What is the First Four in the NCAA tournament?

A preliminary round played by 8 of the tournament's 68 teams — the four lowest-seeded automatic bids and four last at-large selections — before the main 64-team bracket is set. The four winners join the field as the final teams in their seed lines.

Where do most March Madness upsets actually happen?

Concentrated in the middle seeds. A 12-seed beating a 5-seed is common enough to be a known bracket pattern, while 13-, 14-, 15- and 16-seed wins are historically rare, so the realistic upset zone sits in the middle of the seed range, not at the extremes.

How is a bracket pool different from a sportsbook bet on March Madness?

A bracket pool rewards picking upsets other people missed, since your score is relative to the whole field. A sportsbook bet prices that same game directly into its own odds, independent of what anyone else picked, so it's a pure read on that one matchup rather than a contrarian play against a pool.

March Madness bracket betting explained (seeding, upset odds & bracket pools vs. sportsbook bets)

Last updated: 2026-07-30 · Written by Priya Nair

The NCAA men's basketball tournament starts with a field of 68 teams announced on Selection Sunday, and almost everything about how the bracket is bet on flows from one number: each team's seed, 1 through 16, in its region. Understanding what that seed actually represents, and how a bracket pool differs structurally from a sportsbook bet, is the foundation for reading March Madness betting correctly.

From 68 teams to 64: the First Four

Eight of the tournament's 68 teams — the four lowest-seeded automatic conference-tournament winners and the four last at-large selections — play a preliminary round called the First Four before the main bracket even begins. Once those eight teams are cut down to four winners, the true 64-team field is set, split into four regions of 16 seeded teams each, and the standard single-elimination bracket everyone recognizes actually starts.

Why the seed number does most of the work

A team's seed (1 through 16 in its region) is a direct ranking of expected strength, and it drives both the bracket structure and the betting odds long before any specific matchup is analyzed. A 1-seed plays a 16-seed in round one specifically because that's the widest possible talent gap the bracket can create, and historically the 1-seeds have advanced past that round with near-total reliability — the seed alone tells most of the story for the top of the bracket, which is why 1-through-4 seeds are treated as safe advances in most brackets and betting markets alike.

How upset likelihood actually changes by seed matchup

Upset frequency isn't uniform across the bracket — it's heavily concentrated in the middle seeds rather than spread evenly. A 12-seed beating a 5-seed happens often enough that it's a well-known bracket trope, while a 13-, 14-, 15- or 16-seed actually winning is rare enough that only a handful of such upsets have ever happened across the tournament's entire modern history. This is the practical takeaway for betting the bracket: the realistic upset zone sits in the middle seeds, not at the extremes, even though a low-seed upset gets far more attention when it happens.

Bracket pools vs. sportsbook bets: a genuinely different wager

A bracket pool and a sportsbook bet on the same tournament are structurally different bets, not just different formats. In a bracket pool, correctly picking a lower-seeded upset winner is worth more than picking the favorite precisely because most of the field picked the favorite — the value comes from being right when others are wrong, similar in spirit to fading the public explained. A sportsbook bet, by contrast, prices that same upset directly into the odds or point spread for that specific game, independent of what anyone else in a pool picked. Betting a specific upset at a sportsbook is a pure read on that one matchup; picking it in a bracket pool is also a bet on being contrarian relative to the field.

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FAQ

What is the First Four in the NCAA tournament? A preliminary round played by 8 of the tournament's 68 teams — the four lowest-seeded automatic bids and four last at-large selections — before the main 64-team bracket is set. The four winners join the field as the final teams in their seed lines.
Where do most March Madness upsets actually happen? Concentrated in the middle seeds. A 12-seed beating a 5-seed is common enough to be a known bracket pattern, while 13-, 14-, 15- and 16-seed wins are historically rare, so the realistic upset zone sits in the middle of the seed range, not at the extremes.
How is a bracket pool different from a sportsbook bet on March Madness? A bracket pool rewards picking upsets other people missed, since your score is relative to the whole field. A sportsbook bet prices that same game directly into its own odds, independent of what anyone else picked, so it's a pure read on that one matchup rather than a contrarian play against a pool.

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