A9o vs 87s: preflop equity

Dealt all in against each other, A9o takes 58.85% of the pot on average and 87s takes the other 41.15%.

A9o

58.85%

Wins 58.65%, ties 0.41%

87s

41.15%

Wins 40.94%, ties 0.41%

Equity counts a tie as half a win. Exact over every board.

A9o against 87s: the numbers

Exact preflop results for A9o against 87s, in percent
HandWinsTiesLosesEquity
A9o58.6510.40640.94358.854
87s40.9430.40658.65141.146

A9o, an offsuit hand, plays 87s, a suited hand. The two hands share no rank, which makes this a pure matchup of card strength, straight chances and flush chances.

That is a modest edge, the kind that shows up over many hands and is easy to miss in one. Of every 100 boards, about 0.41 are split pots, and the equity figures already include them.

By strength against a random hand, A9o holds place 25 of 169 and 87s holds place 100.

Boards behind the percentages: 82,190,592 counted in all
HandBoards won, aboutBoards tied, aboutBoards lost, about
A9o48,206,000334,00033,651,000
87s33,651,000334,00048,206,000

Exact total: 48 deals times 1,712,304 boards. The other three counts come from the five-decimal percentages and are rounded to the nearest thousand, so read them as approximate.

A9o against 87s read as odds
HandEquity as odds (to 1)Wins one deal inLoses one deal inPot odds needed to call (to 1)
A9o1.4301.7052.4420.699
87s0.6992.4421.7051.430

The last column is the break-even price: the pot odds a call needs to offer, as a ratio of pot to call.

Who is ahead on which flops

Across the five flop textures A9o's equity moves by 17.82 points, from 45.21% on low rainbow flops (nine high or lower) to 63.03% on rainbow flops topped by a ten or better. A9o is the favorite overall but falls behind on low rainbow flops (nine high or lower).

A9o against 87s by flop texture, in percent
FlopShare of flopsA9o winsTies87s winsA9o equity
Rainbow, ten or higher25.34162.9250.20436.87163.027
Rainbow, nine or lower5.68945.0370.34854.61545.211
Two-tone46.66756.9840.21842.79857.093
Monotone5.21256.1082.34341.54957.279
Paired17.09162.1720.64937.17962.496

Read the flop types this way: rainbow has three suits, two-tone has two cards of one suit, monotone has three, and paired repeats a rank.

Compared with a random hand

Relative to a random opponent, A9o changes by -1.92 points (baseline 60.77%) and 87s by -6.79 points (baseline 47.94%).

A9o and 87s here compared with each against a random hand, in percent
CaseEquity hereAgainst a random handChange in pointsTimes the random-hand equity
A9o, all flops58.85460.773-1.9190.96842
A9o, rainbow, ten or higher63.02760.773+2.2541.03709
A9o, rainbow, nine or lower45.21160.773-15.5620.74393
A9o, two-tone57.09360.773-3.6800.93945
A9o, monotone57.27960.773-3.4940.94251
A9o, paired62.49660.773+1.7231.02835
87s, all flops41.14647.936-6.7900.85835
87s, rainbow, ten or higher36.97347.936-10.9630.77130
87s, rainbow, nine or lower54.78947.936+6.8531.14296
87s, two-tone42.90747.936-5.0290.89509
87s, monotone42.72147.936-5.2150.89121
87s, paired37.50447.936-10.4320.78238

Does a shared suit matter?

Two kinds of deal exist here. In 24 of them the hands share a suit and A9o holds 59.50%. In 24 they do not, and it holds 58.21%. A9o does better with a shared suit, by 1.29 points.

A9o against 87s by suit overlap, in percent
DealsSpecific dealsShare of dealsA9o winsTies87s winsA9o equity
Share a suit2450.0059.2740.44740.27959.497
No shared suit2450.0058.0280.36541.60758.211

How often this matchup comes up

Exactly 48 specific deals fit this matchup in one seat order, which is 0.0030% of 1,624,350; both orders together give 96, or 0.0059%.

A worked example

Try it with money: two players each put in $100 and the whole board runs out every possible way. A9o averages $117.70 from the $200, up $17.70; 87s averages $82.30, down $17.70.

In 1,000 deals of exactly this matchup, expect about 587 won outright by A9o, about 409 won outright by 87s and about 4 split.

The same matchup from the other side

If you came looking for 87s against A9o, the numbers are the same with the hands swapped: 41.15% and 58.85%.

Open the calculator with As9h against 8d7d already entered, a deal with no shared suit, and change any card to try your own hand. The matchups after it each swap one hand for a nearby one in the ranking.

How this was computed

This is an exact count with no sampling. For the 48 ways to deal one A9o and one 87s without reusing a card, grouped by suit pattern, every one of the 1,712,304 possible boards is dealt and both seven-card hands are compared. A tie counts as half a win in the equity column, and each board is counted once under each of its ten three-card flops.

Source: our own exact count from the GeorgeLiPoker poker math library. No outside data is used.

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