Guitar Theory Cheat Sheet
Everything worth memorising on one page: intervals, scale and chord formulas, the chords of every key (interactive), the progressions behind most songs, the circle of fifths and a fretboard note map. Print it and stick it on the wall.
1 · The 12 notes
C · C♯/D♭ · D · D♯/E♭ · E · F · F♯/G♭ · G · G♯/A♭ · A · A♯/B♭ · B → then C again
One fret = one semitone. Two frets = a whole step. No sharp/flat between E–F and B–C. Fret 12 is the octave — the whole neck repeats from there.
2 · Intervals (the distances)
| semitones | interval | on the guitar / the sound |
|---|---|---|
| 0 | Unison / same note | same fret, same string |
| 1 | Minor 2nd | 1 fret up — the “Jaws” note |
| 2 | Major 2nd | 2 frets up (one whole step) |
| 3 | Minor 3rd | the sad third — minor chords |
| 4 | Major 3rd | the happy third — major chords |
| 5 | Perfect 4th | same fret, next string (except G→B) |
| 6 | Tritone | the tension note — blues ♭5, metal |
| 7 | Perfect 5th | the power-chord note |
| 8 | Minor 6th | dark, dramatic leap |
| 9 | Major 6th | sweet, country-flavoured leap |
| 10 | Minor 7th | dominant & m7 chords — bluesy |
| 11 | Major 7th | dreamy maj7 colour, leading tone |
| 12 | Octave | fret 12 = the open string, higher |
3 · Scale formulas
| scale | steps (W=2 frets, H=1) | degrees |
|---|---|---|
| Major (Ionian) | W W H W W W H | 1 2 3 4 5 6 7 |
| Natural minor (Aeolian) | W H W W H W W | 1 2 ♭3 4 5 ♭6 ♭7 |
| Major pentatonic | — | 1 2 3 5 6 |
| Minor pentatonic | — | 1 ♭3 4 5 ♭7 |
| Blues | — | 1 ♭3 4 ♭5 5 ♭7 |
| Dorian | W H W W W H W | 1 2 ♭3 4 5 6 ♭7 |
| Mixolydian | W W H W W H W | 1 2 3 4 5 6 ♭7 |
| Lydian | W W W H W W H | 1 2 3 ♯4 5 6 7 |
| Phrygian | H W W W H W W | 1 ♭2 ♭3 4 5 ♭6 ♭7 |
| Harmonic minor | W H W W H W+H H | 1 2 ♭3 4 5 ♭6 7 |
Every formula starts from the root you choose — see any of them on the full neck.
4 · Chord formulas
| chord | formula | example |
|---|---|---|
| Major | 1 3 5 | C = C E G |
| Minor (m) | 1 ♭3 5 | Am = A C E |
| Power chord (5) | 1 5 | C5 = C G — neither major nor minor |
| Diminished (°) | 1 ♭3 ♭5 | B° = B D F |
| Augmented (+) | 1 3 ♯5 | C+ = C E G♯ |
| Sus2 | 1 2 5 | Csus2 = C D G — 3rd swapped out |
| Sus4 | 1 4 5 | Csus4 = C F G — wants to resolve |
| Major 7 (maj7) | 1 3 5 7 | Cmaj7 = C E G B — dreamy |
| Dominant 7 (7) | 1 3 5 ♭7 | G7 = G B D F — pulls to C |
| Minor 7 (m7) | 1 ♭3 5 ♭7 | Am7 = A C E G — smooth minor |
| Add9 | 1 3 5 9 | Cadd9 = C E G D — pop shimmer |
5 · The chords of any key (interactive)
Harmonise the major scale and you get seven chords that always follow the same quality pattern. Pick a key:
| C major | I | ii | iii | IV | V | vi | vii° |
|---|---|---|---|---|---|---|---|
| chord | C | Dm | Em | F | G | Am | B° |
| function | tonic | subdom. | tonic | subdom. | dominant | tonic | dominant |
| A minor (relative) | Am i | B° ii° | C ♭III | Dm iv | Em v | F ♭VI | G ♭VII |
Same seven chords serve both keys — the relative minor just calls a different one home.
6 · Progressions that run the world
| numerals | in C | where you know it from |
|---|---|---|
| I–V–vi–IV | C G Am F | the four-chord pop loop |
| I–IV–V | C F G | folk, blues, rock & roll |
| ii–V–I | Dm7 G7 Cmaj7 | the jazz cadence |
| 12-bar blues | I I I I · IV IV I I · V IV I V | the blues form |
| vi–IV–I–V | Am F C G | the “sad” rotation of the pop loop |
| i–♭VII–♭VI–V | Am G F E | the Andalusian / flamenco descent |
| I–vi–IV–V | C Am F G | the 50s doo-wop loop |
7 · Circle of fifths
Clockwise adds a sharp, counter-clockwise adds a flat. A key's best-friend chords are its neighbours; relative majors and minors share a spoke. The interactive circle plays them.
8 · Natural notes on the neck
Learn E and A strings first — they name your barre chords. The octave shape (two strings over, two frets up) finds the same note anywhere else. Drill it in Note map mode.
This is one small slice of ThunderFret — the full interactive fretboard does chords, scales and ear training for free, and with Pro it even hears you play through the mic.
Enter the toolFrequently asked
What music theory should a guitarist learn first?
In order of payoff: the 12 notes and how frets are semitones; the major scale formula (everything else is measured against it); how chords are built from scale degrees (1-3-5); which chords live in a key (the diatonic table); and the handful of progressions that power most songs. That's exactly what this sheet covers.
How do I memorise the notes on the fretboard?
Learn the natural notes on the low E and A strings first (they name your barre chords), use the octave shape (two strings over, two frets up) to find the same note elsewhere, and remember fret 12 restarts the string. The map at the bottom of this sheet shows every natural note up to fret 12.
What is the circle of fifths actually for?
Three everyday jobs: reading key signatures (each step clockwise adds a sharp), finding a key's chords (a key's main chords are its neighbours on the circle), and smooth key changes (nearby keys share the most notes).
Can I print this cheat sheet?
Yes — use the print button (or Ctrl/Cmd+P) and print it or save it as a PDF. The page restyles itself for paper: dark theme off, tables and diagrams in print-friendly ink.