Double and split rule variations

Key facts

Removing double after split raises the house edge by about 0.14 percentage points; restricting doubles to 9–11 costs about 0.09 and to 10–11 about 0.18, per Wizard of Odds.
Forbidding resplits costs the player about 0.10 points; allowing resplit of aces is worth about 0.08 and drawing to split aces about 0.19.
Without double after split, multi-deck basic strategy stops splitting 2s and 3s against a 2 or 3, 4s against a 5 or 6, and 6s against a 2.
When doubling is limited to hard 9–11, every soft double in the chart becomes a hit or a stand.
Forbidding doubling entirely costs about 1.48 points; forbidding both doubling and splitting about 1.91 points.

Doubling and splitting are the only two decisions that let you put more money on the table after you have seen the dealer’s upcard, so every rule that limits them has a measurable cost. The largest common restriction, doubling on 10 and 11 only, costs about 0.18 percentage points; the most common, no double after split, about 0.14. Each also moves specific cells of basic strategy, which is why the rule placard and your chart need to agree.

Doubling restrictions

Wizard of Odds measures each rule against its eight-deck, S17, double-any-two, DAS baseline. Signs are flipped here so that positive means the house edge rises.

Doubling rule	Effect on house edge	Where common
Double on any first two cards	baseline	North America, Australia
Double on 9, 10, 11 only	+0.09	Continental Europe, UK
Double on 10, 11 only	+0.18	Some single and double-deck games, Reno-style rules
Double on any number of cards	−0.23	Spanish 21, Super Fun 21, Pontoon
No doubling	+1.48	Rare
Triple down on any two cards	−1.64	Promotional

The 9–11 restriction removes the soft doubles. Under the six-deck S17 chart, those are soft 13 and 14 against 5–6, soft 15 and 16 against 4–6, and soft 17 and 18 against 3–6. Each becomes a hit, except soft 18, which becomes a stand. The 10–11 restriction additionally removes hard 9 against 3–6, which becomes a hit. Nothing else in the chart changes, because hard 10 and 11 remain available. The doubling guide explains each of these cells; the site’s own profile allows doubling on any two cards.

Some casinos allow doubling on three or more cards, usually in variants. That rule is worth 0.23 points because it rescues hands such as 5-3-3 (hard 11) that would otherwise be hit at single stakes.

Double after split

DAS lets you double on a hand produced by a split, for example doubling the 6-5 you make after splitting 6s against a 5. Wizard of Odds measures its removal at +0.14 points; BlackjackInfo quotes +0.12 for six decks. Most of its value comes from low pairs, which are worth splitting mainly because the resulting hands so often become doubling hands against a weak dealer card.

The four-to-eight-deck S17 chart changes in three places when DAS is removed:

Pair	With DAS	Without DAS
2s and 3s	Split vs 2–7	Split vs 4–7; hit vs 2 and 3
4s	Split vs 5–6	Never split; hit
6s	Split vs 2–6	Split vs 3–6; hit vs 2

Aces, 8s, 7s and 9s are unaffected: always split aces and 8s, split 7s against 2–7, split 9s against 2–6 and 8–9, never split 5s or 10s. The splitting guide covers the reasoning hand by hand.

A table that permits doubling but not after splitting will usually say “No double after split” on the placard, or nothing at all. Ask. The question is specific: “If I split, can I double on the new hands?”

Resplitting and the number of hands

Most shoe games allow a pair to be split to four hands, meaning three splits in total. Wizard of Odds’ figures:

Resplit rule	Effect on house edge
Split to four hands	baseline
Split to three hands only	+0.01
No resplitting (two hands)	+0.10
No splitting at all	+0.57
No doubling and no splitting	+1.91

The jump from +0.01 to +0.10 is because a second split is rare and a third very rare; forbidding resplits altogether, by contrast, hits every pair drawn to a pair. Strategy barely changes. Wizard of Odds’ guidance is to treat a hand you cannot resplit as a hard total, so a second pair of 8s after splitting 8s plays as hard 16. The one exception is aces, below.

Split aces: one card, resplit, or draw

Split aces are a special case everywhere. The standard rule gives each split ace exactly one card and forbids further action; an ace and ten made this way counts as 21, not a natural, and pays even money. Variations:

Split-ace rule	Effect on house edge
One card to each ace, no resplit	baseline (most shoe games)
Resplit aces allowed	−0.08
Draw to split aces allowed	−0.19
Double, double for less, or stand after splitting aces	−0.15
Ace-ten after splitting aces pays 3:2	−0.21
No splitting of aces	+0.18

Resplit aces matters because the next card to a split ace is another ace roughly one time in thirteen, and a one-card 12 (ace-ace counted 2 or 12) is a poor hand to be stuck with. Drawing to split aces is worth more than twice as much but is rarely offered in standard blackjack; Spanish 21 and Super Fun 21 include it. The strategy adjustment Wizard of Odds gives for the standard multi-deck game is small: if aces cannot be resplit and you are dealt a second pair of aces, double against a 6 only if drawing to split aces is allowed, and otherwise hit.

When splitting aces is forbidden entirely, a pair of aces plays as soft 12: hit against everything. That rule is uncommon in casinos but appears in some online and video versions.

Worked example: the cost of a split without DAS

Take a $10 bet on a pair of 2s against a dealer 3 in a six-deck S17 game. With DAS, you split, and each resulting hand has a chance of landing on 9, 10 or 11 and doubling against a weak upcard; the full package is worth slightly more than hitting the hard 4. Without DAS, the split still costs a second $10, but the follow-up hands can only be hit or stood, and the expected value falls below that of simply hitting the 4. The chart therefore flips from split to hit against the 3.

The sums are small on any one hand, which is why the whole DAS rule is worth 0.14 points rather than a full percent. But they recur every time a low pair meets a low upcard, and a player who splits 2s, 3s and 4s “as usual” at a no-DAS table is paying for a rule they do not have.

Combining the restrictions

A continental game with double on 9–11 only (+0.09), no DAS (+0.14) and one split only (+0.10) is about 0.33 points worse than the site’s six-deck S17 DAS profile, before the no-hole-card settlement rule discussed in European no-hole-card rules. A Reno-style double-deck game with double on 10–11 only (+0.18) and H17 (+0.22) gives back about 0.40 points, which is more than the double-deck benefit of 0.19. The method for adding these up is in how rule variations change the house edge.

The priority at the table is the same as elsewhere: payout, then soft 17, then these rules. But among the doubling and splitting rules, DAS and the doubling restriction are the two to confirm before you sit, because they are both worth a tenth of a point or more and both change what you should do with cards in your hand.

Frequently asked

What does DAS mean in blackjack?

Double after split: after splitting a pair you may double down on either resulting hand. It is worth about 0.14 percentage points to the player and changes which low pairs are worth splitting.

Is double on 10 and 11 only a big deal?

It costs about 0.18 points, roughly the same as H17. You lose the doubles on hard 9 and on every soft hand. Double on 9–11 only costs about half that, 0.09 points.

Should I still split aces if I only get one card each?

Yes. One card to each split ace is the standard rule and basic strategy already assumes it. Being allowed to draw further (rare) is worth about 0.19 points extra; being forbidden to split aces at all costs about 0.18.

How many times can you split?

Usually to a maximum of four hands (three splits). Limiting to three hands costs about 0.01 points; one split only (two hands) costs about 0.10. Aces are often excluded from resplitting.

Sources & editorial notes

By Blackjack World Tour · Updated 2026-10-12 · Owner review pending. Sources were checked on the update date.

Where this guide states a strategy decision without naming rules, it assumes the site profile: six decks, dealer stands on soft 17, double after split, no surrender. Basic strategy cannot guarantee a winning hand.

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Ten hands under the stated profile, with the reasoning after every answer.

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