Walk into any high school film room or an NFL coordinator’s office at 2:00 AM, and you’ll see it. Numbers scribbled on whiteboards. Lines zig-zagging across a green screen. It looks like high-level calculus, but it’s actually the passing tree for football, and honestly, it’s the only reason an offense doesn't collapse into total chaos the second the ball is snapped.
Most fans think a quarterback just tells a guy to "go deep." It doesn’t work like that. Not even close. If Justin Jefferson or Tyreek Hill just "ran around," they’d get leveled by a safety before the ball left the QB’s hand. The passing tree—or route tree—is the standardized numbering system that tells every receiver exactly where to go and how to get there. It’s the DNA of the passing game.
The Basic Math of the Passing Tree for Football
Here is the thing: the system is actually pretty simple once you realize it's just a map. In almost every playbook, from the Air Raid to the West Coast offense, even numbers are inside routes. Odd numbers are outside routes.
That’s the rule. Mostly.
If you hear a coach yell "9," he isn't asking for the price of a hot dog. He's telling the receiver to run a Go route. Straight down the sideline. No breaks. Just speed. On the flip side, an "8" is a Post route, where the receiver breaks toward the goalposts. See? Even numbers go toward the middle of the field. Odds go toward the sideline. It’s a language.
Breaking Down the Branches
Let's look at the "short" game first. The 0 or 1 is usually a Hitch or a Flat route. These are the "get the ball out fast because the blitz is coming" plays. You’re looking at maybe 3 to 5 yards. It’s gritty. It’s boring. It wins games.
Then you have the Slant (2). This is the bread and butter of the NFL. The receiver takes three steps up, plants his outside foot, and cuts hard toward the quarterback. It’s fast. If the timing is off by a tenth of a second, it’s an interception. If it’s on, it’s a first down.
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The 3 is the Out route. This is a nightmare for quarterbacks with weak arms. You have to throw the ball roughly 10 yards downfield and all the way to the sideline before the cornerback can jump it. If the ball floats? Pick-six. Every time.
Moving up the tree, we hit the 4 (In or Dig) and the 5 (Out). These are intermediate routes. We're talking 10 to 12 yards. These routes require "clearing out" the linebackers. You can't just run into a zone and hope for the best. You have to find the "window."
Then there's the 6 (Curl). The receiver sells the deep ball, then stops on a dime and turns back to the QB. It’s all about the "break." If you can't stop fast, you can't play receiver in this league.
The Big Gainers
The top of the passing tree for football is where the highlights happen.
- 7 (Corner/Flag): Breaking toward the back corner of the end zone.
- 8 (Post): Breaking toward the goalposts.
- 9 (Go/Fly/Streak): Just run. Fast.
Why the West Coast Offense Changed Everything
Bill Walsh. That’s the name you need to know. Before Walsh popularized the West Coast system with the San Francisco 49ers, passing was often seen as a desperation move. You ran the ball to "establish dominance," and you threw it when you had to.
Walsh flipped the script. He used the passing tree as an extension of the run game. Short, high-percentage throws. By using a numbered tree, he could call plays like "2-2-6," telling three different receivers exactly what to do with just three digits. It was efficient. It was deadly.
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Joe Montana wasn't the strongest guy. He didn't have a cannon. But he could hit a "2" (slant) or a "6" (curl) with surgical precision. This is where the nuance of the tree really shines. It’s not just about the route; it’s about the timing steps. A 3-step drop by the QB matches a short route. A 5-step drop matches an intermediate route. A 7-step drop? Better be a 7, 8, or 9.
The Evolution: "Choice" Routes and Post-Snap Reads
Modern football is getting weird. The old-school passing tree for football is still the foundation, but teams like the Kansas City Chiefs or the Miami Dolphins add "options" to it.
Imagine you're a receiver. You're told to run a 10-yard Out (a 5). But as you're running, you see the cornerback is playing way outside. If you run the 5, you're running right into him. In a "Choice" system, you have the permission to turn that 5 into a 4 (an In route) because the space is in the middle.
This is why chemistry between a QB and a receiver matters more than raw stats. If Patrick Mahomes thinks Travis Kelce is running an 8 (Post) but Kelce sees a safety sitting deep and turns it into a 6 (Curl), and the ball is already in the air? Disaster.
This "Option Tree" is basically the PhD level of football. It’s why rookies often struggle. They might know the tree, but they don't know how to "read the forest."
Common Misconceptions About the Tree
People think every team uses the exact same tree. They don't.
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While the "even-in, odd-out" logic is the gold standard, some coaches like to swap things. Some use colors. Some use tree names (Oak, Pine, Cedar) to represent different route combinations. But if you’re a kid trying to get recruited, stick to the standard 0-9 tree. That’s the universal language.
Another big mistake? Thinking the route ends when the line on the paper ends. Every coach will tell you: if the play breaks down and the QB starts scrambling, the tree is dead. You enter "scramble drill" mode. This is where the best receivers find open grass, regardless of what "number" they were assigned.
How to Actually Use This Knowledge
If you’re a coach or a player, don’t just memorize the numbers. Understand the "why."
A "9" route isn't just to catch a touchdown; sometimes it’s to "clear out" the safety so the "2" (slant) underneath is wide open. This is called vertical stretch. You’re stretching the defense until they snap.
If you’re a quarterback, your feet are the clock.
- 1-step drop: Think 0 or 1.
- 3-step drop: Think 2 or 3.
- 5-step drop: Think 4, 5, or 6.
- 7-step drop: Think 7, 8, or 9.
If your feet don't match the route, you’re either going to be too early—throwing the ball before the receiver has turned—or too late, which usually ends with you getting sacked.
Actionable Steps for Mastering the Passing Tree
- Film Study: Watch an NFL game this Sunday. Pick one receiver. Don't watch the ball. Watch his feet. Count his steps. See if you can identify if he ran a 3, a 5, or a 9.
- The Paper Test: Draw a line representing the line of scrimmage. Draw the nine basic routes from memory. If you can’t do it in 30 seconds, you don't know it well enough yet.
- Coordinate the Footwork: If you're a player, practice your breaks. A "4" (In) requires a different plant than a "2" (Slant). The angle is steeper. The speed is different.
- Learn the "Counters": For every route on the tree, there is a "double move." A Slant-and-Go (Sluggo) or a Post-Corner. These aren't on the basic tree, but they are the "branches" that grow off it once you've mastered the basics.
The passing tree for football isn't just a diagram in a dusty playbook. It’s a living, breathing system that evolves every season. But at its core, it remains the same simple, numbered logic that has governed the game for decades. Master the numbers, and you master the field.