A9s vs A9o: preflop equity

Dealt all in against each other, A9s takes 52.49% of the pot on average and A9o takes the other 47.51%.

A9s

52.49%

Wins 7.16%, ties 90.67%

A9o

47.51%

Wins 2.17%, ties 90.67%

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

A9s against A9o: the numbers

Exact preflop results for A9s against A9o, in percent
HandWinsTiesLosesEquity
A9s7.15890.6692.17352.492
A9o2.17390.6697.15847.508

One side is a suited hand, the other is an offsuit hand. The cards are the same ranks, so any difference in equity comes from suitedness alone.

A9s leads by less than 5 points of equity, so the result of any one deal is close to a toss-up. Of every 100 boards, about 90.67 are split pots, and the equity figures already include them.

The hand ranking puts A9s at 18 and A9o at 25 out of 169 starting hands.

Boards behind the percentages: 41,095,296 counted in all
HandBoards won, aboutBoards tied, aboutBoards lost, about
A9s2,942,00037,261,000893,000
A9o893,00037,261,0002,942,000

24 specific deals times 1,712,304 boards gives the exact total. The won, tied and lost counts are approximations from the five-decimal percentages, rounded to the nearest thousand.

A9s against A9o read as odds
HandEquity as odds (to 1)Wins one deal inLoses one deal inPot odds needed to call (to 1)
A9s1.10513.97046.0190.905
A9o0.90546.01913.9701.105

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

Split by what the flop looks like, A9s peaks at 53.28% on two-tone flops and bottoms out at 50.29% on monotone flops. A9s stays ahead on all five textures, and the gap between its best and worst is only 2.99 points, so the shape of the flop hardly changes who is favored.

A9s against A9o by flop texture, in percent
FlopShare of flopsA9s winsTiesA9o winsA9s equity
Rainbow, ten or higher24.5953.29696.7040.00051.648
Rainbow, nine or lower6.3143.32296.6780.00051.661
Two-tone46.3638.82988.9012.27053.280
Monotone5.15218.51663.53917.94550.286
Paired17.5766.20192.6811.11852.541

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

Each hand has a baseline against a random hand: 62.78% for A9s, 60.77% for A9o. Here the change is -10.29 and -13.26 points.

A9s and A9o here compared with each against a random hand, in percent
CaseEquity hereAgainst a random handChange in pointsTimes the random-hand equity
A9s, all flops52.49262.781-10.2890.83611
A9s, rainbow, ten or higher51.64862.781-11.1330.82267
A9s, rainbow, nine or lower51.66162.781-11.1200.82288
A9s, two-tone53.28062.781-9.5010.84866
A9s, monotone50.28662.781-12.4950.80097
A9s, paired52.54162.781-10.2400.83689
A9o, all flops47.50860.773-13.2650.78173
A9o, rainbow, ten or higher48.35260.773-12.4210.79562
A9o, rainbow, nine or lower48.33960.773-12.4340.79540
A9o, two-tone46.72060.773-14.0530.76876
A9o, monotone49.71460.773-11.0590.81803
A9o, paired47.45960.773-13.3140.78092

Does a shared suit matter?

These two classes cannot share a suit in any legal deal, so there is only one row to read: A9s holds 52.49% in every deal of this matchup.

A9s against A9o by suit overlap, in percent
DealsSpecific dealsShare of dealsA9s winsTiesA9o winsA9s equity
Share a suit00.00not possiblenot possiblenot possiblenot possible
No shared suit24100.007.15890.6692.17352.492

How often this matchup comes up

Out of 1,624,350 ways to deal two seats two cards each, 24 are A9s in one seat and A9o in the other (0.0015%); with the seats swapped too, 48 (0.0030%).

A worked example

Worked example: both players commit $100, so $200 sits in the middle. Over every board, A9s' average share is $104.98 (a gain of $4.98) and A9o's is $95.02 (a loss of $4.98).

Per 1,000 deals: A9s wins about 71, A9o wins about 22, and about 907 end in a split pot.

The same matchup from the other side

The reversed view, A9o against A9s, shows 47.51% for A9o and 52.49% for A9s. It is the same count, so it redirects here.

The calculator link fills in As9s against Ah9d, a deal where the two hands share no suit. Change any card to test your own hand. The neighboring matchups below swap one of the two hands for one of similar strength.

How this was computed

This is an exact count with no sampling. For the 24 ways to deal one A9s and one A9o 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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