A8s vs A9o: preflop equity

Dealt all in against each other, A9o takes 65.25% of the pot on average and A8s takes the other 34.75%.

A8s

34.75%

Wins 27.30%, ties 14.91%

A9o

65.25%

Wins 57.79%, ties 14.91%

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

A8s against A9o: the numbers

Exact preflop results for A8s against A9o, in percent
HandWinsTiesLosesEquity
A8s27.29714.90857.79534.751
A9o57.79514.90827.29765.249

The matchup pits a suited hand against an offsuit hand. Because the hands share one rank, the one with the higher kicker is ahead when that rank pairs and the other hand is mostly drawing.

A9o is the clear favorite, though A8s gets there on roughly one board in 3. About 14.91% of boards chop the pot, which is why equity sits slightly above the win figure for both hands.

By strength against a random hand, A8s holds place 21 of 169 and A9o holds place 25.

Boards behind the percentages: 61,642,944 counted in all
HandBoards won, aboutBoards tied, aboutBoards lost, about
A8s16,827,0009,190,00035,627,000
A9o35,627,0009,190,00016,827,000

Exact total: 36 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.

A8s against A9o read as odds
HandEquity as odds (to 1)Wins one deal inLoses one deal inPot odds needed to call (to 1)
A8s0.5333.6631.7301.878
A9o1.8781.7303.6630.533

The last column is the smallest pot odds, written as a pot-to-call ratio, at which a call breaks even with this equity.

Who is ahead on which flops

Across the five flop textures A9o's equity moves by 8.34 points, from 60.76% on paired flops to 69.10% on rainbow flops topped by a ten or better. A9o stays ahead on all five textures.

A8s against A9o by flop texture, in percent
FlopShare of flopsA8s winsTiesA9o winsA8s equity
Rainbow, ten or higher24.58823.81514.17762.00830.903
Rainbow, nine or lower6.36031.2783.59465.12833.075
Two-tone46.52729.31411.24759.43934.937
Monotone5.19233.09110.56656.34338.374
Paired17.33323.62931.22345.14839.240

A rainbow flop shows three suits, a two-tone flop repeats one suit, a monotone flop is a single suit, and a paired flop repeats a rank.

Compared with a random hand

Against one random hand instead, A8s holds 61.94% and A9o holds 60.77%. Facing each other changes that by -27.19 points for A8s and +4.48 points for A9o.

A8s and A9o here compared with each against a random hand, in percent
CaseEquity hereAgainst a random handChange in pointsTimes the random-hand equity
A8s, all flops34.75161.944-27.1930.56101
A8s, rainbow, ten or higher30.90361.944-31.0410.49889
A8s, rainbow, nine or lower33.07561.944-28.8690.53395
A8s, two-tone34.93761.944-27.0070.56401
A8s, monotone38.37461.944-23.5700.61950
A8s, paired39.24061.944-22.7040.63348
A9o, all flops65.24960.773+4.4761.07365
A9o, rainbow, ten or higher69.09760.773+8.3241.13697
A9o, rainbow, nine or lower66.92560.773+6.1521.10123
A9o, two-tone65.06360.773+4.2901.07059
A9o, monotone61.62660.773+0.8531.01404
A9o, paired60.76060.773-0.0130.99979

Does a shared suit matter?

Does suit overlap move the numbers? A9o has 66.01% when the hands share a suit and 64.87% when they do not. A9o does better with a shared suit, by 1.14 points.

A8s against A9o by suit overlap, in percent
DealsSpecific dealsShare of dealsA8s winsTiesA9o winsA8s equity
Share a suit1233.3326.46115.06358.47633.992
No shared suit2466.6727.71614.83057.45435.131

How often this matchup comes up

Counting specific cards, A8s against A9o appears in 36 of the 1,624,350 ordered heads-up deals (0.0022%), and in 72 when the seats are swapped too (0.0044%).

A worked example

Try it with money: two players each put in $100 and the whole board runs out every possible way. A9o averages $130.50 from the $200, up $30.50; A8s averages $69.50, down $30.50.

Per 1,000 deals: A9o wins about 578, A8s wins about 273, and about 149 end in a split pot.

The same matchup from the other side

A9o against A8s adds nothing new: it is 65.25% for A9o and 34.75% for A8s, the same figures reversed.

Open the calculator with As8s against Ah9d 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

The figures are counted, not estimated: 1,712,304 boards for every suit pattern of the 36 specific deals, with both seven-card hands compared each time. Equity gives half a win for a tie. For the flop rows, a board is counted once under each of the ten flops inside it.

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

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