20 outs on the flop against a half-pot bet: call or fold

20 outs against a half-pot bet on the flop clear the price. You need 25.00% and you have 67.53%.

Verdict

Call

20 outs, flop, half-pot bet

  • Chance to hit by the rivertwo cards to come67.53%
  • Equity the call needs$50 into a pot of $20025.00%
  • Margin over the priceyour chance minus the price+42.53 points

How the verdict is reached

With 20 outs on the flop you hit 67.53% of the time by the river, and a half-pot bet only asks for 25.00%. That 42.53-point cushion makes this a clear call.

A total of 20 outs tends to come from stacking several ways to improve. The next card is an out 42.55% of the time, 20 in 47.

Worked through on a $100 pot

  • Pot when the bet arrives$100
  • Bet$50
  • Chips you put in$50
  • Final pot if you call$200
  • Net gain when you hit$150
  • Net loss when you miss$50
  • Probability of a hit67.53%
  • Expected value of a call+$85.06
  • Break-even equity25.00%
  • Exact margin over the price+42.5301 points
  • Outs that exactly reach the price6.23 outs
  • Margin measured in outs+13.77 outs

Expected value says the same in dollars. Win the whole pot on a hit, lose your call on a miss, add no more betting, and the call gains $85.06 on average: $101.30 in, $16.23 out, +1.701 per dollar called.

The same comparison in odds: the odds against hitting are 0.48 : 1, and the pot lays 3 : 1 on a call.

One easy error is to use 33.33%, the bet over the pot before your call, as the price. The right price is 25.00%, and the mistaken margin would be +34.1967 points. The bet over the starting pot, 50.00%, would claim +17.5301 points.

What could go wrong before the call flips

The threshold is 7 outs, a chance of 27.84%. With 20 in hand you are 13 outs clear of it.

Later betting can cut into the call. You may surrender $125.96, or 2.52 times your call, after a hit and still break even.

Price of a half-pot call if you give money back after a hit, 20 outs on the flop
Given back laterPrice with itYour chance minus priceValue of the callCall?
$025.00%+42.53 points+$85.06Call
$1026.32%+41.21 points+$78.31Call
$2528.57%+38.96 points+$68.18Call
$5033.33%+34.20 points+$51.30Call
$10050.00%+17.53 points+$17.53Call

Which chance to use

Whether you count one card or two, the answer is a call. The river figure is 67.53%, the next-card figure is 42.55%, and both are measured against 25.00%.

20 outs against a half-pot bet, one view per row
Cards countedChanceMargin over priceValue of the callVerdict
By the river, two cards67.53%+42.5301 points+$85.06Call
Next card only42.55%+17.5532 points+$35.11Call

Neighbors of this draw

One out can change the answer, so the table lists the counts just below 20. Each out moves the chance roughly 2.50 points against the 25.00% price.

Outs 16 to 20 on the flop against a half-pot bet
OutsBy the riverMarginVerdict
16 outs56.98%+31.98 pointsCall
17 outs59.76%+34.76 pointsCall
18 outs62.44%+37.44 pointsCall
19 outs65.03%+40.03 pointsCall
20 outs, this page67.53%+42.53 pointsCall

Where the bet size flips the call

Look down the margin column to see where the draw stops paying. Every row uses 20 outs on the flop and a bet of a different size.

Nothing in the list is too big to call: 20 outs reach 67.53% on the flop, above every price on the page.

20 outs on the flop against every bet size
Bet sizeEquity neededMarginVerdict
quarter-pot16.67%+50.86 pointsCall
third-pot20.00%+47.53 pointsCall
two-fifths-pot22.22%+45.31 pointsCall
half-pot, this page25.00%+42.53 pointsCall
two-thirds-pot28.57%+38.96 pointsCall
three-quarter-pot30.00%+37.53 pointsCall
pot-size33.33%+34.20 pointsCall
1.25x-pot35.71%+31.82 pointsCall
1.5x-pot37.50%+30.03 pointsCall
2x-pot40.00%+27.53 pointsCall
3x-pot42.86%+24.67 pointsCall
4x-pot44.44%+23.09 pointsCall

How this is computed

The hit chance comes straight from combinations. Out of 1,081 pairs of unseen cards, 351 miss every out, so you hit 67.53% of the time.

Read the verdict with its limits in mind. The call is the full bet, so the break-even equity is $50 / $200 = 25.00%. A hit takes the whole pot, no later betting happens, and the 47 unseen cards are all equally likely, with none removed for an opponent's cards.

Computed from the closed form by the GeorgeLiPoker math library.

Updated

Questions

How should you respond to a half-pot bet on the flop when you hold 20 outs?

By the numbers it is a call. 20 outs on the flop hit 67.53% by the river, a half-pot bet needs 25.00%, and the margin is +42.53 points. That assumes you call the full $50 and no more betting follows, and it values the call at +$85.06 per $100 pot.

What is the minimum number of outs for a half-pot bet on the flop?

Against 25.00%, the first count that works on the flop is 7, at 27.84%. At 6 the chance is 24.14%, too low. Compared with that threshold, your 20 outs are 13 above.

Does it matter whether you count one card or two against a half-pot bet?

Pick the number that matches the street plan: 67.53% for seeing both cards for one bet, 42.55% for paying card by card. Both face 25.00%, and the verdict is call either way.

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