Small pairs: when to split twos, threes, fours and sixes

Aces and eights are split against everything, and tens are never split. The pairs in between are the ones that need a chart: twos, threes, fours and sixes. They add up to 4, 6, 8 and 12, all poor totals, yet the right play is not always to hit. It is to split when the dealer is weak, and the exact edge of that range depends on a rule most tables print in small type.

The rules assumed throughout are the ones the Blackjack Coach chart teaches: six decks, dealer stands on soft 17, double after split (DAS) allowed and late surrender. The Play listing states those rules; the no-DAS version further down is a comparison for other tables and is not something the app teaches.

The chart

With DAS allowed, the four pairs play like this:

• 2-2 and 3-3: split against a dealer 2 to 7, otherwise hit.
• 4-4: split against a 5 or 6, otherwise hit.
• 6-6: split against a dealer 2 to 6, otherwise hit.

Without DAS the ranges shrink:

• 2-2 and 3-3: split against 4 to 7 only; hit against 2 and 3.
• 4-4: never split; always hit.
• 6-6: split against 3 to 6 only; hit against a 2.

Why splitting twos, threes and sixes works

Unsplit, a 4 or a 6 is a hand you have to build with at least two more cards. Split, each hand begins on a single 2 or 3, which cannot bust on the next card, and you get two chances at a strong total with two stakes against a dealer who is likely to fail.

That last part is the dealer's side. In a six-deck game a dealer showing a 2 busts 35.4% of the time, and one showing a 7 busts 26.2% (see the dealer bust rates for every up-card). Against an 8 or higher the dealer's hands are strong enough that a hand starting on a 2 or 3 is behind, and basic strategy goes back to hitting.

Sixes are different. Together they make 12, and a hard 12 is a hand you hit against most up-cards, since only a ten-value card busts it: 4 ranks in 13, or 30.8%. Against a dealer 7 or better a 12 simply hits, and splitting would put two weak 6s against a strong card. Against a dealer 2 to 6 the dealer is the likelier one to go over, so you split to put a second bet on that, and each hand starts on a 6 that cannot bust. Unsplit, a 12 against a 2 or 3 is a hit (see hard 12 against a 2 or 3), yet a pair of 6s against the same cards does better as two hands.

Fours are the odd one out

A pair of 4s totals 8. As one hand it is just a hit, and nobody doubles it. Split it, and each hand starts on a 4. Add a 5, 6 or 7 and you hold 9, 10 or 11, the totals that can be doubled for a good return. Three ranks of 13 do that, or 23.1% per hand.

That doubling is the whole case for splitting fours, and it only exists if you are allowed to double after splitting. It also only pays when the dealer is weak enough to risk the larger stake, which is why the range is just 5 and 6, the two up-cards with the highest bust rates (41.8% and 42.3%). Without DAS, the extra value vanishes and you are left with two weak 4s. Basic strategy then hits the 8 against every dealer card.

What taking away DAS does to the others

When a split hand cannot be doubled, its good draws are worth less. The calls that leaned most on doubling are the ones that tip to a hit: 2-2 and 3-3 against a dealer 2 or 3, and 6-6 against a 2. That is why the grid has dashed cells at the edge of each range and solid cells in the middle.

Where this sits in the pairs chart

None of these ranges extends past a 7. Against an 8, 9, ten or ace, every one of these pairs is hit. The fixed cases are covered in why you always split aces and eights, never split tens and splitting nines against a 7.

The common mistakes run both ways: hitting 6-6 against a 5 because 12 looks like a hitting hand, and splitting 4-4 against a 10 because two hands feels better than one. In Blackjack Coach you can choose a play, read the explanation and review your mistakes, so a few small-pair hands against a 2, a 6 and an 8 are a quick way to fix the ranges.