The problems start when your hand value is 12 or more. If you are at 12 then a hit of a 10 value card will result in a bust. At a rudimentary calculation you face a 32% chance of busting. However if you stand then you have a hand value of only 12. The chance of losing out to the dealer is significantly higher if you stand. Let us now take the other extreme. If your hand value is 20 then again by a rudimentary calculation you face and 92% chance of busting if you hit. For the intermediate hand values the chance of busting lies between 32% and 92%. So the question is at what hand value you should stop hitting.
Unfortunately, the answer is not straightforward. It depends to a large extent on the dealer’s face up card and whether you are holding a hard hand or soft hand. It also depends on the exact rules of the blackjack variant that you are playing to a smaller extent. The answer has been obtained after computer simulation of tens of thousands of deals. The optimum blackjack strategy for standing is briefly explained for an eight decks American Blackjack variant in which the dealer stands on soft 17 and checks for blackjack upfront.
If you hold a hard hand then the rules are as follows. For a value of 12 you stand only when the dealer has 4, 5 or 6. For values of 13 to 16 you stand when the dealer has 6 or less. You have to hit for higher dealer values because the dealer has a good chance of reaching near about 20. For values of 17 and above you always stand.
You can be more aggressive with a soft hand because if you exceed 21 you can convert an ace from 11 to 1. In this case you always hit up to a hand value of 17. You always stand for a hand value of 19 or more. With a hand value of 18 you stand if the dealer has 8 or less.
