One of the more complex but important concepts to understand in poker is probability. It is critical to be able to calculate your odds of improving your hand during the betting rounds. This allows you to make more informed decisions when deciding whether to call or fold. In addition, understanding poker probability can help you spot and avoid bad beats.
Probability is calculated by counting the number of ways a hand can be improved and then dividing this by the total number of possible 5-card hands (the sample space; 52 cards
A simple and reliable shortcut for calculating the odds of improving a hand is to use the rule of four and two, which is based on counting the number of outs you have and multiplying this by 4. For instance, if you’re holding 7-8 unsuited as your hole cards and the flop comes 9-10-A, this gives you eight outs (8 x 4) and gives you a 32% chance at making your straight.
This calculation does not take into account other players’ cards, which may be in your opponent’s hand, or any card that could be dealt to yourself during the next round. However, it is a good starting point for more advanced calculations.