Apr

19

2016

Splitting 5’s In Blackjack And Why It’s a No-No

One of the absolutes in blackjack is that you should never split 5s. Most players aren’t even tempted, because they recognize they have a much stronger building block for a hand when they start with 10 than starting each of two hands with 5s.

Nontheless, I received an email recently from a player who challenged the notion. He reasoned that when the dealer had a weak card such as a 5 or 6 face up, he had an edge. If he was dealt another 5, he wanted the opportunity to get a third bet on the table.

When the dealer has a low card face up, there’s a better way to press home our advantage. Double down on any dealer face-up cards except 10 or Ace, and you have a better investment than splitting the pair.

Let’s compare expected outcomes for our six-deck game if you have 5-5 and the dealer has 6 face up.

If you double down, your expected profit per \$1 of your original wager is 58.8 cents.

If you just hit, that expected profit is 29.4 cents.

If you split, the expected profit is 10.4 cents .

The weakness of starting a hand with 5 shows in decreased profit when you split the pair even when the dealer has a weak card face up. We make nearly six times as much money without any more risk when we double down instead of splitting. Just hitting isn’t the optimal play, but it brings nearly three times the return of splitting with less money risk.

The emailer who started this discussion told me the play has been profitable for several years, and that when dealing himself hands and home, splitting looked like his best option.

I’m not going to convince him, and that happens. Sometimes players have results outside the ordinary for extended periods, and if we don’t keep records, sometimes the results aren’t quite what our memories tell us. Nonetheless, the odds of the game tell us the best play for a pair of 5s is to double down against 2 through 9, and stand against 10 or Ace. It is not a close call.