List of formations in American football

The following is a list of common and historically significant formations in American football. In football, the formation describes how the players in a team are positioned on the field. Many variations are possible on both sides of the ball, depending on the strategy being employed. On offense, the formation must include at least seven players on the line of scrimmage and a center to start the play by snapping the ball. There are no restrictions on the arrangement of defensive players.

This list is not exhaustive; there are hundreds of different ways to organize a team's players while still remaining within the "7 on the line 4 in the backfield" convention. Still, this list of formations covers enough of the basics that almost every formation can be considered a variant of the ones listed below.

The T formation is the precursor to most modern formations in that it places the quarterback directly under center (in contrast to its main competitor of its day, the single wing, which had the quarterback receiving the ball on the fly).

It consists of three running backs lined up in a row about five yards behind the quarterback, forming the shape of a T. It may feature two tight ends (known as the Power T) or one tight end and a wide receiver (in this case known as a split end). When legendary coach George Halas' Chicago Bears used the T-formation to defeat the Washington Redskins by a score of 73–0 in the 1940 NFL championship game, it marked the end of the single wing at nearly all levels of play, as teams, over the course of the 1940s, moved to formations with the quarterback "under center" like the T. George Halas is credited with perfecting the T formation.

One variation of the T Formation would be where all the running backs would be closer than usual, being at fullback depth rather than halfback depth. Another variation of the "balanced T" formation is the so-called "unbalanced T" formation. In this configuration the line of scrimmage has an end and tackle left of center, while to the right of the center are two guards a tackle and an end. This creates a line that is weighted toward the right of the center. With the backfield lining up in the conventional T formation behind the center (quarterback, two halfbacks and fullback), the resulting configuration is "unbalanced" due the asymmetry of the placement of the linemen. The "split T" spreads the offensive line out over almost twice as much ground compared to the conventional T formation. This causes the defensive line to also spread out, creating gaps the offense can exploit.

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