How NFL Playoff Expansion Lengthened the Path

A perfect season is a moving target, and it has moved in one direction: harder. Over the last five decades, the NFL has repeatedly lengthened the road between a team and a flawless finish — more regular-season games, more playoff teams, more rounds. Here’s how each expansion pushed the number from seventeen wins toward twenty.

1970: the merger and the birth of the wild card

When the AFL and NFL merged in 1970, the postseason expanded to eight teams — four from each conference. Crucially, this is when the wild card arrived: for the first time, a team that hadn’t won its division could still make the playoffs. The bracket that a perfect season had to survive suddenly had more teams in it, and the idea of a non-division-winner crashing the party was born.

1978: a longer season and another round

Two changes landed around this era that reshaped the math. The regular season expanded to sixteen games, and the playoff field grew to ten teams — five per conference — adding a second wild card on each side. More regular-season games meant more chances to lose before the playoffs even started, and a bigger field meant one more layer of good teams standing between a contender and the Super Bowl. Across this whole 16-game era, a perfect season was nineteen wins.

1990: twelve teams and the two-bye format

In 1990, the playoffs expanded again, to twelve teams — six per conference. This is the format many fans grew up with: three division winners and three wild cards per side, with the top two seeds in each conference earning first-round byes. The field was now large enough that surviving it required beating a deep bench of quality opponents, and the reward for a great regular season was a bye that skipped exactly one round.

2002: realignment reshapes the seeds

A structural change rather than a size change: in 2002 the league realigned into eight divisions, four per conference. The field stayed at twelve, but now it was four division winners and two wild cards per side. The seeding logic that governs a perfect season’s path — win your division, earn a high seed, chase the bye — took the shape it still largely has today.

2020: fourteen teams and a single bye

The most recent playoff expansion pushed the field to fourteen teams, seven per conference, and cut the number of byes to just one per side — the #1 seed. This made the top seed dramatically more valuable and everything below it more crowded, since six of seven teams in each conference now had to play on Wild Card weekend. It’s the format the game’s whole premise is built on, and we explain it in full in our breakdown of the real NFL playoff format. For why that single remaining bye matters so much, see our guide to the first-round bye advantage.

2021: the 17th game

Finally, in 2021 the regular season grew from sixteen games to seventeen — the first change to its length in more than four decades. That added one more win to the requirement and turned the perfect-season number into the one this game is named for: twenty. We lay out that exact arithmetic in our guide to what a 20-0 season actually requires today.

The cumulative effect

Line the changes up and the trend is unmistakable. Every expansion added games, opponents, or both between a team and a perfect finish:

• 14-game era (through 1977): perfect season was 17-0. The 1972 Dolphins did it.
• 16-game era (1978–2020): perfect season was 19-0. No one did it.
• 17-game era (2021–present): perfect season is 20-0. No one has yet.

The number didn’t climb because teams got worse. It climbed because the road kept getting longer, and the sport kept adding hurdles. That’s a big part of why only one team has ever finished the job — a story we tell in full in our look at why only one team ever finished perfect. Each expansion was good for the league and its fans. It was also, quietly, one more reason a perfect season keeps slipping further out of reach.