When it comes to blackjack basic strategy, knowing when to split is important but is not necessarily as easy to remember or understand as when to hit or stand. When deciding whether to split a pair, you take into consideration not only your own cards and the hands you are likely to be dealt, but in many cases you also have to consider what hand the dealer likely has and how that would affect your decision. Luckily, however, with some pairs the decision is easy.
If you have a pair of eights, you will always split that pair. It doesn’t matter what card the dealer is showing. The reason for that is that a hard 16 is a bad hand. It is a stiff hand (12-16), which is the worst kind of hand in blackjack. Stiff hands are bad because you have a high probability of losing no matter what you do. If you stand, your hand total isn’t very high so you have a good chance of being outdrawn by the dealer. In fact, since the dealer will always hit until a 17, you will always be outdrawn with a stiff hand unless the dealer busts.
However, if you hit a stiff hand you have a good chance of busting. For example, if you have a hard 16, there are only five cards that can improve your hand (ace, 2, 3, 4, 5). Conversely, there are eight cards that can cause you to bust (6, 7, 8, 9, 10, J, Q, K). For that reason, any time you can avoid having a stiff hand you do so.
By splitting a pair of eights you trade in a stiff hand of a hard 16 for two hands starting with an eight. Blackjack basic strategy takes into account that you are more likely to draw a card with a value of 10 than any other value, since 4/13 of the cards have a value of 10. By splitting a stiff hand and giving yourself the potential for two hands of 18, you have greatly increased your chances of winning. However, even if you don’t get a hand as good as 18, if you end up with anything other than a stiff hand (or busting), then splitting that pair was beneficial.