In poker, you can never know exactly what cards your opponent is holding; all you can do is try to figure out his possible holdings by evaluating his actions as the hand progress. We call all of his perceived possible holdings his ‘range’.
For example, if a straightforward player raises pre-flop in early position he gives you information about his range, specifically that it is comprised of mostly very strong starting hands. Whether or not he continuation bets on the flop gives you further information about what he could be holding. As the hand progresses it is your job as a poker player to evaluate this range as best you can based on all of his actions in the hand, in order to make decision which nets you the most money against what you perceive to be his range.
Why Do We Need to Construct a Range?
Learning how to construct a range for your opponent is the most important skill you need to develop if you want to advance as a poker player. This is how all of the best players make it to the top, and how they manage to make seemingly insane calls on the river and have them be correct so often.
The good news is that evaluating ranges isn’t something that’s terribly difficult to learn. It’s nothing more than applying basic logic and with practice it’s easy to become quite good at.
Your job starts when your opponent makes his first action in the hand, and continues right until the river if the hand progresses that far, by which time you should have a very good idea of his holding, and consequently, evaluating the right play should be relatively straightforward.
Example Range Calculation
The best way to demonstrate hand reading and constructing a hand range for your opponent is with an example:
The game is $1/$2 6-max no limit holdem. The villain is a decent regular player who plays reasonably loosely before the flop.
HERO (MP): $215
Preflop: Hero is MP with Ad As
Fold, Hero raises to $6, CO calls $6, 3 folds.
Flop: ($15) Ks 8c 3c (2 players)
Hero bets $12, CO calls $12
Turn: ($39) Ks 8c 3c 2h (2 players)
Hero bets $34, CO calls $34
River: ($107) Ks 8c 3c 2h Kd
What should we do?
Preflop the villains range can be very wide as he is in position and will call with all pairs, a lot of broadway hands like KJs, suited connectors and suited 1 gappers like 78s and 46s, and sometimes premium hands for deception.
On the flop, his calling range is KK, 88, 33, Kx, 8x, A3s, all combinations of flush draws and 99-QQ.
After the turn, this range is narrowed significantly. It is not a good bluffing card for us, so the villain will tend not to get stubborn with medium strength hands and should believe us, leaving his range weighted towards Kx and flush draws almost entirely.
So if we think that villain can have KT, KJ, KQ, AK and lets include a stubborn QQ, as well as the following additional flush draws: AQ, AJ, AT, A5, A4, A3, A2, QJ, QT, JT, T9, 67, 56, 45, what should we do?
Since he has a lot of missed draws in his range that he might bluff with, and QQ which he might even value bet with we should check, as betting lets him fold everything we beat and call or raise with everything that beats us, or even bluff raise and make us fold the best hand.
So if we check should it be to check-fold or check-call? We have about 50% equity vs. this range, so we should definitely call if we think he’ll bet his whole range. However, he might check back all of his ace high flush draws as these have showdown value. Even so, we still have 40% equity and should call anything but an overbet.
This is a simple example of dynamically evaluating a villain’s range as the hand progresses. Based on his actions we can deduce that when he bets the river, he has a range which we have 40-50% equity against, but will rarely call with a worse hand, so we should check-call.
The more you do this, the easier it will become and in time you’ll be able to do it during live play, enabling you to make the best decision every time.