--- title: "ATo vs A9o: preflop equity" url: "https://georgelipoker.com/equity/ato-vs-a9o.md" canonical_url: "https://georgelipoker.com/equity/ato-vs-a9o" last_updated: "2026-10-23" type: "reference" summary: "ATo is a big favorite over A9o before the flop: 72.03% to 27.97% equity, counted exactly over every board, with the split by flop type and suit." related: ["https://georgelipoker.com/equity/ato-vs-kjo.md", "https://georgelipoker.com/equity/ato-vs-55.md", "https://georgelipoker.com/equity/kjs-vs-a9o.md"] --- # ATo vs A9o: preflop equity ATo is a big favorite over A9o before the flop: 72.03% to 27.97% equity, counted exactly over every board, with the split by flop type and suit. Over all 1,712,304 boards that can follow this deal, ATo finishes with 72.03% of the pot and A9o with 27.97%. ## ATo against A9o: the numbers **Exact preflop results for ATo against A9o, in percent** | Hand | Wins | Ties | Loses | Equity | | --- | --- | --- | --- | --- | | ATo | 66.704 | 10.649 | 22.647 | 72.029 | | A9o | 22.647 | 10.649 | 66.704 | 27.971 | ATo meets A9o, and both are offsuit hands. Sharing a rank is the signature of a dominated hand, since the weaker hand is usually out-kicked when the shared rank shows up. That is a clear edge, 72.03% to 27.97%, but A9o still wins often enough that one hand proves nothing. Ties are 10.65% of the outcomes here; each tied board gives both hands half the pot. ATo ranks number 19 of 169 starting hands, and A9o ranks number 25, by equity against a random hand. **Boards behind the percentages: 184,928,832 counted in all** | Hand | Boards won, about | Boards tied, about | Boards lost, about | | --- | --- | --- | --- | | ATo | 123,355,000 | 19,693,000 | 41,881,000 | | A9o | 41,881,000 | 19,693,000 | 123,355,000 | Exact total: 108 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. **ATo 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) | | --- | --- | --- | --- | --- | | ATo | 2.575 | 1.499 | 4.416 | 0.388 | | A9o | 0.388 | 4.416 | 1.499 | 2.575 | 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 The flop changes the picture. ATo does best on rainbow flops topped by a ten or better, at 76.91%, and worst on low rainbow flops (nine high or lower), at 62.30%. ATo stays ahead on all five textures. **ATo against A9o by flop texture, in percent** | Flop | Share of flops | ATo wins | Ties | A9o wins | ATo equity | | --- | --- | --- | --- | --- | --- | | Rainbow, ten or higher | 24.003 | 72.550 | 8.711 | 18.739 | 76.906 | | Rainbow, nine or lower | 7.042 | 60.123 | 4.359 | 35.518 | 62.302 | | Two-tone | 46.477 | 69.088 | 7.603 | 23.309 | 72.890 | | Monotone | 5.144 | 63.740 | 7.773 | 28.487 | 67.627 | | Paired | 17.334 | 55.770 | 24.909 | 19.321 | 68.225 | Rainbow flops have three suits, two-tone flops repeat one suit, monotone flops are all one suit, and paired flops repeat a rank. ## Compared with a random hand Compared with a random opponent, this matchup shifts ATo from 62.72% by +9.31 points and A9o from 60.77% by -32.80 points. **ATo 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 | | --- | --- | --- | --- | --- | | ATo, all flops | 72.029 | 62.722 | +9.307 | 1.14838 | | ATo, rainbow, ten or higher | 76.906 | 62.722 | +14.184 | 1.22614 | | ATo, rainbow, nine or lower | 62.302 | 62.722 | -0.420 | 0.99330 | | ATo, two-tone | 72.890 | 62.722 | +10.168 | 1.16211 | | ATo, monotone | 67.627 | 62.722 | +4.905 | 1.07820 | | ATo, paired | 68.225 | 62.722 | +5.503 | 1.08774 | | A9o, all flops | 27.971 | 60.773 | -32.802 | 0.46025 | | A9o, rainbow, ten or higher | 23.094 | 60.773 | -37.679 | 0.38000 | | A9o, rainbow, nine or lower | 37.698 | 60.773 | -23.075 | 0.62031 | | A9o, two-tone | 27.110 | 60.773 | -33.663 | 0.44609 | | A9o, monotone | 32.373 | 60.773 | -28.400 | 0.53269 | | A9o, paired | 31.775 | 60.773 | -28.998 | 0.52285 | ## Does a shared suit matter? When the hands share a suit, ATo holds 72.13%; when they do not, it holds 71.67%. ATo does better with a shared suit, by 0.46 points. **ATo against A9o by suit overlap, in percent** | Deals | Specific deals | Share of deals | ATo wins | Ties | A9o wins | ATo equity | | --- | --- | --- | --- | --- | --- | --- | | Share a suit | 84 | 77.78 | 66.788 | 10.688 | 22.524 | 72.132 | | No shared suit | 24 | 22.22 | 66.412 | 10.513 | 23.075 | 71.668 | ## How often this matchup comes up Out of 1,624,350 ways to deal two seats two cards each, 108 are ATo in one seat and A9o in the other (0.0066%); with the seats swapped too, 216 (0.0133%). ## A worked example Put $100 each into a $200 pot and deal every board once: ATo averages $144.06 back, ahead of its $100 by $44.06, while A9o averages $55.94, short of its $100 by $44.06. In 1,000 deals of exactly this matchup, expect about 667 won outright by ATo, about 226 won outright by A9o and about 107 split. ## The same matchup from the other side The reversed view, A9o against ATo, shows 27.97% for A9o and 72.03% for ATo. It is the same count, so it redirects here. ## Keep exploring Open the calculator with AsTh against Ad9c 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. - [Open AsTh against Ad9c in the equity calculator](https://georgelipoker.com/tools/equity-calculator.md#p1=AsTh&p2=Ad9c) - [ATo combos](https://georgelipoker.com/combos/ato.md) - [A9o combos](https://georgelipoker.com/combos/a9o.md) - [ATo vs KJo](https://georgelipoker.com/equity/ato-vs-kjo.md) - [ATo vs 55](https://georgelipoker.com/equity/ato-vs-55.md) - [KJs vs A9o](https://georgelipoker.com/equity/kjs-vs-a9o.md) - [All hand matchups](https://georgelipoker.com/equity.md) ## How this was computed Method: exact enumeration. The 108 specific deals are grouped by suit pattern, each is run against all 1,712,304 boards, and both seven-card hands are scored. Equity adds half of every tie, and flop textures are tallied over the ten flops inside each board. Source: our own exact count from the GeorgeLiPoker poker math library. No outside data is used. ## Related - [ATo vs KJo: preflop equity](https://georgelipoker.com/equity/ato-vs-kjo.md) - [ATo vs 55: preflop equity](https://georgelipoker.com/equity/ato-vs-55.md) - [KJs vs A9o: preflop equity](https://georgelipoker.com/equity/kjs-vs-a9o.md)