"The majority of players are looking for reasons to fold. I am looking for reasons to play." ~ Daniel Negreanu The Rule of 2 and 4 The
Rule of 2 and 4 are quick shortcuts to help us work out the percentage needed to get a draw in Texas No-Limit Hold'em. These shortcuts aren’t exact. However, they are good enough for doing quick probabilities in our head at the tables. |

**The Rule of 2**The Rule of 2 states: Multiply your number of outs by 2 to get the approximate percentage of a draw you have on the turn or the river.

For example, let's say you have a flush draw after the flop.

- There are 2 cards of the same suit in your hand and 2 cards of the same suit on the board.

That makes 4 cards to a flush. - There are 13 cards to a suit, and 9 cards (outs) that can help you make a flush (13 - 4 = 9).
- Use the Rule 2 to approximate your percentage of hitting a flush on the next card.

2 x 9 = 18% probability of getting your flush.

- There are 13 cards to a suit, and 9 cards (outs) that can help you make a flush (13 - 4 = 9).
- There are 52 cards in the deck minus 2 cards in your hand and 3 cards on the board.
- This leaves 47 cards remaining (52 - 5 = 47).
- (9/47) = 19% probability of getting your flush.

*The Rule of 2 works because there are 52 cards in the deck*

and 52 goes into one hundred approximately twice.and 52 goes into one hundred approximately twice.

**The Rule of 4**The Rule of 4 is used when you are considering an all-in move after the flop and will see both the turn and river cards. Multiply your number of outs by 4 to get the approximate percentage of a draw.

Like the Rule of 2 example, you have a flush draw after the flop.

- There are 2 cards of the same suit in your hand and 2 cards of the same suit on the board.

That makes 4 cards to a flush.

There are 13 cards to a suit, you have 9 cards (outs) remaining that can help you make your flush (13 - 4 = 9). - Use the Rule 4 to approximate your percentage of hitting a flush on the next two cards.

4 x 9 = 36% probability of making your flush.

- There are 52 cards in the deck minus 2 cards in your hand and 3 cards on the board.

Consequently, there are 47 cards remaining (52 – 2 – 3 = 47). - There are 9 cards that will help you make your flush.

Thus, there are 47 - 9 = 38 cards that will not make your flush on the turn. - The probability of not making your flush on the turn is 38/47.
- Subtract one from the numerator and denominator for the river card which is 37/46.
- Multiply both numbers together and subtract from 1 to determine your probability of making a flush.
- 1- 38/47 x 37/46 = 35% probability of making your flush.

Once again, that’s close and useful for quick estimate at the tables.

Note: The Core Math Chapter of Mastering Poker Math provides more detail on how this equation is derived.

Charles W. Clayton

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Copyright© 2020 - 2021

All Rights Reserved