Small blackjack strategy effects

14 July 2019

By John Grochowski

Not all basic strategy plays are created equal. Some blackjack hands are such close calls it takes only a slight difference in composition or in the proportion of remaining cards to flip the best play.

A few months ago I mentioned hard 16 vs. a dealer’s 10 as one of those plays. Basic strategy charts tell you to hit, but if your 16 consists of three or more cards and includes a 4 or a 5, the odds favor standing.

A reader who called himself Des wrote to ask if the hand was that close, couldn’t the cards exposed on the table make a strategy difference?

“In six-deck games where everybody’s cards are face up, there’s a lot of information out there,” Des wrote. “You don’t have to be a card counter to see what’s on the table for one hand. If what’s in your own hand can make a strategy flip all by itself, shouldn’t other players’ cards make a difference, too?”

Cards on board can make a strategy difference, something that was explored by Fred Renzey in his “Blackjack Bluebook II,” first released in 2003 and with an expanded edition on 2017.

The effect is small. You’re not going to get an edge on the game with these small changes. But if you can take even tiny nicks out of the house edge with little effort, why not go for it? For those who want to go all out to turn the tables, Renzey details a counting system, too.

But to stick with the small nicks, Renzey adjusts play for a “Magnificent 7” hands according to the balance on the table between 10-value cards and four denominations of “babies” – 2s, 3s, 4s and 5s.

In a six-deck game, you should stand on your 16 vs. 10 whenever there are more babies than 10s on the table. If you look around other players’ hands and see five 10-values and six or more small cards, then basic strategy flips and the better play is to stand.

Other basic strategy flips come on hard 12 vs. 4 when there are as many or more 10s as babies (hit instead of stand); hard 13 vs. 2 when there are at least five more 10s than babies (hit instead of stand); hard 9 vs. 2 when there are at least five more babies than 10s (double instead of hit); Ace/7 vs. 2 when there are at least five more babies than 10s (double instead of stand); Ace/8 vs. 6 when there are at least five more babies than 10s (double instead of stand); and 11 vs. Ace when there are at least six more babies than 10s (double instead of hit).

Note that most of those flips come when there is an excess of at least five cards on one side. Other than 16 vs. 10, the only razor-thin close call is 12 vs. 4. The rest require extraordinary swings given that you’re relying on a single deal around the table.

How much of a dent can all this make in the house edge? Renzey calculates your game as 0.03% in a two- or six-deck game, or 0.05% in a single-deck game, should you find one with rules good enough to entice you to play.

Those are small gains even by blackjack standards, where you gain 0.22% when the dealer stands on all 17s instead of hitting soft 17, or lose 0.1% if you’re not permitted to resplit pairs.

The gain is tiny, but it’s there for the taking.

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