A9s vs ATo: preflop equity

If ATo and A9s get all the chips in before the flop, ATo owns 67.86% of the pot in the long run and A9s owns 32.14%.

A9s

32.14%

Wins 27.08%, ties 10.11%

ATo

67.86%

Wins 62.81%, ties 10.11%

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

A9s against ATo: the numbers

Exact preflop results for A9s against ATo, in percent
HandWinsTiesLosesEquity
A9s27.07910.11362.80832.135
ATo62.80810.11327.07967.865

The matchup pits a suited hand against an offsuit hand. Sharing a rank is the signature of a dominated hand, since the weaker hand is usually out-kicked when the shared rank shows up.

ATo is the clear favorite, though A9s gets there on roughly one board in 3. Of every 100 boards, about 10.11 are split pots, and the equity figures already include them.

In the ranking of all 169 starting hands, A9s is number 18 and ATo is number 19.

Boards behind the percentages: 61,642,944 counted in all
HandBoards won, aboutBoards tied, aboutBoards lost, about
A9s16,692,0006,234,00038,717,000
ATo38,717,0006,234,00016,692,000

The board total is exact, 36 deals at 1,712,304 boards each. Won, tied and lost counts are rounded to the nearest thousand from the five-decimal percentages.

A9s against ATo read as odds
HandEquity as odds (to 1)Wins one deal inLoses one deal inPot odds needed to call (to 1)
A9s0.4743.6931.5922.112
ATo2.1121.5923.6930.474

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

If you know the kind of flop that came, the numbers shift: ATo holds 74.48% on rainbow flops topped by a ten or better and 60.10% on low rainbow flops (nine high or lower). ATo stays ahead on all five textures.

A9s against ATo by flop texture, in percent
FlopShare of flopsA9s winsTiesATo winsA9s equity
Rainbow, ten or higher23.90521.2698.51070.22125.524
Rainbow, nine or lower7.04237.8004.20557.99539.902
Two-tone46.52729.0367.08663.87832.579
Monotone5.19232.9207.46759.61336.653
Paired17.33423.73423.64052.62635.554

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

Relative to a random opponent, A9s changes by -30.64 points (baseline 62.78%) and ATo by +5.14 points (baseline 62.72%).

A9s and ATo here compared with each against a random hand, in percent
CaseEquity hereAgainst a random handChange in pointsTimes the random-hand equity
A9s, all flops32.13562.781-30.6460.51186
A9s, rainbow, ten or higher25.52462.781-37.2570.40656
A9s, rainbow, nine or lower39.90262.781-22.8790.63557
A9s, two-tone32.57962.781-30.2020.51893
A9s, monotone36.65362.781-26.1280.58382
A9s, paired35.55462.781-27.2270.56632
ATo, all flops67.86562.722+5.1431.08200
ATo, rainbow, ten or higher74.47662.722+11.7541.18740
ATo, rainbow, nine or lower60.09862.722-2.6240.95816
ATo, two-tone67.42162.722+4.6991.07492
ATo, monotone63.34762.722+0.6251.00996
ATo, paired64.44662.722+1.7241.02749

Does a shared suit matter?

Suit overlap shows up in the numbers. With a suit in common ATo has 68.65% equity, and with none in common it has 67.47%. ATo does better with a shared suit, by 1.18 points.

A9s against ATo by suit overlap, in percent
DealsSpecific dealsShare of dealsA9s winsTiesATo winsA9s equity
Share a suit1233.3326.22610.24063.53431.346
No shared suit2466.6727.50510.04962.44632.530

How often this matchup comes up

Exactly 36 specific deals fit this matchup in one seat order, which is 0.0022% of 1,624,350; both orders together give 72, or 0.0044%.

A worked example

Put $100 each into a $200 pot and deal every board once: ATo averages $135.72 back, ahead of its $100 by $35.72, while A9s averages $64.28, short of its $100 by $35.72.

In 1,000 deals of exactly this matchup, expect about 628 won outright by ATo, about 271 won outright by A9s and about 101 split.

The same matchup from the other side

If you came looking for ATo against A9s, the numbers are the same with the hands swapped: 67.86% and 32.14%.

As9s against AhTd is a ready-made deal for the calculator, with no suit in common between the hands. The neighboring matchups below replace one hand with another of similar strength.

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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