March Madness is 68 college basketball teams, six rounds, three weeks, and one of the most compelling tournament formats in sport. Here's how the bracket is put together — and why it produces so many upsets.
The Field: 68 Teams
Of the 68 spots in the tournament:
- 32 automatic bids — each of the 32 Division I conferences sends its champion automatically, regardless of overall record.
- 36 at-large bids — selected by a committee based on record, strength of schedule, and conference performance. Announced on Selection Sunday each March.
The First Four
Four play-in games — called The First Four — are held before the main 64-team bracket begins, played in Dayton, Ohio. These involve:
- The two lowest-ranked at-large teams
- The four lowest-ranked conference champions (two games)
Win and you're in the main bracket. Lose and the season is over without ever appearing in the main draw. It's not a glamorous exit, but it's how the math works out.
Regions and Seeds
The 64-team bracket is divided into four regions: East, West, South, and Midwest. Each has 16 teams seeded 1 through 16. Seeds determine first-round matchups:
- 1 vs 16, 8 vs 9
- 5 vs 12, 4 vs 13
- 6 vs 11, 3 vs 14
- 7 vs 10, 2 vs 15
The 1 vs 16 matchup has produced exactly one upset in the 64-team era — UMBC over Virginia in 2018. The 5 vs 12 matchup is a different story: 12-seeds win roughly 35% of the time. If you're filling out a bracket, always pick at least one 12-seed.
How Regions Are Assigned
Teams aren't placed into regions randomly. The committee follows several rules:
- Teams from the same conference are separated across the bracket where possible, so they can only meet at the Final Four at the earliest.
- Teams can't be placed near their home market in the early rounds — no school should effectively play a home game in the first weekend.
- The #1 overall seed is placed in the region closest to the Final Four host city.
The Final Four
Each region produces one winner over four rounds (Round of 64, Round of 32, Sweet 16, Elite Eight). The four regional champions meet at the Final Four — two semi-finals followed by the National Championship game. Typically held in a large stadium, the Final Four draws 70,000+ fans and is one of the biggest events in American sports.
Why It Produces So Many Upsets
Pure single elimination. No second chances, no aggregate scores. One bad game and a top seed goes home. Combined with the genuine unpredictability of college basketball — more variance in travel, neutral court effects, and less parity among players — the format amplifies upsets rather than smoothing them out.
For community tournament organizers: single elimination, run cleanly, is compelling precisely because it's unforgiving. Every match has stakes. That's worth embracing rather than engineering around.