The 12 Notes
Western music — everything from classical to metal — uses 12 distinct pitches. Move up through all 12 in half-step increments and you arrive back at the same note one octave higher. This is called the chromatic scale.
The 7 natural notes you already know: C D E F G A B. Between most of them sits a half step — an additional pitch that gets a sharp (♯) or flat (♭) name depending on context. That gives you 12 total:
C — C♯/D♭ — D — D♯/E♭ — E — F — F♯/G♭ — G — G♯/A♭ — A — A♯/B♭ — B — (back to C)
Notice there is no sharp between E and F, and no sharp between B and C. Those pairs are already a half step apart — the closest distance possible in Western music.
Sharps and Flats — Same Note, Different Name
C♯ and D♭ are the same pitch on the piano and the same fret on the guitar. The choice of name depends on context: which key you're in, which direction the harmony is moving. This is called enharmonic equivalence.
On the fretboard, every fret is one half step. Move up two frets and you've moved a whole step (also called a whole tone). That's it — the entire system of Western pitch is built on those two distances: the half step and the whole step.
What Is an Interval?
An interval is the distance between two notes. That's all. When you play two notes — either in sequence or at the same time — the distance between them has a name. Those named distances are intervals.
Every scale is a specific sequence of intervals from a root note. Every chord is a specific stack of intervals. Change one interval and you get a different scale or a different chord. That's the entire measuring system.
All the Named Intervals
Starting from any note and counting up:
| Semitones | Interval name | Example (from C) |
|---|---|---|
| 0 | Unison (same note) | C → C |
| 1 | Minor 2nd (half step) | C → C♯ |
| 2 | Major 2nd (whole step) | C → D |
| 3 | Minor 3rd | C → E♭ |
| 4 | Major 3rd | C → E |
| 5 | Perfect 4th | C → F |
| 6 | Tritone (augmented 4th / diminished 5th) | C → F♯ |
| 7 | Perfect 5th | C → G |
| 8 | Minor 6th | C → A♭ |
| 9 | Major 6th | C → A |
| 10 | Minor 7th | C → B♭ |
| 11 | Major 7th | C → B |
| 12 | Octave | C → C (higher) |
The tritone sits exactly halfway between two octaves — 6 semitones from the root. It's the most dissonant interval in Western music, the source of tension in dominant 7th chords, and the interval that drives nearly every harmonic resolution.
Perfect vs. Imperfect Intervals
You'll notice that 4ths, 5ths, unisons, and octaves are called "perfect" while 2nds, 3rds, 6ths, and 7ths come in major and minor versions. Why?
Perfect intervals don't have a major or minor form — they're the same in both major and minor scales, which makes them stable regardless of context. They were historically considered the most consonant, "pure" intervals. Imperfect intervals (2nds, 3rds, 6ths, 7ths) exist in two sizes — their major or minor quality shifts depending on the scale and key.
On the guitar, the tuning between most strings is a perfect 4th (5 frets). The exception is the G to B string, which is a major 3rd (4 frets). That's why chord shapes shift slightly across that string pair.
Exercise 1
Name Every Note on the Low E String
Start from the open low E string and play every fret up to the 12th. Name each note out loud as you play it: E — F — F♯ — G — G♯ — A — A♯ — B — C — C♯ — D — D♯ — E. The 12th fret is an octave above the open string. Do this until you can name any fret on that string without thinking.
Load chromatic scale on fretboard →Exercise 2
Find Perfect 5ths Across Two Strings
Pick any note on string 5 (A string). Now find the same note's perfect 5th — 7 semitones higher. You can move up 7 frets on the same string, or you can find it 2 frets higher on string 4 (D string). Both are the same note. Practice moving between those two positions for any root — this is the foundation of power chords and one of the most useful geometric patterns on the fretboard.
Why Intervals Are the DNA of Everything
Every scale is a set of intervals from a root. The major scale is: whole, whole, half, whole, whole, whole, half — or in semitones: 0-2-4-5-7-9-11. The minor scale is: 0-2-3-5-7-8-10. Change one of those numbers and you get a different scale with a different character.
Every chord works the same way. A major triad is always 0-4-7 (root, major 3rd, perfect 5th). A minor triad is 0-3-7. A single semitone shift — from 4 to 3 — changes the emotional quality completely.
Once you know your intervals cold, every scale, chord, and mode becomes just a recipe of distances from a root note. That's the entire system.
Challenge
30-Second Interval Drill
Have a friend (or just yourself) call out any two frets on the same string — for example, "fret 3 and fret 8." Your job: name the interval between them in under 30 seconds. Count the semitones, then identify the name. Work through at least 10 random pairs. When you can get every one right in under 10 seconds each, you actually know your intervals.
From here, every other concept in this guide builds directly on intervals. The next page covers scales and keys — which are just specific patterns of intervals stacked from a chosen root note.