A9o vs A5s: preflop equity

The exact count puts A9o at 63.45% and A5s at 36.55% when the two hands see all five board cards.

A9o

63.45%

Wins 56.00%, ties 14.90%

A5s

36.55%

Wins 29.10%, ties 14.90%

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

A9o against A5s: the numbers

Exact preflop results for A9o against A5s, in percent
HandWinsTiesLosesEquity
A9o56.00414.89929.09763.454
A5s29.09714.89956.00436.546

A9o and A5s are an offsuit hand and a suited hand, in that order. Because the hands share one rank, the one with the higher kicker is ahead when that rank pairs and the other hand is mostly drawing.

That is a modest edge, the kind that shows up over many hands and is easy to miss in one. Ties are 14.90% of the outcomes here; each tied board gives both hands half the pot.

Ranked by equity against a random hand, A9o is number 25 of the 169 starting hands and A5s is number 30.

Boards behind the percentages: 61,642,944 counted in all
HandBoards won, aboutBoards tied, aboutBoards lost, about
A9o34,523,0009,184,00017,936,000
A5s17,936,0009,184,00034,523,000

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.

A9o against A5s read as odds
HandEquity as odds (to 1)Wins one deal inLoses one deal inPot odds needed to call (to 1)
A9o1.7361.7863.4370.576
A5s0.5763.4371.7861.736

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

Across the five flop textures A9o's equity moves by 7.60 points, from 60.09% on paired flops to 67.69% on rainbow flops topped by a ten or better. A9o stays ahead on all five textures.

A9o against A5s by flop texture, in percent
FlopShare of flopsA9o winsTiesA5s winsA9o equity
Rainbow, ten or higher24.58860.62314.12725.25067.687
Rainbow, nine or lower6.36059.9243.40136.67561.624
Two-tone46.52757.46811.20431.32863.070
Monotone5.19255.03210.59834.37060.331
Paired17.33344.37931.41624.20560.087

Read the flop types this way: rainbow has three suits, two-tone has two cards of one suit, monotone has three, and paired repeats a rank.

Compared with a random hand

Compared with a random opponent, this matchup shifts A9o from 60.77% by +2.68 points and A5s from 59.92% by -23.37 points.

A9o and A5s here compared with each against a random hand, in percent
CaseEquity hereAgainst a random handChange in pointsTimes the random-hand equity
A9o, all flops63.45460.773+2.6811.04411
A9o, rainbow, ten or higher67.68760.773+6.9141.11377
A9o, rainbow, nine or lower61.62460.773+0.8511.01400
A9o, two-tone63.07060.773+2.2971.03780
A9o, monotone60.33160.773-0.4420.99273
A9o, paired60.08760.773-0.6860.98871
A5s, all flops36.54659.923-23.3770.60988
A5s, rainbow, ten or higher32.31359.923-27.6100.53924
A5s, rainbow, nine or lower38.37659.923-21.5470.64042
A5s, two-tone36.93059.923-22.9930.61629
A5s, monotone39.66959.923-20.2540.66200
A5s, paired39.91359.923-20.0100.66607

Does a shared suit matter?

When the hands share a suit, A9o holds 64.22%; when they do not, it holds 63.07%. A9o does better with a shared suit, by 1.15 points.

A9o against A5s by suit overlap, in percent
DealsSpecific dealsShare of dealsA9o winsTiesA5s winsA9o equity
Share a suit1233.3356.69315.05628.25164.221
No shared suit2466.6755.66014.82029.52063.070

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

To see what the equity is worth, imagine $100 each in a $200 pot. A9o is worth $126.90 on average (+$26.90); A5s is worth $73.10 (-$26.90).

Run 1,000 deals and the tally comes out near 560 for A9o, 291 for A5s and 149 ties.

The same matchup from the other side

The mirror image, A5s against A9o, is 36.55% to 63.45%, and its address redirects to this page.

As9h against Ad5d 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

Each figure is a complete count over boards. Take the 36 specific deals, group them by suit pattern, deal all 1,712,304 boards against each, and compare the two seven-card hands. Equity counts a tie as half a win; the flop rows use every one of a board's ten flops.

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

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