4-3 Defense

The 4-3 puts four linemen up front, three linebackers behind them and four defensive backs, and it is the classic early-down base defense.

Tip: Count the X's crouched at the line: four up front with three linebackers stacked behind them points to a 4-3.

How to Spot It

In cover0, a front is named by personnel, meaning who is on the field. Exact alignment doesn't change the name. A 4-3 has four down linemen (players who start in a crouch with a hand on the ground), three linebackers and four defensive backs (the cornerbacks and safeties who cover passes). Your job is to count each group from the X's.

Start at the line of scrimmage. Look for four X's tight to the ball: two tackles inside, near the center and guards, and two ends just outside the offensive tackles. Then look four or five yards deeper for a row of three X's. That second row is the giveaway. Three defenders standing in the box, the area between the offensive tackles and about five yards deep, usually means a 4-3.

Finish with the back end. Two cornerbacks usually line up across from the widest receivers, and two safeties sit deeper, often 10 yards or more off the ball. If you spot a third cornerback over a slot receiver (the inside receiver, lined up between the widest receiver and the line), check the linebacker row again. Five defensive backs with only two linebackers makes it Nickel.

When Teams Use It

The 4-3 is a base defense, the group a team starts with on early downs. Coaches like it against heavier offensive personnel, such as two running backs or two tight ends, when a run is likely and a third linebacker helps fill gaps. First-and-10 against a fullback and a tight end is a natural 4-3 moment.

When the offense sends out three wide receivers, most teams swap a linebacker for a fifth defensive back. That is why the 4-3 appears less often than its fame suggests. In the plays cover0 draws from, it was 15.4% of labeled snaps in 2016 and about 11% in 2025.

History

The 4-3 grew up with the New York Giants in the 1950s. In 1950, head coach Steve Owen used his umbrella defense, with four defensive backs spread deep like the spokes of an umbrella, to contain the pass-heavy Cleveland Browns. Football historians have called it a forerunner of the 4-3.

Tom Landry, a Giants defensive back who became the team's defensive coach, took the next step. He built a 4-3 with four linemen up front and a middle linebacker standing behind them, a role that fit the quick, mobile Sam Huff. Huff, a rookie, took over in the middle in October 1956, and that season the Giants beat the Chicago Bears 47-7 for the NFL title.

The 4-3 shared the league with the 3-4 from the mid-1970s on. Its biggest change came from offenses. As teams spread out with three or more receivers, defenses answered with extra defensive backs. By 2015, Pro Football Focus counted five or more defensive backs on 63.4% of snaps. Today the 4-3 is mostly an early-down package.

Coaches Known for It

Steve Owen. Coached the New York Giants from 1930 to 1953. His umbrella defense, built on four deep defensive backs, slowed the pass-heavy Cleveland Browns in 1950 and is seen as a forerunner of the 4-3.

Tom Landry. Built the Giants' 4-3 around middle linebacker Sam Huff in the mid-1950s. As the Dallas Cowboys' first head coach (1960 to 1988), he added the Flex, his own 4-3 variation, in the 1960s and won Super Bowls VI and XII.

Monte Kiffin. Tampa Bay's defensive coordinator from 1996 to 2008, he and head coach Tony Dungy built the Tampa 2, a 4-3 scheme whose middle linebacker runs deep down the middle on passes. His 2002 defense allowed the fewest points in the league, and the Buccaneers won the Super Bowl that season.

How Often It's Used

Share of the plays cover0 could label each season.

Season	Share
2016	15.4%
2017	18.1%
2018	18.4%
2019	15.4%
2020	14.1%
2021	11.7%
2022	10.3%
2023	8.3%
2024	11.7%
2025	11.2%

Charted by NFL Next Gen Stats through 2022 and by FTN Data from 2023, so part of any jump between 2022 and 2023 comes from the change of source.

Play Today's Plays

More defensive fronts

3-4 DefenseThe 3-4 uses three linemen, four linebackers and four defensive backs, with the outside linebackers often standing on the edges to rush.12.2%Nickel DefenseNickel puts five defensive backs on the field, usually with four linemen and two linebackers, and it is now the most common defense in football.65.8%Dime DefenseDime puts six defensive backs on the field, usually with four linemen and one linebacker, to defend obvious passing downs.10.3%Goal Line DefenseGoal Line packs eight or more defenders into the box with three or fewer defensive backs, for plays at the goal line or a yard or two to go.0.6%

Sources

Written for cover0. Usage numbers come from the play data credited on the About page.