There are some hands in blackjack that who’s basic strategy plays just cause our brains to revolt. Our brains get hung up on the numbers, are so focused on the numbers, that they miss the finer points. One such hand is a soft 18.
A soft 18 consists of a 7 and an Ace. Our brains see that 18 and want to stand. But they are missing the fact that this is one of those flexible hands that have a chance of building into a better hand simply by hitting it. You do not have to worry about busting because you can reduce that Ace from 11 to 1 if you need to
In fact you cannot bust if you hit a soft 18. An Ace, 2 or 3 will give you a hand total of 19, 20 or 21—all strong hands. Anything 4 or more will cause you to reduce the Ace and you have decent ground to build strong.
This is why basic strategy dictates the following plays based on dealer up cards:
Dealer 2: stand
Dealer 3-6: double down
Dealer 7 and 8: stand
Dealer 9, 10, Ace: hit
As you can see, you are receiving another card more often than not. The only times you stand are the times when the dealer is in a good chance to build a hand stronger than yours if you were to hit.
But the soft 18 confusion does not end here. There must be something about having an Ace in hand that makes it a harder hand to know how to play.
I have heard of players who are fine and well with a two card soft 18, but if they start with a two card 7, hit and receive an Ace, the confusion begins again. But the truth is that a two card soft 18 is no different than a three card soft 18. It is still a soft 18 and that Ace can still be reduced, and a 4/3 is still worth 7. So the same plays can be made.
Your blackjack strategy for a soft 18 does not differ from your blackjack strategy for a soft 18 made up of three cards. Or even from four cards. The whole point is that you have an Ace and some other cards that are worth 7. Every player needs to train themselves to see past the obvious hand total on the surface and look at what cards are making up that hand total.