The direct answer: in a fixed preflop all-in between pocket kings (Ks Kh) and pocket jacks (Jd Jc), an exhaustive enumeration of all 1,712,304 possible boards built from the 48 unseen cards gives pocket kings outright wins on 1,381,416 boards (80.6759%), pocket jacks outright wins on 324,786 boards (18.9678%), and leaves 6,102 boards (0.3564%) as ties. Counting half of each tie as equity for both sides, the kings hold 80.8540% equity and the jacks hold 19.1460%. These are exact enumeration results, not estimates, which is why they carry no “about”.

The model behind the numbers

Every equity number needs a declared model, because the answer changes when the model changes. This comparison uses a fixed matchup: one player holds the king of spades and the king of hearts, the other holds the jack of diamonds and the jack of clubs. Four cards are therefore known, so a 52-card deck leaves 48 unseen cards. The enumeration covered every unordered five-card board those 48 cards can produce, 1,712,304 boards in total. Each board was evaluated for the best five-card hand of each side, and the outcome was recorded as a kings win, a jacks win, or a tie. Outright wins, ties, and equity are reported separately: equity adds half of each tie to each side’s outright total.

Two rules of reading follow from this. First, do not quote these percentages for any other king-jack pairing: different suits change which kings and jacks are blocked, and the exact numbers shift with them. Second, the tie share is its own category; folding it silently into one side’s total is a common way hand-matching numbers get misquoted.

Why the gap is this wide

The matchup is dominated: jacks rank below kings, so whenever neither hand improves, the kings win by rank alone. For the jacks to win outright, the board must help them in a way that does not help the kings at least as much: pairing a jack, completing a straight or a flush that favors the jacks’ holding, or producing a better combination for the lower pair specifically.

The kings, by contrast, win on the vast majority of boards where nothing special happens. That asymmetry explains the gap between roughly four wins for the kings and one win for the jacks over five boards. It also explains why pocket jacks is still a strong starting hand in general: its problems come specifically when it runs into the top end of a dominating range, not on every hand it plays.

The tie case

The enumeration found ties on 6,102 of the 1,712,304 boards, about 0.36%. In this fixed matchup, all of those ties play the board: the best five-card hand comes entirely from the community cards, both players use the same five cards, and the pot splits evenly. That result describes this fixed matchup only. In Hold’em, a tie occurs whenever both best five-card hands have equal rank, whether the cards come from the board, the hole cards, or a mix. Suits never break a tie. Board-only outcomes are rare because five random community cards must assemble a straight, a flush, or a similar structure that neither pair improves upon; that rarity is exactly what the small tie percentage measures.

How to read an 80% favorite

An 80.854% equity favorite still loses about one board in five outright. Equity describes the long-run share over many identical matchups, not a promise about a single hand; any single runout can contradict the favorite. That is also why “dominated” does not mean “unbeatable”: the jacks have real ways to end up best by the river, they are just outnumbered.

The practical reading works in the other direction too. If you hold the kings, the number says most boards are yours but a fifth of them are not. If you hold the jacks, the number says most boards go badly but one in five goes well. Neither side gets to treat a preflop all-in as decided before the board arrives.

Three common mistakes

  • Quoting the percentages without the fixed-hands model, which lets them drift onto matchups they were never computed for.
  • Treating the tie share as a win for either side, or ignoring it entirely when adding the numbers up.
  • Calling kings versus jacks unbeatable before the board arrives, which confuses a long-run favorite with a guaranteed outcome.

FAQ

How often do pocket kings beat pocket jacks?

In the exhaustive enumeration of 1,712,304 boards, pocket kings won 1,381,416 boards outright (80.6759%), pocket jacks won 324,786 (18.9678%), and 6,102 boards (0.3564%) split. With ties split evenly, equity is 80.8540% for the kings and 19.1460% for the jacks.

Why is this called a domination matchup?

Because the jacks rank below the kings: the jacks must improve on the board to win most of the time, while the kings stay ahead whenever the jacks do not improve.

When do the two hands tie?

In this fixed matchup, all ties play the board: both players use the same five community cards and the pot splits. In Hold’em generally, a tie means both best five-card hands have equal rank. Suits never break a tie.

Where can I check numbers like this myself?

Use a poker odds chart to see how starting hands sit against each other, or a calculator tool and enter both hands plus a board to reproduce the matchup. You can also leave the community cards empty in a calculator and it will report the preflop model of this article.

This comparison is one of many in our vs series; each page states its model and premises so the numbers mean the same thing every time you read them.

Data Used

  • Deck: standard 52-card deck; hole cards Ks Kh (pocket kings) against Jd Jc (pocket jacks); 48 unseen cards.
  • Algorithm: exhaustive enumeration of all C(48,5) = 1,712,304 unordered five-card boards; each board evaluated for both players’ best five-card hands; outcomes counted as outright wins and ties; equity counted as outright wins plus half of ties.
  • Counts and results (verified 2026-11-06): kings outright 1,381,416 (80.6759%); jacks outright 324,786 (18.9678%); ties 6,102 (0.3564%); equity 80.8540% vs 19.1460%. Counts sum to 1,712,304.