Two hands, one table. You are dealt a pair of 4s against a dealer 6, and a few rounds later a pair of 6s against the same 6. Both are pairs, both face one of the dealer's weakest upcards, and plenty of players split both without a second thought.
At a table that lets you double after splitting, that instinct is right for both hands. Take the rule away and it is right for only one. The 6s still split. The 4s should be hit as a plain hard 8, because the whole case for splitting them rests on a double the table no longer allows.
That makes 4s and 6s worth learning together. Both rows move with double after split (DAS), and the reasons behind each cell are simple enough to rebuild at the table instead of memorizing blind. If the broader rules of splitting are new, start with our overview of splitting pairs, then come back for these two rows.
The decision at a glance
These are the plays on the commonly published 4 to 8 deck basic strategy charts, as Wizard of Odds lays them out.
| Pair | With DAS | Without DAS | Against 7 through ace |
|---|---|---|---|
| 4,4 | Split against 5 and 6; hit against everything else | Never split; hit as hard 8 | Hit |
| 6,6 | Split against 2 through 6 | Split against 3 through 6; hit against 2 | Hit |
In two sentences: a pair of 4s splits only against a 5 or 6, and only with DAS. A pair of 6s splits against 2 through 6 with DAS, loses the dealer 2 without it, and is hit against 7 through ace under either rule.
The same rule moves the 2s and 3s rows. Without DAS, those pairs split only against 4 through 7, as our article on splitting 2s and 3s covers. The small pairs are easiest to learn as one family.
Why 4s need DAS to split
A pair of 4s is a hard 8, and hard 8 is a weak total. It cannot bust on one card, but it rarely finishes strong on one card either. Hitting it is the default, and against most upcards the default stands.
Splitting changes the shape of the hand. Each 4 becomes the start of a new hand, and the cards that help a lone 4 most are the 6 and the 7, which turn it into a 10 or an 11. Those are among the strongest doubling totals in the game, and a dealer 5 or 6, the upcards that bust most often, is exactly where you want to double them.
That is the entire case for the split, and it depends on permission to double. With DAS, a split 4 that catches a 7 becomes an 11 you can double against a 6. Without DAS, that same 11 plays for the original bet only, and the split has simply put twice the money on two hands that each start from 4. The downside arrives often, too: a 4 that draws a ten-value card becomes a 14, and four of the thirteen ranks are ten-values.
So without DAS, hit 4,4 as hard 8 against every upcard. With DAS, the split earns its place against 5 and 6 only. Our guide to double after split covers what the rule is worth across the whole chart.
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Why 6s split against weak upcards
A pair of 6s is hard 12, the lowest stiff. Standing on it wins only when the dealer busts, and hitting it risks busting with any ten-value card. Neither option is comfortable, which is why the split looks better against the right upcards.
Against a dealer 3 through 6, splitting trades one bad total for two hands that each start from 6. A 6 is not a strong start, but it beats 12: it cannot bust on its next card, and a 4 or 5 turns it into a 10 or 11. Meanwhile the dealer is showing upcards that break often, especially the 5 and 6. Putting more money out when the dealer is weakest is the same logic that runs through all the low pair splits.
The dealer 2 is the cell DAS decides. Among the low upcards, the 2 is generally the strongest for the dealer per the commonly published tables, so a split against it is marginal. Being able to double a split 6 that catches a 4 or 5 is what tips it toward splitting. Remove the double and the split no longer beats hitting the 12, which is the standard play for 12 against a 2, as our breakdown of 12 against a 2 and a 3 explains.
Against 7 through ace, the dealer is too strong for any version of the split. Two hands starting from 6 would each face a dealer who often finishes with a made hand, so splitting doubles the money in a losing spot. Hitting the 12 is the less costly choice.
Common mistakes with 4s and 6s
- Splitting 4s at a no-DAS table because they are a pair. Without the follow-up double, the split has no purpose. Hit hard 8.
- Splitting 4s against a 4 or a 7. Even with DAS, the split is limited to 5 and 6. Everywhere else, hit.
- Splitting 6s against a 7. The 7 sits right next to the weak upcards, but it starts the dealer's strong range. Hit.
- Standing on 6,6 against a 2 without DAS. The split is off, but that does not make standing correct. Hit the 12.
- Drilling one chart and playing another. Learning the DAS rows and sitting at a no-DAS table misplays exactly these cells, every time they appear.
The dealer 7 trips people up partly because 7s do split against it, as our article on splitting 7s shows. The arithmetic explains the difference: a split 7 that catches a ten-value card makes 17, while a split 6 that catches one makes 16, still a stiff.
Deck count, resplits and drilling the rows
Everything above comes from 4 to 8 deck charts. Single and double deck charts differ in a few pair cells, so if you practice for a specific game, check the chart built for that exact deck count and rule set rather than assuming the multi-deck rows carry over. Our overview of the hands that change with the rules shows how few cells move and why.
Resplitting matters as well. If a split 6 catches another 6, whether you can split again depends on the table's resplit limit, which our article on resplit limits explains.
To drill these rows, turn double after split on and run 4,4 and 6,6 against every upcard until the pattern is automatic. Then turn DAS off and repeat. 21 Trainer's strategy charts redraw automatically for the selected house rules, so you can watch the split cells vanish from the 4s row and the 6s row give up its dealer 2 as the rule flips. Pairs come up less often than hard totals in mixed practice, so give them focused sessions rather than waiting for them to appear.
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Frequently asked questions
Should you split 4s in blackjack?
Only against a dealer 5 or 6, and only when the table allows doubling after a split. Per the commonly published multi-deck basic strategy charts, a pair of 4s is otherwise played as hard 8 and hit. The split exists to turn each 4 into a 10 or 11 worth doubling, so without double after split it has no purpose.
When should you split 6s in blackjack?
With double after split allowed, split 6s against a dealer 2 through 6. Without it, split against 3 through 6 and hit against a 2. Against 7 through ace, hit under either rule. Those are the plays on the commonly published 4 to 8 deck charts, and single or double deck charts can differ, so check the chart for the exact game.
Why does double after split matter for splitting 4s?
Because the split only pays through doubling. A lone 4 that draws a 6 or 7 becomes a 10 or 11, a strong total to double against a dealer 5 or 6. Without double after split that double is not allowed, so the split just puts twice the money on two weak hands, and hitting hard 8 is the better play.
Should you split 6s against a dealer 7?
No. Basic strategy hits a pair of 6s against a dealer 7 whether or not double after split is allowed. The 7 begins the dealer's strong range, so splitting would put two bets on hands that each start from 6 against a dealer who often finishes with a made hand. Hitting the 12 is the less costly choice.
How can you practice splitting 4s and 6s?
Drill both pairs against every dealer upcard under one rule set, then switch double after split on or off and repeat until the changed cells feel natural. 21 Trainer lets you customize the rules, including double after split, redraws its strategy charts for the selected rules, and gives instant feedback with an explanation on every decision, all with virtual chips.