Updated: Dec 7, 2021
If you asked a non-poker player what they thought bluffing was, they would tell you that you take a bad hand and pretend it's a good one. They would also think that this is a huge part of the game and that you will be bluffing all of the time.
While this information isn't overtly wrong, it's not quite accurate. You are taking your worst hands and turning them into bluffs, and you should be bluffing often. However, to be a profitable player you must be doing this with hands that are most likely to succeed as bluffs. Or, out of the hand combinations you could choose, the hand is so unlikely to win at showdown that it is slightly more profitable to be turned into a bluff.
The truth is bluffing is a balancing act. You need your value hands and your bluffs to be at a perfect ratio to ensure that you can't be exploited by your opponent and to maximise profitability with your worst hands that wouldn't win the pot any other way.
Your best bluffs on the river will likely be good for a number of reasons. They have very little showdown value i.e. they will be your worst hands, they block your opponents best hands on the river, or they unblock the folding range of your opponent.
By the river your hand will either win at showdown or it won't, with no more cards to see any semi-bluffs you had on the flop or turn will have either come in or missed. The same can be said for your opponent. To make a good bluff on the river you need to seriously consider how much showdown value your hand has against your opponents range. This will change depending on the board texture and the action that's taken place throughout the hand.
If you bet the flop and the turn, your opponents range will be stronger and narrower. If you haven't bet at all then villains range will be wider and therefore weaker. When your opponents range is wider, the relative value of your weaker hands is higher, as there is a greater chance that your hand will beat theirs at showdown. When you've narrowed their range down by betting, the relative strength of your hand will be decreased.
On a draw heavy board texture (a board that contains multiple straight draws and/or flush draws), your opponents range has a higher quantity of draws compared to their range on a dry board. Depending on the river card, this could mean their range is weaker overall as it will contain several missed draws. When your opponents range is wider and weaker, this will increase the relative hand strength of your hand.
Pay attention to how the action and board texture will have changed your opponents range by the river.
Why is relative hand strength important?
Knowing your relative hand strength is essentially a way of saying what your equity (% chance to win) is likely to be in the hand. If your hand is relatively strong against your opponents range, you are more likely to win at showdown and therefore you don't need to turn your hand into a bluff!
Take and A-High flush draw for example. If your draw doesn't get there on the river, it's quite possible that your opponent was on a worse draw than your own. This is why you will rarely see good players bluffing the river with A-high, it has enough showdown value to win sometimes, and we will likely have better bluffs to choose from.
Remember that bluffing is a balancing act, and when we have the choice between picking A high vs 5 high to bluff with, 5 high is much better as it is essentially guaranteed not to win at showdown. We can't bluff with everything, so one of the criteria for a good bluffing hand is its likelihood to win at showdown.
An essential part of poker is using all of the information you have available to determine if your hand will make a great bluff on the river or not. A blocker is just a term for how a card in your hand will effect the hands that your opponents can or can't have. For example, if we have the Ace of Hearts in our hand, it would make it impossible for our opponent to have the nut flush on a 3 heart board. Given the correct situation, this Ah in our hand could be used to our advantage, if we know that our opponent can't have the nut flush, we could turn that hand into a bluff on the river.
One of the factors that makes a great bluff is blocking your opponents best value. If we are making it less likely that our opponent has a great hand to call us down with, we are increasing the chance that they fold. This idea of blocking our opponents value will help us select more profitable bluffs on rivers. The greater the chance our opponent folds, then the more likely we are to win the pot.
Other great blockers exist and you should be mindful of what to look for:
Blocking 2 pair/sets
The use of blockers is heavily dependent on the board texture and the action that has taken place. Blocking an opponents 2 pair may not be necessary if you have not bet multiple streets as your opponent is still likely to call you with a single pair. Similarly if very few draws are completed on the river, you blocking your opponents draw is now a bad thing.
One thing that makes a bad river bluff, is a combination that will increase the likelihood that your opponent will call you on the river. Unblocking your opponents folding range is critical to making a good bluff, often the combinations involved actually mean that unblocks are more important than actual blockers in many instances, as unblocking a folding range has more combinations associated with it than blocking a few value combinations.
I've written extensively about the concept of unblocking your opponents calling range, you can read more about that here:
For example, you have missed your flush draw on the river but only have 8 high, this fits the criteria that we have very little showdown value and it's a good bluffing candidate. There is a huge problem though. Us having the flush draw has made it so much less likely that our opponent has a draw. By having these flush draw blockers we reduce the chance that our opponent will fold to our bet. We can see this in the solver study here:
We can look at this example to see how our overbet bluffs are weighed up on this river. Using all the information from this article to break down the solvers decisions:
Relative Hand Strength
In this example, we have cbet the flop and overbet the turn. This means that the relative hand strength of A high isn't great, although many draws have missed on the river meaning that there is still some value in our A high combinations. Because of the quantity of missed draws, our weaker pairs that we bet the turn with, A5 and 65, do have some good showdown value. This means we don't need to bluff with these combinations.
Thinking About Our Blockers
If we think about our opponents best single pair value on the river in this situation, it is likely to be KQ. This means that blocking our opponent from having KQ is highly important. When we have a Qx hand that doesn't block our opponent from having the flush draw, we can profitably turn those hands into bluffs.
Using A6 is also okay sometimes as we have said that the relative hand strength isn't great and we block the straight that our opponent can have and are still unblocking flush draws and higher pairs with this hand.
The hands with the worst showdown value in this situation are 78 and 56. These hands do a good job unblock the folding range of our opponent provided they don't bock the flush-draw. These are the hands that we should also turn into bluffs here.
You'll also notice that we aren't turning JT into a bluff very often. This is because we don't want to be blocking the folding range as J9 and T9 are hands that our opponent will be folding when we bet. These hands should make up a large portion of villains range.
When picking the best bluffs on the river, it's important that you remain balanced and that you pick the hands that are the most likely to generate a fold from your opponent. Remember these following points when assessing hands to bluff with:
Hands with the lowest showdown value relative to the board,
Hands that block your opponents calling range (their best hands),
Hands that unblock the folding range for your opponent i.e. don't block your opponents weak value or draws.