An over-bet is simply a bet which is greater than the current size of the pot. Generally when people speak of over-betting they are talking about bets in excess of 1.5 times the size of the pot. Conventional wisdom over the years has stated that sticking to bet-sizes of between 2/3 and 3/4 the size of the pot works best, both with your value bets and your bluffs, however overbetting can be a powerful weapon if used correctly.

The Importance of Bet Sizing

Poker is all about getting your opponent to make mistakes. The size of your bet on a given street has a direct impact on the magnitude of the mistake your opponent makes by calling, folding or raising the bet. Let’s say you bet 1/2 the pot on the river in a hand. This gives your opponent 3/1 and therefore he only has to be ahead 25% of the time to call your bet profitably. If you bet the full size of the pot, he now has to be right 33% of the time to call profitably.

If you get to the river and want to get your opponent to fold, ideally you want to bet the exact minimum amount that will make him fold for your bet to show maximum profit. If you bet 1/2 the pot you need your bluff to work 33% of the time to show a profit, where as if you bet the full pot, you need it to work 50% of the time.

Overbetting and Expected Value

Take the earlier example of getting to the river and wishing to bluff your opponent. Perhaps you think he has quite a strong hand and it will take an over-bet to make him think twice about calling. If you bet 3x the pot in this situation you’ll need him to fold 75% of the time to make it a profitable play, but you should note that even if you do bet this much, he still only needs for his call to be correct 43% of the time to show a profit.

The table below shows how often a bluff needs to work for a given bet size in order for it to be profitable:

% of pot Required fold %
50 33%
75 43%
100 50%
150 60%
200 66%
300 75%
500 83%

Over-betting and Meta-Game

As you can see, over-bet bluffs need to work extremely often for them to be profitable and this is the reason that up until recently were not all that common. They have been popularized of late by online phenom ‘Isildur1’ who relentlessly overbets in heads-up matches, putting his opponents in all sorts of difficult spots as a result. The reason he gets away with over-betting so much is that he does it with such frequencies and balance that his opponents don’t know if any given over-bet is made as a bluff or for value. As with many plays in poker this is key to making it work correctly. If you can manipulate a suspicious opponent into calling an over-bet when you have a very strong hand because you have made him suspicious of your bet-sizing in the past then it can be very profitable.

Sample Over-betting Situation

When developing an over-betting strategy either in general, or against a specific opponent a good place to start is by over-bet bluffing when their range is capped. This means that the strongest hand they are likely to have is too weak to call an over-bet as in the example below

$1/$2 6-Max

Villain is CO ($200)
Hero is Btn ($200) with 4d5d

Fold, fold, Villain raises to $6, Hero Calls $6, fold, fold.

**Flop** ($15) Ad 9h Td

Villain bets $11
Hero calls $11

**Turn** ($37) 6s

Villain checks
Hero hero bets $25
Villain calls $25

**River** ($87) 2c

Villain checks
Hero bets $158 and is all-in
Villain folds.

In this case, when the villain check-calls the turn, he is virtually announcing that he has a weak one pair type hand that doesn’t want to fold yet and is looking for a cheap showdown. He will almost certainly bet all of his strong hands like 2 pairs, sets, and straights to protect from draws on such a wet board. When he checks the river, this is a great spot to go all-in and fold out the majority of his range, which is comprised of the above-mentioned mediocre hands with a little showdown value.

If you’re thinking about working over-betting in to your game be sure firstly to understand the math behind it, and how often you need a given over-bet size to work for it to show a profit and what pot odds you’re laying your opponent with it. Secondly, be aware it will take quite a lot of practice to become familiar with the best type of opponent and situation in which to use the over-bet profitably.