--- title: "66 vs ATo: preflop equity" url: "https://georgelipoker.com/equity/66-vs-ato.md" canonical_url: "https://georgelipoker.com/equity/66-vs-ato" last_updated: "2026-10-23" type: "reference" summary: "Who is ahead, 66 or ATo? 66 leads 54.30% to 45.70% before the flop, counted exactly over every board, with the split by flop type and suit." related: ["https://georgelipoker.com/equity/66-vs-kjs.md", "https://georgelipoker.com/equity/66-vs-a8s.md", "https://georgelipoker.com/equity/a9s-vs-ato.md"] --- # 66 vs ATo: preflop equity Who is ahead, 66 or ATo? 66 leads 54.30% to 45.70% before the flop, counted exactly over every board, with the split by flop type and suit. Over all 1,712,304 boards that can follow this deal, 66 finishes with 54.30% of the pot and ATo with 45.70%. ## 66 against ATo: the numbers **Exact preflop results for 66 against ATo, in percent** | Hand | Wins | Ties | Loses | Equity | | --- | --- | --- | --- | --- | | 66 | 54.110 | 0.384 | 45.506 | 54.302 | | ATo | 45.506 | 0.384 | 54.110 | 45.698 | 66 is a pocket pair and ATo is an offsuit hand. One hand holds a pair and the other holds two cards that both outrank it, which keeps the equity closer than most people expect. With only 8.60 points between them, the board decides this matchup far more than the cards in hand. About 0.38% of boards chop the pot, which is why equity sits slightly above the win figure for both hands. The hand ranking puts 66 at 17 and ATo at 19 out of 169 starting hands. **Boards behind the percentages: 123,285,888 counted in all** | Hand | Boards won, about | Boards tied, about | Boards lost, about | | --- | --- | --- | --- | | 66 | 66,710,000 | 473,000 | 56,102,000 | | ATo | 56,102,000 | 473,000 | 66,710,000 | 72 specific deals times 1,712,304 boards gives the exact total. The won, tied and lost counts are approximations from the five-decimal percentages, rounded to the nearest thousand. **66 against ATo read as odds** | Hand | Equity as odds (to 1) | Wins one deal in | Loses one deal in | Pot odds needed to call (to 1) | | --- | --- | --- | --- | --- | | 66 | 1.188 | 1.848 | 2.198 | 0.842 | | ATo | 0.842 | 2.198 | 1.848 | 1.188 | 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 Split by what the flop looks like, 66 peaks at 80.45% on low rainbow flops (nine high or lower) and bottoms out at 47.13% on rainbow flops topped by a ten or better. The lead reverses on rainbow flops topped by a ten or better: there ATo is the favorite even though 66 is ahead overall. **66 against ATo by flop texture, in percent** | Flop | Share of flops | 66 wins | Ties | ATo wins | 66 equity | | --- | --- | --- | --- | --- | --- | | Rainbow, ten or higher | 24.717 | 47.030 | 0.201 | 52.769 | 47.131 | | Rainbow, nine or lower | 6.314 | 80.142 | 0.613 | 19.245 | 80.448 | | Two-tone | 46.485 | 53.452 | 0.274 | 46.274 | 53.589 | | Monotone | 5.151 | 50.237 | 1.729 | 48.034 | 51.102 | | Paired | 17.333 | 57.637 | 0.459 | 41.904 | 57.867 | 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 A random hand would give 66 63.29% and ATo 62.72%. Against each other the change is -8.99 points for 66 and -17.02 for ATo. **66 and ATo here compared with each against a random hand, in percent** | Case | Equity here | Against a random hand | Change in points | Times the random-hand equity | | --- | --- | --- | --- | --- | | 66, all flops | 54.302 | 63.285 | -8.983 | 0.85805 | | 66, rainbow, ten or higher | 47.131 | 63.285 | -16.154 | 0.74474 | | 66, rainbow, nine or lower | 80.448 | 63.285 | +17.163 | 1.27120 | | 66, two-tone | 53.589 | 63.285 | -9.696 | 0.84679 | | 66, monotone | 51.102 | 63.285 | -12.183 | 0.80749 | | 66, paired | 57.867 | 63.285 | -5.418 | 0.91439 | | ATo, all flops | 45.698 | 62.722 | -17.024 | 0.72858 | | ATo, rainbow, ten or higher | 52.869 | 62.722 | -9.853 | 0.84291 | | ATo, rainbow, nine or lower | 19.552 | 62.722 | -43.170 | 0.31172 | | ATo, two-tone | 46.411 | 62.722 | -16.311 | 0.73995 | | ATo, monotone | 48.898 | 62.722 | -13.824 | 0.77960 | | ATo, paired | 42.133 | 62.722 | -20.589 | 0.67174 | ## Does a shared suit matter? Looking only at deals where the hands share a suit, 66 has 54.22%; looking only at deals where they do not, 54.71%. 66 does better with no shared suit, by 0.49 points. **66 against ATo by suit overlap, in percent** | Deals | Specific deals | Share of deals | 66 wins | Ties | ATo wins | 66 equity | | --- | --- | --- | --- | --- | --- | --- | | Share a suit | 60 | 83.33 | 54.020 | 0.400 | 45.580 | 54.220 | | No shared suit | 12 | 16.67 | 54.559 | 0.307 | 45.134 | 54.712 | ## How often this matchup comes up Out of 1,624,350 ways to deal two seats two cards each, 72 are 66 in one seat and ATo in the other (0.0044%); with the seats swapped too, 144 (0.0089%). ## A worked example Take a $200 pot built from $100 each. 66's equity of 54.30% is worth $108.60, a $8.60 edge, and ATo's 45.70% is worth $91.40, which is $8.60 under its stake. Think in thousands: about 541 of 1,000 go to 66, about 455 go to ATo, and about 4 are chopped. ## The same matchup from the other side The mirror image, ATo against 66, is 45.70% to 54.30%, and its address redirects to this page. ## Keep exploring The calculator link fills in 6s6h against AdTc, 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. - [Open 6s6h against AdTc in the equity calculator](https://georgelipoker.com/tools/equity-calculator.md#p1=6s6h&p2=AdTc) - [66 combos](https://georgelipoker.com/combos/66.md) - [ATo combos](https://georgelipoker.com/combos/ato.md) - [66 vs KJs](https://georgelipoker.com/equity/66-vs-kjs.md) - [66 vs A8s](https://georgelipoker.com/equity/66-vs-a8s.md) - [A9s vs ATo](https://georgelipoker.com/equity/a9s-vs-ato.md) - [All hand matchups](https://georgelipoker.com/equity.md) ## How this was computed Each figure is a complete count over boards. Take the 72 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. ## Related - [66 vs KJs: preflop equity](https://georgelipoker.com/equity/66-vs-kjs.md) - [66 vs A8s: preflop equity](https://georgelipoker.com/equity/66-vs-a8s.md) - [A9s vs ATo: preflop equity](https://georgelipoker.com/equity/a9s-vs-ato.md)