AA vs A9o: preflop equity

Dealt all in against each other, AA takes 93.78% of the pot on average and A9o takes the other 6.22%.

AA

93.78%

Wins 93.09%, ties 1.39%

A9o

6.22%

Wins 5.52%, ties 1.39%

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

AA against A9o: the numbers

Exact preflop results for AA against A9o, in percent
HandWinsTiesLosesEquity
AA93.0881.3885.52493.782
A9o5.5241.38893.0886.218

The matchup pits a pocket pair against an offsuit hand. The non-pair hand shares a rank with the pair, so two of its outs for pairing are blocked by the pair itself.

This is one of the lopsided matchups: A9o wins only 5.52% of the boards outright. The tie share is 1.39%: on those boards the pot is chopped and neither hand wins outright.

Among the 169 starting hands, AA is number 1 and A9o is number 25 by strength against a random hand.

Boards behind the percentages: 61,642,944 counted in all
HandBoards won, aboutBoards tied, aboutBoards lost, about
AA57,382,000856,0003,405,000
A9o3,405,000856,00057,382,000

The total is exact: 36 specific deals times 1,712,304 boards. The three counts are approximate, worked out from the percentages to five decimals and rounded to the nearest thousand.

AA against A9o read as odds
HandEquity as odds (to 1)Wins one deal inLoses one deal inPot odds needed to call (to 1)
AA15.0821.07418.1030.066
A9o0.06618.1031.07415.082

In the last column, a pot-to-call ratio at or above the figure makes a call break even or better at this equity.

Who is ahead on which flops

Rainbow flops topped by a ten or better are the best for AA (95.85%); monotone flops are the worst (84.28%). AA stays ahead on all five textures.

AA against A9o by flop texture, in percent
FlopShare of flopsAA winsTiesA9o winsAA equity
Rainbow, ten or higher23.78295.2161.2713.51395.851
Rainbow, nine or lower7.04291.8522.7475.40193.225
Two-tone46.21593.1491.5315.32093.915
Monotone5.13083.2612.03614.70384.279
Paired17.83193.4050.4526.14393.631

Flop types: rainbow means three different suits, two-tone means one suit twice, monotone means one suit three times, paired means a repeated rank.

Compared with a random hand

The table below sets each hand against its own random-hand baseline: a change of +8.58 points for AA, from 85.20%, and -54.55 for A9o, from 60.77%.

AA and A9o here compared with each against a random hand, in percent
CaseEquity hereAgainst a random handChange in pointsTimes the random-hand equity
AA, all flops93.78285.204+8.5781.10068
AA, rainbow, ten or higher95.85185.204+10.6471.12496
AA, rainbow, nine or lower93.22585.204+8.0211.09414
AA, two-tone93.91585.204+8.7111.10224
AA, monotone84.27985.204-0.9250.98914
AA, paired93.63185.204+8.4271.09890
A9o, all flops6.21860.773-54.5550.10232
A9o, rainbow, ten or higher4.14960.773-56.6240.06827
A9o, rainbow, nine or lower6.77560.773-53.9980.11148
A9o, two-tone6.08560.773-54.6880.10013
A9o, monotone15.72160.773-45.0520.25868
A9o, paired6.36960.773-54.4040.10480

Does a shared suit matter?

Of the deals of this matchup, 24 share a suit (AA at 94.08%) and 12 do not (93.18%). AA does better with a shared suit, by 0.90 points.

AA against A9o by suit overlap, in percent
DealsSpecific dealsShare of dealsAA winsTiesA9o winsAA equity
Share a suit2466.6793.3711.4205.20994.081
No shared suit1233.3392.5221.3256.15393.184

How often this matchup comes up

Counting specific cards, AA 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

Say each player puts $100 in before the flop, making a $200 pot. On average AA takes back $187.56 of it, which is $87.56 more than it put in, and A9o takes back $12.44, $87.56 less than it put in.

Think in thousands: about 931 of 1,000 go to AA, about 55 go to A9o, and about 14 are chopped.

The same matchup from the other side

A9o versus AA is this same page seen from the other hand: 6.22% for A9o, 93.78% for AA.

Try AsAh against Ad9c in the calculator: the hands share no suit, and every card can be changed. The links after it are the closest matchups in the ranking.

How this was computed

All 1,712,304 five-card boards are dealt for every suit pattern among the 36 specific deals of AA against A9o, and both hands are scored on each. That is a full count, so the percentages are exact. Ties are half a win each, and each board appears once per flop it contains.

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

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