Defensive Line Techniques: From the 0-Technique to the 9

By 4Football Staff · October 17, 2026 · 10 min read

A 3-technique is not a number on a jersey. Learn the numbering system defensive linemen use to line up over blockers, and what each alignment asks the player to do.

Listen to a coach describe a defensive front and you will hear numbers that have nothing to do with jersey numbers or the size of the team. "Our nose plays a zero. The Sam is a nine. We want the tackle in a three, and the end in a five." To someone new to the sport this sounds like code, and in a sense it is. It is a shorthand that lets a coach describe exactly where every lineman stands in relation to the offensive line, in a few syllables, to a group of teenagers or professionals who all know what it means.

These numbers are called techniques, and they are one of the most useful ideas in defensive football. A technique number does two things at once: it tells the player where to line up, and it signals which part of the field he is responsible for. Once you learn the system, defensive fronts like the 4-3 and the 3-4 become far easier to read.

This article walks through the numbering from 0 to 9, explains how the numbers are built, describes what each alignment typically asks of a player, and lays out the main techniques linemen use after the snap. Details differ from program to program, and a few numbers have competing meanings, so where that happens it is noted.

How the numbers are built

The system is based on the offensive linemen who are directly in front of the defender. Each blocker has a number, and the defender's alignment is described by his position relative to that blocker.

The rules are simple:

1. Even numbers mean head-up. A defender lined up directly across from a blocker, nose to nose, gets the even number assigned to that blocker.
2. Odd numbers mean a shade. A defender lined up on one shoulder of a blocker gets an odd number. The 3, for example, sits between the guard (2) and the tackle (4), on the guard's outside shoulder.
3. The letter "i" means inside shoulder. When a coach wants to say a defender lines up on the inside shoulder of a blocker, he adds an "i" to the number, as in 2i or 4i.

Across the middle of the line, the numbers run like this. The center is zero. The guards are two. The tackles are four. The tight end is six. A defender over the center is a 0-technique, one on the guard is a 2, one on the tackle is a 4, and one on the tight end is a 6. The odd numbers in between mark the shoulders.

All of that assumes a standard offensive formation with a tight end on one side. Without a tight end, the offensive tackle is the last blocker on the line, and the outside shade of the tackle is a 5, as it would be with one. The numbers describe the alignment of the defender, not the position of the blocker, so they stay the same when the offense changes personnel.

The numbers one at a time

0-technique

The defender lines up directly over the center, nose to nose. This is the classic nose tackle alignment in a 3-4 defense (see the 3-4 defense explained). A 0-technique is usually a thick, strong player, since the job requires him to take on the center, and often a guard, at the same time. Because he is head-up, he does not have a single gap; he can be asked to control the A gaps on both sides by occupying blockers.

1-technique

The defender lines up on a shoulder of the center, shaded to one side, usually the side where the offense is expected to run or where the defense needs more strength. Most 1-techniques are tackles in 4-3 fronts. The 1-technique is responsible for the A gap on his shaded side in a one-gap system.

2-technique and 2i

A 2-technique is head-up on the offensive guard. A 2i is on the guard's inside shoulder. The 2i alignment points the defender at the A gap, so it is common for run-stopping tackles who need to plug the middle.

3-technique

A 3-technique lines up on the outside shoulder of the guard. He is facing the B gap, the space between the guard and the tackle. The 3-technique is one of the most celebrated alignments in the 4-3 defense, because it combines a strong run position with a straight line to the quarterback. A good 3-technique can disrupt both the run and pass game, which is why teams look for athletic defensive tackles to play it.

4-technique and 4i

A 4-technique is head-up on the offensive tackle. A 4i is on his inside shoulder, aiming at the B gap. The 4-technique is mainly seen in 3-4 fronts, where the defensive ends line up over the tackles rather than outside them, and it asks the player to take on blockers and hold the point of attack.

5-technique

A 5-technique lines up on the outside shoulder of the offensive tackle. He is facing the C gap, between the tackle and the tight end. In a 3-4 defense, the defensive ends often play the 5-technique. In a 4-3, an end might play a 5 against a team that runs the ball inside. The 5-technique can rush the passer from a strong position, because his path to the quarterback is shorter than it would be from further outside.

6-technique

A 6-technique is head-up on the tight end. It is a heavy-contact alignment and demands a defender who can take on a tight end in the run game and still contain the edge. Some teams use a linebacker or a strong-side end at 6.

7-technique

A 7-technique lines up on the inside shoulder of the tight end. It is a tight alignment that cuts down on the tight end's room to block inward, and it is common for a strong-side end in certain fronts.

8-technique

The 8-technique is the least standardized of the numbers. In some playbooks it is not used at all. When it appears, it is typically a head-up alignment on a second tight end, a wing or an H-back who lines up outside the first tight end, so treat the meaning as team-specific. If you hear it, ask which program's terms are being used.

9-technique

A 9-technique lines up outside the widest blocker on the line, usually outside the tight end. This is the wide alignment of the edge rusher. A defender at 9 has a long route to the quarterback, but also a wide-open path for a speed rush. He is responsible for the D gap, the outermost gap, in one-gap systems, and for containing runs that try to go around the end.

A quick reference table

Treat the table as a guide. A coach in one program may use "6" to mean something a coach in another would call a "7" and teams add their own labels, especially for in-between alignments.

Fronts built from these numbers

Once you know the numbers, a front can be described in a few words.

• A common 4-3 "under" front places a 1-technique and a 3-technique inside, with ends on the outside. The idea is that the 3-technique lines up to the side away from the tight end, where he can attack the B gap while a linebacker sits behind him.
• A traditional 3-4 uses a 0-technique nose and two 5-techniques, which is why it is often shown with "0, 5, 5" as the line. The linebackers behind them handle the other gaps. For the full picture see the article on the 4-3 defense and the 3-4 article linked above.
• A "bear" style front covers several offensive linemen with defenders at once, a subject for its own article.

These descriptions are useful for understanding what you are looking at. They are not rigid, because a coach may adjust a lineman's technique mid-game to take advantage of a matchup or react to a formation.

One gap or two

The technique number says where to stand. A separate question is what to do after the snap. Two basic philosophies answer it.

One-gap

In a one-gap system, each defender is assigned a single gap and attacks it. The aggressive tackle penetrates upfield, trying to arrive in the backfield before the runner reaches the line. The system is quick and disruptive, and it trades some reliability against double-teams for speed. Most 4-3 defenses use one-gap principles on the line.

Two-gap

In a two-gap system, a defender is responsible for the gaps on both sides of the blocker he is lined up against. He engages the blocker, controls him with his hands, reads where the ball is going, and sheds the blocker to make the play in the correct gap. A 0-technique nose tackle in a 3-4 is a classic example. The approach demands strong, patient players who can hold the line, and it frees linebackers to run and make tackles. Two-gapping linemen often do not record many sacks, but their job is to occupy blockers.

Which system a team uses depends on its personnel. A defense with a few big, powerful linemen may use two-gap; one with quick, athletic linemen may use one-gap. The topic is closely tied to run fits and gap responsibility, which describes how the linebackers and safeties complete the picture.

What linemen do after the snap

Whatever the alignment, linemen use a set of core techniques.

1. A fast first step. The defender who gets off the ball quicker than the blocker wins leverage. Most coaches emphasize snap count recognition and a short, explosive first move.
2. Pad level. The lower pad usually wins. A defender who stays low can drive upward through the blocker's chest.
3. Hand placement. Hands inside the blocker's frame, on his chest or shoulder pads, gives control. A defender who gets his hands on the blocker first and holds the blocker away from his body can shed him on his own terms.
4. Reading the blocker. Linemen watch the offensive linemen's movements. A guard who drops back is setting up pass protection. One who fires forward is run blocking. Coaches teach linemen to read the "key" and react.
5. Shedding. Once the lineman knows where the ball is, he throws off the blocker, using his hands and a push-pull motion, and moves to the ball.
6. Rushing the passer. On pass plays, the lineman picks a pass rush move (see pass rush moves) and a path. The rush lanes are the paths to the quarterback that the defense wants to keep. Rushers who lose their lanes let the quarterback step up.

Special techniques

Beyond alignment, some fronts use specific named techniques.

• Slants and angles. Linemen move diagonally across the line at the snap, rather than straight ahead, to change the angle of attack.
• Stunts and twists. Two linemen swap paths so the blockers pick up the wrong rusher.
• Contain. An end stays outside the quarterback, preventing a scramble to the outside.
• Spill and squeeze. On a run play, a lineman can "spill" the ball carrier by forcing him wide or "squeeze" the gap to keep him inside. This is where defensive line technique meets the work of linebackers and safeties.

Common mistakes

Beginners often misread the system. A few corrections:

• Technique numbers are not gap numbers. A 3-technique faces the B gap, but "3" is not the same as "B." The technique is the alignment; the gap is the target.
• A technique is not a position. A 4-3 defensive tackle might line up in a 1, 2i or 3 on different plays, and an end might line up in a 5, 7 or 9. The label depends on the play, not the player.
• The numbers move with the offense. A tight end on the other side changes which defender is a 7 or a 9.
• Coaches vary. Some programs use letters or names ("Eagle," "Tite," "Shade") for the same alignments.

Where to see it

On the next game, watch the pre-snap alignment of the defensive line. Locate the center, then count outward. Is the defensive lineman across from the center, or shaded? Is the end across from the tackle, or outside the tight end? You can match what you see with a team's profile on the teams page, track a game on the scores page, and learn the basics for yourself in the Play section. Coaches at different levels choose different words, so ask your own staff what their numbers mean.

What to remember

• Technique numbers describe where a defensive lineman lines up in relation to the offensive linemen: even numbers are head-up, odd numbers are shades.
• The center is 0, the guards 2, the tackles 4 and the tight end 6; the odd numbers mark the shoulders, and an "i" marks the inside shoulder.
• A 3-technique faces the B gap, a 5-technique the C gap, and a 9-technique is the wide edge rusher.
• Some numbers, such as the 8, are not standardized and vary by program.
• After the snap, linemen play one gap or two, depending on the scheme and the personnel.
• Fast first steps, low pads and good hands are the common skills that make any technique work.