The 42 Rule: Quick Pot Odds for Every Player

Calculating exact pot odds requires math that's impractical at the table. The Rule of 4 and 2 gives you accurate-enough estimates in seconds.

The Rule of 4 and 2

The "42 Rule" (or Rule of 4 and 2) is a shortcut for calculating your chances of hitting a draw:

• On the flop (two cards to come): Multiply your outs by 4
• On the turn (one card to come): Multiply your outs by 2

The result is your approximate percentage chance of completing your hand.

How It Works

"Outs" are cards that will complete your hand. If you have a flush draw (4 cards to a flush), you have 9 outs (13 cards of that suit minus the 4 you can see).

On the flop with 9 outs: 9 × 4 = 36% chance of hitting by the river.

On the turn with 9 outs: 9 × 2 = 18% chance of hitting on the river.

These estimates are close enough to the actual math (35% and 19.6%) to make good decisions.

Common Examples

• Flush draw (9 outs): 36% on flop, 18% on turn
• Open-ended straight draw (8 outs): 32% on flop, 16% on turn
• Gutshot straight draw (4 outs): 16% on flop, 8% on turn
• Two overcards (6 outs): 24% on flop, 12% on turn
• Flush draw + gutshot (12 outs): 48% on flop, 24% on turn

When to Use It

Compare your percentage to the pot odds you're getting. If the pot is $100 and you need to call $25, you're getting 4:1 odds (20%). If your draw has better than 20% equity, calling is profitable.

The 42 rule isn't perfect, but it's close enough for real-time decisions. Perfect math doesn't help if you can't calculate it before the action is on you.