ATo vs A8s: preflop equity

If ATo and A8s get all the chips in before the flop, ATo owns 67.58% of the pot in the long run and A8s owns 32.42%.

ATo

67.58%

Wins 62.50%, ties 10.15%

A8s

32.42%

Wins 27.35%, ties 10.15%

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

ATo against A8s: the numbers

Exact preflop results for ATo against A8s, in percent
HandWinsTiesLosesEquity
ATo62.50310.14727.35067.577
A8s27.35010.14762.50332.423

ATo and A8s 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.

ATo is well ahead, and A8s needs a specific kind of board to catch up. The tie share is 10.15%: on those boards the pot is chopped and neither hand wins outright.

Place 19 of 169 belongs to ATo and place 21 belongs to A8s in the ranking against a random hand.

Boards behind the percentages: 61,642,944 counted in all
HandBoards won, aboutBoards tied, aboutBoards lost, about
ATo38,529,0006,255,00016,859,000
A8s16,859,0006,255,00038,529,000

Exact total: 36 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 A8s read as odds
HandEquity as odds (to 1)Wins one deal inLoses one deal inPot odds needed to call (to 1)
ATo2.0841.6003.6560.480
A8s0.4803.6561.6002.084

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

Rainbow flops topped by a ten or better are the best for ATo (74.30%); low rainbow flops (nine high or lower) are the worst (58.97%). ATo stays ahead on all five textures, but the swing between them is large, so how the flop looks matters a great deal.

ATo against A8s by flop texture, in percent
FlopShare of flopsATo winsTiesA8s winsATo equity
Rainbow, ten or higher23.90570.0308.54921.42174.304
Rainbow, nine or lower7.04256.9044.13438.96258.971
Two-tone46.52763.5297.10529.36667.082
Monotone5.19259.4037.49233.10563.149
Paired17.33452.57323.75623.67164.451

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

Each hand has a baseline against a random hand: 62.72% for ATo, 61.94% for A8s. Here the change is +4.86 and -29.52 points.

ATo and A8s here compared with each against a random hand, in percent
CaseEquity hereAgainst a random handChange in pointsTimes the random-hand equity
ATo, all flops67.57762.722+4.8551.07741
ATo, rainbow, ten or higher74.30462.722+11.5821.18466
ATo, rainbow, nine or lower58.97162.722-3.7510.94020
ATo, two-tone67.08262.722+4.3601.06951
ATo, monotone63.14962.722+0.4271.00681
ATo, paired64.45162.722+1.7291.02757
A8s, all flops32.42361.944-29.5210.52342
A8s, rainbow, ten or higher25.69661.944-36.2480.41483
A8s, rainbow, nine or lower41.02961.944-20.9150.66236
A8s, two-tone32.91861.944-29.0260.53142
A8s, monotone36.85161.944-25.0930.59491
A8s, paired35.54961.944-26.3950.57389

Does a shared suit matter?

Two kinds of deal exist here. In 12 of them the hands share a suit and ATo holds 68.36%. In 24 they do not, and it holds 67.18%. ATo does better with a shared suit, by 1.18 points.

ATo against A8s by suit overlap, in percent
DealsSpecific dealsShare of dealsATo winsTiesA8s winsATo equity
Share a suit1233.3363.22510.27526.50068.363
No shared suit2466.6762.14210.08427.77467.184

How often this matchup comes up

This page stands for 36 specific-card matchups (0.0022% of 1,624,350 ordered deals), or 72 once you count the seats both ways (0.0044%).

A worked example

Put $100 each into a $200 pot and deal every board once: ATo averages $135.16 back, ahead of its $100 by $35.16, while A8s averages $64.84, short of its $100 by $35.16.

Over a long run, 1,000 deals split into about 625 for ATo, 274 for A8s and 101 tied.

The same matchup from the other side

A8s versus ATo is this same page seen from the other hand: 32.42% for A8s, 67.58% for ATo.

The calculator link fills in AsTh against Ad8d, 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.

How this was computed

The page is built from a full enumeration: 1,712,304 boards, every suit pattern of the 36 specific deals, both seven-card hands evaluated. A tie is worth half a win to each hand, and a board is tallied under each of its ten possible flops for the texture rows.

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

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