3 outs on the flop: chance to hit

On the flop, two cards are still to come. With 3 outs, the chance that an out lands by the river is 12.49%, and the sections below price that chance against a bet.

Chance to hit by the river

12.49%

3 outs, two cards to come

  • Chance on the next card6.38%
  • Odds against by the river7.01 : 1
  • Rule of 4 estimate-0.49 points from the exact chance12%

The count behind 3 outs on the flop

This count leaves you empty-handed 87.51% of the time. A 12.49% chance can still be worth chasing, but only when the bet you face is a small fraction of the pot.

  • Unseen cards47
  • Your outs3
  • Cards that miss44
  • Pairs of cards with no out946
  • Pairs with at least one out135
  • Chance by the river12.49%
  • Chance on the next card6.38%
  • Odds against hitting7.01 : 1
  • Estimate from the rule of 412%
  • Error of the rule of 4-0.49 points

Chance by the river = 1 - C(u - k, 2) / C(u, 2), with u = 47 unseen cardsFor 3 outs: 1 - C(44, 2) / C(47, 2) = 1 - 946 / 1,081 = 12.49%Next card = 3 / 47 = 6.38%

Think in pairs. The 47 unseen cards form 1,081 pairs, and only 946 avoid every out. Subtract and you land on 135 helpful pairs, a 12.49% chance.

The quick estimate of 12% and the exact 12.49% nearly agree, separated by 0.49 points.

No adjustment is needed on the flop with 3 outs. The plain rule of 4 gives 4 x 3 = 12%.

Which holding has 3 outs?

One overcard to top pair fits this count exactly, with 3 outs. Memorizing counts like this lets you read the chance straight from the table on this page.

A shared out has a price: 4.07 points for the first, and 12.49 points in all with 3 shared. Subtract any shared outs before you compare with a bet.

3 outs on the flop when some outs are shared with a better hand
Shared outsEffective outsChance by the riverChance given up
0312.49%0.00 points
128.42%4.07 points
214.26%8.23 points
300.00%12.49 points

The bets 3 outs can call on the flop

The table prices every bet against 12.49%. Margin is your chance minus the equity a call needs, and no bet size is a call.

Past 16.65% of the pot, the price beats your 12.49%. On a $100 pot that line is $16.65.

3 outs on the flop against every bet size, with your chance by the river at 12.49%
Bet sizeEquity a call needsMargin over itVerdict
1/4 pot16.67%-4.18 pointsFold
1/3 pot20.00%-7.51 pointsFold
2/5 pot22.22%-9.73 pointsFold
1/2 pot25.00%-12.51 pointsFold
2/3 pot28.57%-16.08 pointsFold
3/4 pot30.00%-17.51 pointsFold
full pot33.33%-20.84 pointsFold
1.25x pot35.71%-23.23 pointsFold
1.5x pot37.50%-25.01 pointsFold
2x pot40.00%-27.51 pointsFold
3x pot42.86%-30.37 pointsFold
4x pot44.44%-31.96 pointsFold

Nearby counts on both streets

Neighboring counts help you judge a close draw. One out more or less shifts the chance by roughly 3.98 points on this street.

Counts near 3: the chance by the river on the flop and on the turn
OutsFlop, by the riverTurn, by the river
14.26%2.17%
28.42%4.35%
3 (this page)12.49%6.52%
416.47%8.70%
520.35%10.87%

When a bet buys only one card

When more betting is still to come, the fair test is the next card alone. 6.38% against the 25.00% that a half-pot call needs is -18.62 points, which reads Fold.

Whether you count one card or two, 3 outs clear none of the 12 bet sizes.

How this is computed

The chance to hit by the river from the flop is 1 - C(u - k, 2) / C(u, 2), where u = 47 unseen cards and k is your effective outs. For 3 outs that is 1 - 946 / 1,081 = 12.49%. The chance on the next card is k / 47, here 6.38%.

The rule of 4 figure is 4 x k, here 12%, and its error is that figure minus the exact chance in percentage points, here -0.49 points.

Two assumptions sit behind the page. First, all 47 unseen cards are equally likely, with no cards taken out for an opponent. Second, each bet is called in full on a $100 pot, so you pay one bet to play for a pot that holds the pot and both bets.

Computed from the closed form by the GeorgeLiPoker math library.

Updated

Questions

What are the odds of hitting with 3 outs on the flop?

With 3 outs on the flop you hit by the river 12.49% of the time, about 12 of every 100 hands, and on the next card 6.38%. The odds against hitting by the river are 7.01 : 1, since 946 of 1,081 pairs of unseen cards hold no out.

What does the rule of 4 say for a count of 3?

The rule of 4 gives 12% for 3 outs against an exact 12.49%, an error of -0.49 points. That is close enough to use at the table.

How many bet sizes can 3 outs on the flop pay for?

At 12.49% by the river, you can call none of the 12 bet sizes. A half-pot bet needs 25.00%, a margin of -12.51 points, so against half the pot the verdict is Fold. The largest bet you can call is 16.65% of the pot, or $16.65 on a $100 pot.

Should I count every out when a rival could be drawing too, with 3 outs?

Take them off the count first. With one shared out the chance by the river falls from 12.49% to 8.42%, and with 3 shared it falls to 0.00%, a loss of 12.49 points. The effective count is then 0 outs.

Check your own hands against the numbers

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