AA vs JJ: what are the odds?

Jacks have a bad reputation, but against aces they do fractionally better than queens or kings do. The reason is small and real: a jack is more likely to be part of straight runouts than a king is, so JJ picks up a few extra winning boards. It does not change the story. Any pair against a bigger pair is around a 4-to-1 underdog, and the only question is whether you could have found the fold preflop. Against most opponents, with jacks, you could not.

Quick tip: Jacks lose to three bigger pairs, but they are still a top-five starting hand. Do not let this matchup scare you off playing them hard.

All numbers are all-in preflop equity vs one opponent, computed by the Poker Shark equity engine from the full 169 by 169 hand matrix, weighted across suited and offsuit combos.