--- title: "A9s vs A9o: preflop equity" url: "https://georgelipoker.com/equity/a9s-vs-a9o.md" canonical_url: "https://georgelipoker.com/equity/a9s-vs-a9o" last_updated: "2026-10-23" type: "reference" summary: "A9s vs A9o is close to a coin flip before the flop: 52.49% to 47.51% equity, counted exactly over every board, with the split by flop type and suit." related: ["https://georgelipoker.com/equity/a9s-vs-kjo.md", "https://georgelipoker.com/equity/a9s-vs-55.md", "https://georgelipoker.com/equity/ato-vs-a9o.md"] --- # A9s vs A9o: preflop equity A9s vs A9o is close to a coin flip before the flop: 52.49% to 47.51% equity, counted exactly over every board, with the split by flop type and suit. Dealt all in against each other, A9s takes 52.49% of the pot on average and A9o takes the other 47.51%. ## A9s against A9o: the numbers **Exact preflop results for A9s against A9o, in percent** | Hand | Wins | Ties | Loses | Equity | | --- | --- | --- | --- | --- | | A9s | 7.158 | 90.669 | 2.173 | 52.492 | | A9o | 2.173 | 90.669 | 7.158 | 47.508 | 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** | Hand | Boards won, about | Boards tied, about | Boards lost, about | | --- | --- | --- | --- | | A9s | 2,942,000 | 37,261,000 | 893,000 | | A9o | 893,000 | 37,261,000 | 2,942,000 | 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** | Hand | Equity as odds (to 1) | Wins one deal in | Loses one deal in | Pot odds needed to call (to 1) | | --- | --- | --- | --- | --- | | A9s | 1.105 | 13.970 | 46.019 | 0.905 | | A9o | 0.905 | 46.019 | 13.970 | 1.105 | 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** | Flop | Share of flops | A9s wins | Ties | A9o wins | A9s equity | | --- | --- | --- | --- | --- | --- | | Rainbow, ten or higher | 24.595 | 3.296 | 96.704 | 0.000 | 51.648 | | Rainbow, nine or lower | 6.314 | 3.322 | 96.678 | 0.000 | 51.661 | | Two-tone | 46.363 | 8.829 | 88.901 | 2.270 | 53.280 | | Monotone | 5.152 | 18.516 | 63.539 | 17.945 | 50.286 | | Paired | 17.576 | 6.201 | 92.681 | 1.118 | 52.541 | 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** | Case | Equity here | Against a random hand | Change in points | Times the random-hand equity | | --- | --- | --- | --- | --- | | A9s, all flops | 52.492 | 62.781 | -10.289 | 0.83611 | | A9s, rainbow, ten or higher | 51.648 | 62.781 | -11.133 | 0.82267 | | A9s, rainbow, nine or lower | 51.661 | 62.781 | -11.120 | 0.82288 | | A9s, two-tone | 53.280 | 62.781 | -9.501 | 0.84866 | | A9s, monotone | 50.286 | 62.781 | -12.495 | 0.80097 | | A9s, paired | 52.541 | 62.781 | -10.240 | 0.83689 | | A9o, all flops | 47.508 | 60.773 | -13.265 | 0.78173 | | A9o, rainbow, ten or higher | 48.352 | 60.773 | -12.421 | 0.79562 | | A9o, rainbow, nine or lower | 48.339 | 60.773 | -12.434 | 0.79540 | | A9o, two-tone | 46.720 | 60.773 | -14.053 | 0.76876 | | A9o, monotone | 49.714 | 60.773 | -11.059 | 0.81803 | | A9o, paired | 47.459 | 60.773 | -13.314 | 0.78092 | ## 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** | Deals | Specific deals | Share of deals | A9s wins | Ties | A9o wins | A9s equity | | --- | --- | --- | --- | --- | --- | --- | | Share a suit | 0 | 0.00 | not possible | not possible | not possible | not possible | | No shared suit | 24 | 100.00 | 7.158 | 90.669 | 2.173 | 52.492 | ## 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. ## Keep exploring 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. - [Open As9s against Ah9d in the equity calculator](https://georgelipoker.com/tools/equity-calculator.md#p1=As9s&p2=Ah9d) - [A9s combos](https://georgelipoker.com/combos/a9s.md) - [A9o combos](https://georgelipoker.com/combos/a9o.md) - [A9s vs KJo](https://georgelipoker.com/equity/a9s-vs-kjo.md) - [A9s vs 55](https://georgelipoker.com/equity/a9s-vs-55.md) - [ATo vs A9o](https://georgelipoker.com/equity/ato-vs-a9o.md) - [All hand matchups](https://georgelipoker.com/equity.md) ## 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. ## Related - [A9s vs KJo: preflop equity](https://georgelipoker.com/equity/a9s-vs-kjo.md) - [A9s vs 55: preflop equity](https://georgelipoker.com/equity/a9s-vs-55.md) - [ATo vs A9o: preflop equity](https://georgelipoker.com/equity/ato-vs-a9o.md)