Learn To Think In Intervals With The Same/Adjacent/Octave Rule

If I showed you these two notes, would you know what the interval is between them?

What about these two?

If yes, great. Carry on with what you were doing.

But if no?

Then let me show you:

1. how to figure these intervals out quickly, and
2. why you would even care about doing so.

The Missing Puzzle Piece

There are three ways to describe a guitar part: where, what, & how.

Where

The first way is built around the idea of showing you where the notes are. TAB and most YouTube videos are like this. They’re saying “put your finger here.”

What

The second way is built around the idea of showing you what the notes are called. Standard notation works this way. It’s saying “play the note called _____.”

How

The third way is built on the idea of telling you how the notes function. I associate this style with David Hamburger and Tomo Fujita, who describe licks by saying things like “minor third to major third, fifth, sixth, root.”

They’re telling you what each note is in relation to the chord you’re playing over at that moment. It’s how pros do it.

Learning to think this way is wildly powerful:

• it opens up vastly more soloing options than learning scales & modes ever will
• it teaches you to navigate the fretboard contextually (so it actually sticks in your brain)
• it makes it easy build any chord you might need (C#7b9? No problem!)
• when you find some new chord voicing, you can give it a name (ah, this is an F#m11)
• and best of all, it leverages guitar’s great strength (fretboard shapes) without trapping you into a box or pattern.

That said, it’s not always easy to get up to speed with this.

As guitarists, we’re used to seeing “chords” and “soloing” as two different things. But the reality is that they’re two sides of the same coin.

It can be hard to make sense of what intervals are in a chord. But it doesn’t have to be. We can figure out what we don’t know by using what we do know. It’s like sudoku.

To Shape Or Not To Shape

Navigating the fretboard strictly with shapes is detrimental to your understanding of the guitar.

It’s how we get trapped in scale shapes, playing the same stale licks over and over again. It’s how we all got so damned confused about modes.

But that’s not to say that shapes don’t have their place.

The physical distances between two notes on your fretboard is irreducible—the sound and the “geography” are inseparable.

For example:

• one fret up on the same string will always be a half step
• two frets up on the same string will always be a whole step

There are many irreducible intervals like this. To a pro player, they’re all pretty obvious. For those of us still aspiring to professional-grade guitar skills, learning these intervals is huge leap forward in our understanding.

In GuitarOS: Practical Theory, we drill them with intelligent flash cards. But even still, some of the wider ones are tricky to conceptualize.

The Same/Adjacent/Octave Rule

• Same: learn the intervals between two notes on the same string by brute force.
• Adjacent: learn the intervals between two notes on adjacent strings by relating them to the major scale.
• Octave: for intervals that span two strings, it’s faster to count backward from the octave.
• Octave, part two: for intervals spanning more than two strings, use octave shapes to “collapse” the interval onto a same or adjacent string.

Let’s break this down.

Same:

• If you move up one fret, that’s a half step. It doesn’t matter where you are. Any note, any string, anywhere on the guitar. One fret up = a half step. (We’ll double back to cover one fret/half step down in just a bit.)
• 
• If you move up two frets, that’s a whole step. Again: doesn’t matter where you are on the guitar, this is true 100% of the time.
• 
• If you move up three frets, that’s a minor third. And that’s true anywhere on the guitar.
• 
• If you move up four frets, that’s a major third. Again: true everywhere on the guitar.
• 
• We could continue on this way indefinitely, but very quickly we find that these intervals are easier to reach by moving over a string.

Adjacent:

• To use the adjacent method, we need to know the basic major scale shape.
• Here is how we make a major scale starting on the 6th string:
• 
• The root is here, and we call it 1.
• 
• Each step up the major scale is a new number.
• 
• This shape is the same starting on the 6th string as it is on the 5th string:
• 
• the intervals are the same:
• 

Major Third

Ok, with that little sidebar out of the way, we can say that this shape is a major third:

And that’s true everywhere except between the 3rd & 2nd strings:

This shape is a fourth.

And that’s true everywhere except between the 3rd & 2nd strings:

This shape is a fifth:

And that’s true everywhere except between the 3rd & 2nd strings

Commit these three to memory, and use them anytime you’re trying to visualize intervals on adjacent strings.

(Except between the 3rd & 2nd strings of course!)

Octave

There are a bunch of octave shapes on the guitar, but let’s just focus on this one for now:

You can see it embedded in the same major scale shape we looked at a minute ago:

Notice that after 7 comes 1. We could call this note “8.” (Eight is where the “oct” in “octave” comes from, same place as octopus and octagon.)

But really this note is the root again, which we call 1.

Another way of thinking about this is that the note a fret below the root is the 7 or “major seventh”.

And the note three frets below the 1 is the 6 or “sixth.”

It’s faster to count backward from the octave than it is to count up from the root.

So when you see this interval and wonder what it is:

…you could count up…

…but it’s faster to count backward from the octave:

Other Octaves

Counting backward from the octave is great, but what about notes that are separated by more than two strings?

Here we can use our octave shapes to “sudoku” our way from something foreign to something familiar.

First let’s review the common octave shapes:

If we see this chord

and want to know what this interval within it is

we can use the octave shape to collapse this note

down an octave to this note

And know that that’s our familiar major third.

In the same chord,

…we might wonder what’s the interval between these two notes

so we use octave shapes to collapse this note

down an octave to here

and from there can use our count backward from the octave trick to know that this is a 6th.

Isn’t this a lot of work?

Like common core math for guitar playing?

Sure, the first few times you do it.

But once you’ve done it a few times, you wind up knowing more and more intervals on sight.

From each of these new guideposts, you can lean further and further out into the things you don’t know.

Other Notes

You may have noticed that we didn’t cover all the possibilities—there are notes that aren’t in the major scale that get used all the time.

These are easy to figure out too.

We use the major scale as our measuring stick.

That means we name these in-between notes based on how they relate to the major scale.

The note below the 7? It’s the “flat seven” or “minor seven.”

The note below the 5? It’s the “flat five.”

The note above the 5? It’s the “sharp five.”

There’s more to naming chords than we’ve covered here, but let’s leave it there for now.

What about that pesky 3rd & 2nd string?

You can absolutely learn how the the major scale plays over the “wrinkle” of the 3rd & 2nd strings.

But instead of learning them all this way, I find it’s better to extrapolate & reverse engineer.

Again: take what you know, incorporate any clues from the context, and use that to figure out what you don’t know.

Recap:

• memorize same string intervals like half step, whole step, minor third, and major third.
• use the basic major scale shape to ID adjacent string intervals like major third, fourth, and fifth.
• rather than count up through the whole major scale, it’s faster to count backward from the octave when IDing intervals like the sixth and the major seventh.
• for intervals separated by more than an octave, use the standard octave shapes to collapse notes downward into more familiar territory.
• we can also ID the in-between notes. we use the major scale as our measuring stick: sharp five, flat seven, etc.
• this may seem labor intensive, but a little bit of work now saves you a ton of blind wandering later.
• like sudoku, we’re using what we know to figure out what we don’t know.