, hit.
Why single deck at 6:5 is a trap
Blackjack pays 3:2 in the standard game: $15 on a $10 bet. In a 6:5 game it pays $12. The difference is $3 per natural on a $10 bet, and naturals arrive about once every 21 hands (roughly 4.8% in single deck).
Do the arithmetic for $10 bets over 100 hands:
| Item | 3:2 game | 6:5 game |
|---|---|---|
| Expected naturals in 100 hands | about 4.8 | about 4.8 |
| Payout per natural | $15 | $12 |
| Total paid on naturals | about $72 | about $58 |
| Difference | about $14 less per 100 hands |
That is $14 on $1,000 wagered, which is where the 1.39% figure comes from (the exact number is a calculation over the whole game, not just this approximation).
Now stack the effects:
| Game | Change vs 8-deck 3:2 baseline |
|---|---|
| Single deck, 3:2 | about +0.48% |
| Single deck, 6:5 | about +0.48% - 1.39% = about -0.91% |
So single deck at 6:5 is roughly 0.9 percentage points worse than an ordinary eight-deck 3:2 game, with the same other rules. Same deck, same rules, and you are roughly 0.9 points worse off than at a standard eight-deck game paying 3:2.
The trap is that it looks like the good game. It has the one-deck dealing, the hand-held cards, the feel of a “player’s game”. The sign says 6:5 in small type. Some of these tables also hit soft 17, which costs another 0.22%.
Practical advice for choosing a table
- Check the payout first. If it reads 6:5, walk away from single deck or any other deck count unless you are playing purely for entertainment.
- Then check soft 17. S17 is better for you.
- Then decks. Fewer is better, but this is the smallest of the three.
- Look at the minimum. Single-deck tables with a high minimum and a poor payout are the worst combination.
A quick rules check before you sit
Single-deck tables vary more than shoe games, so read the rule card or the felt before you play. Look for these, in this order:
- The blackjack payout (3:2 or 6:5).
- Whether the dealer hits or stands on soft 17.
- Whether you can double after a split and on any two cards. Some single-deck games restrict doubling to totals of 9, 10 and 11, which costs the player and changes which plays are available.
- Whether resplitting is allowed, and whether split aces get one card only.
If two of these four are against you, the deck count is not enough to rescue the game. Double deck is a similar story on a smaller scale: worth about 0.19% against an 8-deck baseline, and lost entirely to a 6:5 payout.
Common mistakes
- Choosing a table by deck count alone. The payout has far more influence.
- Splitting hands on a hunch. The chart is close for many single-deck plays, but close does not mean arbitrary.
- Assuming you can track what is left. Seeing the cards that have been dealt does not give you an edge on its own. Counting is a separate skill with separate rules and consequences, covered in our card counting guide.
- Over-learning rare exceptions. Learn the core chart first. The single-deck exceptions are worth a tiny fraction of a percent.
Try it yourself
Open the strategy chart tool, select one deck and your dealer rule, and compare the output with the 6-deck chart. The handful of cells that change are the ones listed above. Run the same hands in the trainer until the differences feel natural.
Single deck is the best value only when the payout is 3:2, and even then the house keeps a small edge, so play within a budget you set before you sit down.
Related guides
- Blackjack house edge explained: why the casino has an edge at all and how rules move it.
- Blackjack strategy when the dealer hits soft 17: the handful of plays that change under H17, and what the rule costs.