--- title: "1 Out on the Flop: Odds to Hit" url: "https://georgelipoker.com/outs/1-outs-flop.md" canonical_url: "https://georgelipoker.com/outs/1-outs-flop" last_updated: "2026-10-22" type: "reference" summary: "How often does 1 out hit on the flop? 4.26% by the river. Odds against, shortcut error and the bet sizes you can call." related: ["https://georgelipoker.com/outs.md"] --- # 1 Out on the Flop: Odds to Hit How often does 1 out hit on the flop? 4.26% by the river. Odds against, shortcut error and the bet sizes you can call. Holding 1 out once the flop is dealt gives you a 4.26% chance by the river. Below you will find what that means as odds, how far the quick rule drifts and which bet sizes you can call. - Chance to hit by the river: 4.26% (1 out, two cards to come) - Chance on the next card: 2.13% - Odds against by the river: 22.5 : 1 - Rule of 4 estimate: 4% (-0.26 points from the exact chance) ## The count behind 1 out on the flop 4.26% is a modest chance. Over many hands the draw lands about 4 times in 100, and that is rarely enough for a large bet. - Unseen cards: 47 - Your outs: 1 - Cards that miss: 46 - Pairs of cards with no out: 1,035 - Pairs with at least one out: 46 - Chance by the river: 4.26% - Chance on the next card: 2.13% - Odds against hitting: 22.5 : 1 - Estimate from the rule of 4: 4% - Error of the rule of 4: -0.26 points - Chance by the river = 1 - C(u - k, 2) / C(u, 2), with u = 47 unseen cards - For 1 out: 1 - C(46, 2) / C(47, 2) = 1 - 1,035 / 1,081 = 4.26% - Next card = 1 / 47 = 2.13% Here is the arithmetic for 1 out. Both cards must miss for the draw to fail: that is 1,035 pairs out of 1,081. The remaining 46 pairs give you 4.26%. The rule of 4 gives 4% against an exact 4.26%, a gap of -0.26 points. That is close enough to use at the table. No adjustment is needed on the flop with 1 out. The plain rule of 4 gives 4 x 1 = 4%. ## Which holding has 1 out? A count of 1 means a single card helps. It comes from your own count of helpful cards, not from a standard draw. Not every out is clean. Here is the chance once shared outs are removed: from 4.26% down to 0.00% when it is shared. 1 out on the flop when some outs are shared with a better hand | Shared outs | Effective outs | Chance by the river | Chance given up | | --- | --- | --- | --- | | 0 | 1 | 4.26% | 0.00 points | | 1 | 0 | 0.00% | 4.26 points | ## The bets 1 out can call on the flop Here is the price list. For each bet size it shows the equity a call needs, your margin over it and the verdict, and no verdict is Call. 1 out on the flop against every bet size, with your chance by the river at 4.26% | Bet size | Equity a call needs | Margin over it | Verdict | | --- | --- | --- | --- | | 1/4 pot | 16.67% | -12.41 points | Fold | | [1/3 pot](https://georgelipoker.com/call-or-fold/1-outs-flop-vs-third-pot.md) | 20.00% | -15.74 points | Fold | | 2/5 pot | 22.22% | -17.97 points | Fold | | [1/2 pot](https://georgelipoker.com/call-or-fold/1-outs-flop-vs-half-pot.md) | 25.00% | -20.74 points | Fold | | [2/3 pot](https://georgelipoker.com/call-or-fold/1-outs-flop-vs-two-thirds-pot.md) | 28.57% | -24.32 points | Fold | | [3/4 pot](https://georgelipoker.com/call-or-fold/1-outs-flop-vs-three-quarter-pot.md) | 30.00% | -25.74 points | Fold | | [full pot](https://georgelipoker.com/call-or-fold/1-outs-flop-vs-pot-size.md) | 33.33% | -29.08 points | Fold | | 1.25x pot | 35.71% | -31.46 points | Fold | | 1.5x pot | 37.50% | -33.24 points | Fold | | 2x pot | 40.00% | -35.74 points | Fold | | 3x pot | 42.86% | -38.60 points | Fold | | 4x pot | 44.44% | -40.19 points | Fold | The line between call and fold is a bet of 4.65% of the pot, or $4.65 on a $100 pot. Stay at or under it and the draw pays for itself. ## Nearby counts on both streets Compare 1 out with the counts on either side. Each step is worth near 4.16 points on the flop, and the other street is shown next to it. Counts near 1: the chance by the river on the flop and on the turn | Outs | Flop, by the river | Turn, by the river | | --- | --- | --- | | 1 (this page) | 4.26% | 2.17% | | [2](https://georgelipoker.com/outs/2-outs-flop.md) | 8.42% | 4.35% | | [3](https://georgelipoker.com/outs/3-outs-flop.md) | 12.49% | 6.52% | - [1 out on the turn](https://georgelipoker.com/outs/1-outs-turn.md): 2.17% on the river. - [2 outs on the flop](https://georgelipoker.com/outs/2-outs-flop.md): 8.42% by the river. ## When a bet buys only one card Think about what the bet buys. If you must call again on the turn, only 2.13% counts for the flop call. A half-pot price of 25.00% leaves -22.87 points, which is a fold. The verdicts hold up on one card: no bet size is a call, matching the two-card count. ## Questions ### How good is a draw with 1 out on the flop? With 1 out on the flop you hit by the river 4.26% of the time, about 4 of every 100 hands, and on the next card 2.13%. The odds against hitting by the river are 22.5 : 1, since 1,035 of 1,081 pairs of unseen cards hold no out. ### Is the rule of 4 close enough for 1 out? The rule of 4 gives 4% for 1 out against an exact 4.26%, an error of -0.26 points. That is close enough to use at the table. ### When should I call or fold with 1 out on the flop? At 4.26% by the river, you can call none of the 12 bet sizes. A half-pot bet needs 25.00%, a margin of -20.74 points, so against half the pot the verdict is Fold. The largest bet you can call is 4.65% of the pot, or $4.65 on a $100 pot. ### How many points do I lose if outs are shared with a better hand? Take it off the count first. With your one out shared, the chance by the river falls from 4.26% to 0.00%, a loss of 4.26 points, and the effective count is then 0 outs. ## 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 1 out that is 1 - 1,035 / 1,081 = 4.26%. The chance on the next card is k / 47, here 2.13%. The rule of 4 figure is 4 x k, here 4%, and its error is that figure minus the exact chance in percentage points, here -0.26 points. Read the figures as a card count. All 47 unseen cards stay in, including any your opponent holds, so the figures describe your outs, not a matchup. Bets are called in full against a $100 pot with no extra money assumed. Computed from the closed form by the GeorgeLiPoker math library. ## Related pages - [Outs calculator](https://georgelipoker.com/tools/outs-calculator.md): Enter your own count and street. - [Pot odds calculator](https://georgelipoker.com/tools/pot-odds-calculator.md): Enter a pot and a bet to see the equity a call needs. - [Outs and odds to hit](https://georgelipoker.com/outs.md): The chance to hit for every count on both streets. - [1 out on the turn](https://georgelipoker.com/outs/1-outs-turn.md): The same count with one card to come. - [Pot odds for a third-pot bet](https://georgelipoker.com/pot-odds/third-pot.md): The equity a third-pot call needs. - [Pot odds for a pot-size bet](https://georgelipoker.com/pot-odds/pot-size.md): The equity a pot-size call needs. - [Hand equity](https://georgelipoker.com/equity.md): Your chance to win against a named hand. ## Related - [Outs and Odds to Hit by Street](https://georgelipoker.com/outs.md)