Single Deck Blackjack Strategy
Single deck blackjack holds a special place in the game’s history. It was the standard format before casinos introduced multiple decks partly as a countermeasure against card counters in the 1960s and 1970s. Today, genuine single deck games with favorable rules are rare, but they do exist in some land-based casinos and a small number of online platforms. When you find one with good rules, it offers the lowest possible house edge of any blackjack format. For background on how single deck blackjack developed, Wikipedia’s blackjack article covers the history.
This page covers the strategy adjustments needed for single deck play and helps you evaluate whether a single deck game you find is actually worth playing. Before reading this, make sure you have the standard multi-deck Basic Strategy Chart down solidly – single deck adjustments are modifications on top of that foundation.
Why Single Deck Strategy Differs
With only 52 cards in play, the removal of each card has a larger proportional effect on the remaining deck composition than in a multi-deck game. When you are dealt a 10, you have removed 1 out of 16 ten-value cards in the deck – about 6.25% of all tens. In a 6-deck shoe, removing one ten represents only 1 out of 96 tens – just over 1%. This compositional sensitivity changes the optimal strategy for several hands.
Additionally, in single deck games, the dealer typically deals cards face-down to players (hand-held games), which means both your cards and other players’ cards are eventually visible – giving you more information about the deck composition on any given hand.
The Single Deck Rule Warning
Before getting into strategy, a critical warning: many single deck games at modern casinos have been deliberately structured with unfavorable rules to offset the lower house edge that single deck naturally provides. The most common trap is the 6:5 blackjack payout.
A single deck game paying 6:5 on blackjack is worse for the player than a standard 6-deck game with 3:2. The deck count advantage is completely wiped out and then some by the payout change. Always check the blackjack payout before assuming a single deck game is good.
| Rule Set | Single Deck House Edge |
|---|---|
| 3:2 payout, S17, DAS, late surrender | ~0.15% |
| 3:2 payout, H17, no DAS, no surrender | ~0.35% |
| 6:5 payout, S17 | ~1.45% |
| 6:5 payout, H17, no DAS | ~1.8% |
Key Strategy Differences: Single Deck vs. Multi-Deck
The following are the most important adjustments when moving from a standard 6-deck game to single deck with favorable rules (S17, DAS, 3:2):
Hard Hand Adjustments
| Hand | Dealer | Multi-Deck | Single Deck (S17) |
|---|---|---|---|
| Hard 8 | 5 | Hit | Double |
| Hard 8 | 6 | Hit | Double |
| Hard 9 | 2 | Hit | Double |
| Hard 11 | Ace | Hit | Double |
| Hard 12 | 2 | Hit | Stand |
| Hard 12 | 3 | Hit | Stand |
Soft Hand Adjustments
| Hand | Dealer | Multi-Deck | Single Deck (S17) |
|---|---|---|---|
| Soft 13 (A+2) | 4 | Hit | Double |
| Soft 14 (A+3) | 4 | Hit | Double |
| Soft 18 (A+7) | 2 | Double (Ds) | Stand |
| Soft 19 (A+8) | 4 | Stand | Double |
| Soft 19 (A+8) | 5 | Double (Ds) | Double |
| Soft 19 (A+8) | 6 | Double (Ds) | Double |
Pair Adjustments
| Pair | Dealer | Multi-Deck | Single Deck (S17, DAS) |
|---|---|---|---|
| 2-2 | 2 | Split (DAS) / Hit | Split |
| 2-2 | 3 | Split (DAS) / Hit | Split |
| 3-3 | 2 | Split (DAS) / Hit | Split |
| 3-3 | 3 | Split (DAS) / Hit | Split |
| 6-6 | 2 | Split (DAS) / Hit | Split |
| 4-4 | 4 | Hit (no DAS) | Split |
| A-A | All | Split | Split |
Single Deck and Card Counting
Single deck blackjack was the original target of card counting systems. With only 52 cards, the count becomes meaningful very quickly – after just a few hands, the true count can shift dramatically. For card counters, genuine single deck games with deep penetration (70%+ of the deck dealt before reshuffling) offer the richest conditions of any blackjack format.
In practice, casinos that offer single deck games with good rules and deep penetration are aware of this and take countermeasures – frequent reshuffling, bet limits, and careful surveillance. Single deck tables often reshuffle after only 50 – 60% of the deck, which reduces the counting advantage significantly.
Finding Good Single Deck Games Online
Genuine single deck blackjack with favorable rules is more common online than in many physical casinos. When evaluating an online single deck game, check:
Blackjack payout
Must be 3:2. Decline any single deck game paying 6:5.
Dealer rules
S17 preferred over H17.
Doubling rules
Can you double on any two cards, or only 9-10-11?
Surrender
Late surrender available?
Reshuffle frequency
In RNG single deck games online, the deck is typically reshuffled after every hand, making card counting irrelevant but keeping the game rules-accurate for basic strategy purposes.