A common mistake with the 2 and 4 rule

This post is going to point out a common way that poker players incorrectly apply the ‘2 and 4’ rule.

Read on to make sure that you aren’t throwing your money away on bad draws!


What is it?

For those of you that aren’t familiar with the ‘2 and 4’ rule – it is a quick way of calculating the percentage odds of completing a draw.

It works like this:

  • Multiply your outs by 2 when you are on the flop waiting for the turn.
  • Multiply your outs by 2 when you are on the turn waiting for the river.
  • Multiply your outs by 4 when you are on the flop waiting for the turn and the river.



My hand: Ah 2h

The flop: Kh 5s 10h


I have 9 cards (or ‘outs’) that will complete my flush draw. These are as follows:

3h, 4h, 5h, 6h, 7h, 8h, 9h, Jh, Qh.


This means that an estimate of my odds of completing the flush, with either the turn card, or the river card, are:

[ 9 outs ] x [ 4 ] = [ 36% ]



A point about accuracy

The 2 and 4 rule is not precisely accurate, but it get you close enough that it doesn’t matter too much.

Check out the table below for a comparison with the actual percentage odds, for some common draws in Hold’em:

Outs Rule of 2 % Actual % Rule of 4 % Actual %
4 (gutshot) 8% 8.7% 16% 16.5%
8 (straight) 16% 17.4% 32% 31.5%
9 (flush) 18% 19.6% 36% 35%
15 (straight & flush) 30% 32.6% 60% 54.1%

Basically, the more outs there are, the more inaccurate it gets.

This shouldn’t matter though, because having more than a 50% of winning the pot means that it is profitable in the long run to call anything anyway!


The common mistake – it is rare to multiply by 4

The main point of this article is not to explain the ‘2 and 4 rule’ – most people who have played poker for a while already know it.

Instead, it is to point out a common mistake that alot of players make, which costs them significant money on the poker table by chasing draws that they should not be chasing.

The mistake is this:


“When facing a bet on the flop, do not multiply your odds by 4 unless your opponent is all-in.”


On deciding to call a bet on the flop when they are on a draw, most players will instinctively multiply their outs by 4. The reason is that they understandably think that they have both the turn and the river card to come. This is wrong.

This is wrong because you are in reality only getting to see one card from a call – the turn.  After the turn has hit, you will then be faced with another round of betting, and may be forced to pay more to try and complete your draw.

It is only when the player moves all-in on the flop that you will get to see both cards without paying more!



Let’s take the same hand above, and include some pot odds, to see how this mistake is losing players money:


My hand: Ah 2h

The flop: Kh 5s 10h


Pot size: £20

To call: £10


As we know, our flush draw has 9 outs.

Correct multiple – 2

Our call will allow us to see the turn only, and we therefore must use the rule of 2 for our percentage odds:

  • Odds of hitting the flush: [9 outs] x [2] = 18%
  • Pot odds: £30 pot*. £30 / £10 = 33%

*Always remember to include your potential call to the pot when working out pot odds!

Our odds of making the flush are LESS than the pot odds, so the correct decision here is to fold.

Incorrect multiple – 4

To really drive the point home, let’s assume that we make the common mistake, and incorrectly use the rule of 4 in the hand above:.

  • Odds of hitting the flush: [9 outs] x [4] = 36%
  • Pot odds: £30 pot*. £30 / £10 = 33%


As you can see, this simple mistake would incorrectly lead a player to think that the odds of making the flush are MORE than the pot odds, and throw his money away on a very poor draw!


When applying the rule of 2 and 4 to calculate your odds, make sure to choose the correct multiple.

Put simply, the vast majority of the time you should be using the rule of 2. It is only when your opponent goes all-in on the flop should you be using the rule of 4!


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