What Is March Madness? A Guide to the NCAA Tournament and Brackets

Even if you’ve never watched a college basketball game in your life, there’s a good chance you’ve been asked at some point if you wanted to fill out a March Madness bracket. It’s an annual obsession in the United States.

Studies have found that literally tens of billions of dollars in productivity are lost every March, as early-round, early-afternoon games of the NCAA college basketball tournament soak up attention around the country that’s otherwise supposed to be reserved for filling out those "TPS reports" — not brackets.

Tournament games are exhilarating to watch, but it’s the game within the game — filling out and rooting for your bracket picks — that makes us all go bananas for a few weeks every March.

Because of how wildly unpredictable college hoops can be, there’s a decent chance that Carol from H.R. who doesn’t follow the sport in the slightest and fills out her bracket based on mascots or jersey colors will end up doing better than someone who eats, sleeps and breathes college basketball for five months every year.

But if March Madness is a new concept to you, or you’re just interested in learning a bit more about the background and history of this yearly phenomenon, allow us to guide you into the Madness.

Disclaimer: Our focus here is on the Division I men’s NCAA tournament. There are other D-I men’s tournaments, along with D-II, D-III and NAIA tournaments. "March Madness" also applies to the women’s D-I NCAA tournament, which continues to grow in stature and has moved away from being the UConn Invitational, with Dawn Staley’s South Carolina taking the baton as the nation’s preeminent program.

How Is the Bracket Built? And What Is Bracketology?

Unlike the NBA playoffs, where everything is based on records and predetermined tiebreakers and nothing is open to debate, no college basketball team knows for sure if or where it will land in the NCAA tournament field until it everything gets announced on Selection Sunday.

The Selection Committee

Before you can fill out a March Madness bracket, the NCAA tournament selection committee has to build it by determining which teams get in and where they should be seeded.

The selection committee is a group of 12 individuals who are otherwise employed as athletic directors or conference commissioners throughout the country. Members serve (up to) five-year terms on the committee, meaning it ends up being a slightly different group every year.

How the Field Is Decided 

The committee awards a little less than half of the 68 total spots in the March Madness field to automatic bids. These spots are determined during "Championship Week," which is the 10 or so days of pre-Madness insanity when each conference (Big Ten, Big East, ACC, etc.) holds its own league tournament to decide who will become its automatic representative in the Big Dance.

For the rest of the field, it’s up to the selection committee to decide the best and most deserving teams for at-large bids, which are invited based on a combination of schedule strength, record quality, scoring margin and enough metrics to make your head spin.

Seeding and Matchups

Selecting the field is only half the battle, though. The committee simultaneously needs to rank the teams from best to worst to determine what seed they will get in the bracket. The four No. 1 seeds, for instance, are the four teams deemed best- and most- deserving of being in the tournament. The No. 16 seeds…not so much. They’re always the conference tournament winners perceived to be the weakest qualifiers.

Once the seed list is set, the bracket is built in such a way as to not violate any of the bracketing principles and procedures for when in the NCAA tournament that regular-season rematches are allowed to occur. Beyond those principles, bracketing is primarily based on geography.

The committee spends several days during Championship Week voting and debating before the final product is revealed on Selection Sunday. 

What About Bracketology?

If you’ve never heard of bracketology, it's the art of forecasting throughout the regular season what the selection committee’s bracket will be on Selection Sunday.

Bracketology has nothing to do with predicting how the tournament will play out, though. Speaking as someone who has been doing bracketology for well over a decade, we’re generally pretty good at projecting the field, but mostly as bad as anyone else at predicting who actually wins each matchup.

How Does March Madness Work?

Once the bracket is set, let the single-elimination carnage begin!

Beginning just 48 hours after the Selection Show, it takes a little less than three weeks to whittle the field of 68 teams down to the Final Four and then a singular national champion.

The First Four

The First Four (or first round) takes place in Dayton, Ohio, with two games on each of Tuesday and Wednesday. The teams partaking in that amuse-bouche are the four lowest-seeded teams who earned at-large bids (usually No. 11 seeds, though not necessarily) and the four lowest-seeded teams who earned automatic bids (always No. 16 seeds).

Those initial contests used to be known as the "play-in games," but the NCAA didn’t appreciate the implication that those eight teams weren’t actually part of the tournament until they won those games. "First Four" was something of a compromise after the NCAA confusingly tried to change the naming of the first few rounds from 2011-15.

The True Madness

After the First Four tips things off, it’s time for the four maddest days of madness with 16 games on Thursday, 16 more Friday and eight apiece on Saturday and Sunday. Just like that, the tournament field goes from 64 teams down to just 16 in a whirlwind of upsets, wild comebacks and, with any luck, a few buzzer-beaters and overtime thrillers.

For those two rounds, games are played on eight neutral sites that change on an annual basis — four Thursday/Saturday pods and four Friday/Sunday pods.

Down to the Elite Eight, Final Four and National Champion

After that, there’s a few days to catch our breath and then it’s on to the Sweet 16 and the Elite Eight, which are played out over the following Thursday through Sunday. These are the East, Midwest, South and West regionals, with these sites also changing on an annual basis.

Then it all comes down to the Final Four and national championship games the following Saturday and Monday at another rotating site.

March Madness History

The first NCAA men’s basketball tournament was held in 1939 and was won by the University of Oregon.

Back then, there were only eight teams in the tournament field. It doubled in size to 16 teams in 1951 and varied from 22-25 teams for about two decades before expanding to 32 teams in 1975. Four years later, it was 40 teams and 48 the year after that. The big jump to 64 teams came in 1985, with only slight additions since then, to 65 teams in 2001 and 68 in 2011.

The ever-increasing size of the field gives testament to the enduring popularity and near-unquenchable thirst for more Madness. But is there a limit to how big the tournament should be?

For more than a decade, the topic of further expansion has been a hotly debated issue, and it’s feeling inevitable that it will be coming. Whether it’s a move to 72, 80, 96 or even 128 teams remains to be seen, but here’s hoping the impending money grab doesn’t ruin the greatest tournament in sports.

Kings of March

As far as who’s best at March Madness, Kentucky has competed in the most NCAA tournaments (61) and North Carolina has made the most Final Fours (21), but it’s UCLA with the most national championships. All but one of the Bruins’ 11 titles came under John Wooden’s tutelage from 1964-75, and no one has been able to catch up since.

A total of 37 schools have won at least one national championship, with 15 claiming multiple natties. (Fun fact: Oregon has not even played in a national championship game since winning the first one.)

In the 64-teams-or-more era of the tournament, though, the Connecticut Huskies reign supreme with six national championships. All of UConn’s titles have come since 1999, including the improbable back-to-back run in 2023 and 2024. (UConn has also won 11 women’s tournaments since 1995.)

See also: College Basketball Blue Bloods

What Is Sleeper Bracket Mania?

The worst-kept secret in sports entertainment is that people get hopelessly obsessed with March Madness every year because of the bracket pools.

There are a bunch of different ways to get yourself invested in the Madness, but the tried and true approach is filling out a bracket before the round of 64 begins on Thursday and proceeding to live and die with each result over the next few days and weeks.

In the old days, you’d carry around a paper copy of your bracket along with two highlighters — a nice yellow or green one for marking correct picks, and an ominous red one for marking your misses.

Nowadays, though, all you need is the Sleeper app on your phone.

With Sleeper’s Bracket Mania game, you’ll get to read blurbs about each of the teams in the tournament field, in case you need any stats, help or just the occasional chuckle while filling out your bracket.

Once the tournament has begun and entries are locked in, Sleeper takes care of marking all those winners and losers while you use the in-app chat for bragging rights and/or sob stories about where it all went wrong. You can also follow along each game for the latest twist and turn in your bracket fortunes.

You can have up to 10,000 participants in your bracket pool, or make it private and just keep it to a small group of friends. Either way, you can see throughout the tournament where your bracket ranks globally.

Frequently Asked Questions

Why is the NCAA Tournament called March Madness?

In addition to the fact that it is always predominantly held in March and always insanely unpredictable, legendary broadcaster Brent Musburger was credited with bringing that nomenclature to the sport in 1982.

What are the odds of filling out a perfect bracket?

Mathematically speaking, if you assume every game is a coin flip and you don’t have to pick the First Four games, the odds are 1 divided by 2 to the 63rd power, or 1-in-9,223,372,036,854,775,808.

That’s 9.2 quintillion for those keeping score at home, and it’s a practically unfathomable number. So, you know, don’t get your hopes up. Just picking the correct champion is difficult enough. Nailing every other game along the way is effectively impossible.

What was the biggest Cinderella to win March Madness?

That crown belongs to Villanova, which won it all as a No. 8 seed in 1985.

Surprisingly, though, there have been six No. 11 seeds that have reached the Final Four, including both 2011 VCU and 2021 UCLA making the improbable run from First Four to Final Four.

There has yet to ever be a double-digit seed in the national championship game, though.

Has a No. 16 Seed ever upset a No. 1 Seed?

Yes. Twice, in fact, with the University of Maryland Baltimore County (UMBC) stunning Virginia in 2019 and Fairleigh Dickinson (FDU) toppling Purdue in 2023.

Neither No. 16 seed managed to win its subsequent game, though, so we are still waiting for the first instance of a No. 16 in the Sweet 16.

Join the Madness with Sleeper’s Bracket Mania

If you’re ready to get in on the March Madness hysteria, download the Sleeper App and set up a Bracket Mania pool with your friends. You'll have to wait until the bracket is announced to start, of course.

Since March Madness only encompasses a small fraction of the calendar, Sleeper has you covered year-round with a multitude of fantasy offerings across other sports.