Soft 18: Ace-Seven, and Why It Is Not a Good Hand
Updated
18 looks like a hand you keep. Against a nine, a ten or an ace it is not — you hit it, and standing costs you real money. Ace-seven is the most misplayed hand in blackjack, because it is three different decisions wearing the same number.
- Against 2: stand (double on H17 tables).
- Against 3, 4, 5, 6: double if allowed, otherwise stand.
- Against 7 and 8: stand.
- Against 9, 10, ace: hit. Standing against a 9 costs 8.3%.
One total, three answers
The trouble with soft 18 is that 18 is a respectable number and an ace is a free second chance, and those two facts pull in opposite directions. Against a weak card the ace lets you double without risk of busting. Against a strong card the 18 is simply not enough and the ace lets you try again for nothing.
The middle band — 7 and 8 — is the only place where standing pat is right, because 18 beats or ties the dealer’s most likely finish.
What each option is actually worth
Six decks, dealer stands on soft 17, ace-seven specifically. Bet of 1 unit. Against a 6 and against a 9 — the two ends of the hand:
The nine is where the money is lost
Standing on soft 18 against a nine loses 18.3% of your bet. Hitting loses 9.9%. The difference, 8.3%, is larger than the entire house edge of the game several times over — on a single decision.
The reason is that a dealer nine finishes on 19 more often than anything else. Your 18 loses to 19. Hitting cannot bust you, because the ace drops to 1 if you go over, so the only thing you risk is turning an 18 into a 17 or worse — and against a nine that is a risk worth taking.
The one cell the soft-17 rule moves
Against a 2, an S17 table wants you to stand (+0.124) and an H17 table wants you to double. It is the only cell on the soft 18 row that the rule touches, and the margin is small either way.
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By Martin Kosek · every number on this site is computed by us, not copied.
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