ATo vs A3s: preflop equity

If ATo and A3s get all the chips in before the flop, ATo owns 66.64% of the pot in the long run and A3s owns 33.36%.

ATo

66.64%

Wins 61.45%, ties 10.38%

A3s

33.36%

Wins 28.17%, ties 10.38%

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

ATo against A3s: the numbers

Exact preflop results for ATo against A3s, in percent
HandWinsTiesLosesEquity
ATo61.45310.38128.16666.643
A3s28.16610.38161.45333.357

ATo is an offsuit hand and A3s is a suited hand. The two hands share a rank, and the one with the better other card dominates: it wins most kicker battles when that shared rank hits.

ATo is the clear favorite, though A3s gets there on roughly one board in 3. Split pots make up 10.38% of the boards, and both equity figures count them as half a win each.

The hand ranking puts ATo at 19 and A3s at 38 out of 169 starting hands.

Boards behind the percentages: 61,642,944 counted in all
HandBoards won, aboutBoards tied, aboutBoards lost, about
ATo37,881,0006,399,00017,362,000
A3s17,362,0006,399,00037,881,000

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.

ATo against A3s read as odds
HandEquity as odds (to 1)Wins one deal inLoses one deal inPot odds needed to call (to 1)
ATo1.9981.6273.5500.501
A3s0.5013.5501.6271.998

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

Across the five flop textures ATo's equity moves by 18.00 points, from 55.68% on low rainbow flops (nine high or lower) to 73.68% on rainbow flops topped by a ten or better. 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 A3s by flop texture, in percent
FlopShare of flopsATo winsTiesA3s winsATo equity
Rainbow, ten or higher23.90569.3428.68121.97773.682
Rainbow, nine or lower7.04253.5884.18242.23055.679
Two-tone46.52762.3657.24330.39265.986
Monotone5.19258.6587.67333.66962.495
Paired17.33452.15824.47523.36764.396

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

Each hand has a baseline against a random hand: 62.72% for ATo, 58.22% for A3s. Here the change is +3.92 and -24.86 points.

ATo and A3s here compared with each against a random hand, in percent
CaseEquity hereAgainst a random handChange in pointsTimes the random-hand equity
ATo, all flops66.64362.722+3.9211.06251
ATo, rainbow, ten or higher73.68262.722+10.9601.17474
ATo, rainbow, nine or lower55.67962.722-7.0430.88771
ATo, two-tone65.98662.722+3.2641.05204
ATo, monotone62.49562.722-0.2270.99638
ATo, paired64.39662.722+1.6741.02669
A3s, all flops33.35758.220-24.8630.57295
A3s, rainbow, ten or higher26.31858.220-31.9020.45204
A3s, rainbow, nine or lower44.32158.220-13.8990.76127
A3s, two-tone34.01458.220-24.2060.58423
A3s, monotone37.50558.220-20.7150.64419
A3s, paired35.60458.220-22.6160.61154

Does a shared suit matter?

Two kinds of deal exist here. In 12 of them the hands share a suit and ATo holds 67.45%. In 24 they do not, and it holds 66.24%. ATo does better with a shared suit, by 1.21 points.

ATo against A3s by suit overlap, in percent
DealsSpecific dealsShare of dealsATo winsTiesA3s winsATo equity
Share a suit1233.3362.19210.51227.29667.448
No shared suit2466.6761.08310.31528.60266.241

How often this matchup comes up

Out of 1,624,350 ways to deal two seats two cards each, 36 are ATo in one seat and A3s in the other (0.0022%); with the seats swapped too, 72 (0.0044%).

A worked example

Worked example: both players commit $100, so $200 sits in the middle. Over every board, ATo's average share is $133.28 (a gain of $33.28) and A3s' is $66.72 (a loss of $33.28).

In 1,000 deals of exactly this matchup, expect about 614 won outright by ATo, about 282 won outright by A3s and about 104 split.

The same matchup from the other side

A3s versus ATo is this same page seen from the other hand: 33.36% for A3s, 66.64% for ATo.

AsTh against Ad3d 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

This is an exact count with no sampling. For the 36 ways to deal one ATo and one A3s without reusing a card, grouped by suit pattern, every one of the 1,712,304 possible boards is dealt and both seven-card hands are compared. A tie counts as half a win in the equity column, and each board is counted once under each of its ten three-card flops.

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

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