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AP Music Theory Cheat Sheet
One-page reference for the fundamentals and part-writing conventions covered in the AP Music Theory course. Test yourself with the music theory quiz.
Key signatures
Order of sharps: F♯ C♯ G♯ D♯ A♯ E♯ B♯. Order of flats: B♭ E♭ A♭ D♭ G♭ C♭ F♭.
Sharp keys: the major tonic is a half step above the last sharp. Flat keys: the major tonic is the second-to-last flat (one flat = F major). The relative minor is a minor 3rd below the major tonic and shares its key signature.
| Accidentals | Major | Minor | Accidentals | Major | Minor |
|---|---|---|---|---|---|
| 0 | C | a | |||
| 1♯ | G | e | 1♭ | F | d |
| 2♯ | D | b | 2♭ | B♭ | g |
| 3♯ | A | f♯ | 3♭ | E♭ | c |
| 4♯ | E | c♯ | 4♭ | A♭ | f |
| 5♯ | B | g♯ | 5♭ | D♭ | b♭ |
| 6♯ | F♯ | d♯ | 6♭ | G♭ | e♭ |
| 7♯ | C♯ | a♯ | 7♭ | C♭ | a♭ |
Scales, scale degrees and modes
| Scale | Whole/half-step pattern | Note |
|---|---|---|
| Major | W W H W W W H | Ionian |
| Natural minor | W H W W H W W | Aeolian; ♭3 ♭6 ♭7 vs. major |
| Harmonic minor | W H W W H A2 H | Raised 7 (leading tone) |
| Melodic minor (ascending) | W H W W W W H | Raised 6 and 7 ascending; natural minor descending |
| Dorian | W H W W W H W | Natural minor with ♮6 |
| Phrygian | H W W W H W W | Natural minor with ♭2 |
| Lydian | W W W H W W H | Major with ♯4 |
| Mixolydian | W W H W W H W | Major with ♭7 |
| Locrian | H W W H W W W | ♭2 and ♭5 |
Scale-degree names: 1 tonic · 2 supertonic · 3 mediant · 4 subdominant · 5 dominant · 6 submediant · 7 leading tone (half step below tonic) or subtonic (whole step below, as in natural minor).
Other collections: major pentatonic (1 2 3 5 6), minor pentatonic (1 ♭3 4 5 ♭7), whole-tone (all whole steps), chromatic (all half steps).
Meter
| Meter type | Beat divides into | Examples |
|---|---|---|
| Simple duple / triple / quadruple | 2 equal parts | 2/4, 3/4, 4/4 (also 2/2 = cut time) |
| Compound duple / triple / quadruple | 3 equal parts (dotted beat) | 6/8, 9/8, 12/8 |
In compound meter the top number ÷ 3 = beats per measure (6/8 has two dotted-quarter beats). Syncopation = accent on a weak beat or off the beat; hemiola = two groups of three heard as three groups of two (or vice versa).
Intervals
| Half steps | Interval | Inverts to |
|---|---|---|
| 0 | Perfect unison | Perfect octave |
| 1 | Minor 2nd | Major 7th |
| 2 | Major 2nd | Minor 7th |
| 3 | Minor 3rd | Major 6th |
| 4 | Major 3rd | Minor 6th |
| 5 | Perfect 4th | Perfect 5th |
| 6 | Augmented 4th / diminished 5th (tritone) | Diminished 5th / augmented 4th |
| 7 | Perfect 5th | Perfect 4th |
| 8 | Minor 6th | Major 3rd |
| 9 | Major 6th | Minor 3rd |
| 10 | Minor 7th | Major 2nd |
| 11 | Major 7th | Minor 2nd |
Inversion rule: numbers add to 9; major ↔ minor, augmented ↔ diminished, perfect stays perfect. Spelling matters: C–D♯ (augmented 2nd) and C–E♭ (minor 3rd) are both 3 half steps. Compound intervals: subtract 7 (a 10th = octave + 3rd).
Triads and seventh chords
| Quality | Intervals above root | Example |
|---|---|---|
| Major triad | M3 + P5 | C E G |
| Minor triad | m3 + P5 | C E♭ G |
| Diminished triad | m3 + d5 | C E♭ G♭ |
| Augmented triad | M3 + A5 | C E G♯ |
| Major seventh (MM7) | Major triad + M7 | C E G B |
| Dominant seventh (Mm7) | Major triad + m7 | C E G B♭ |
| Minor seventh (mm7) | Minor triad + m7 | C E♭ G B♭ |
| Half-diminished seventh (ø7) | Diminished triad + m7 | C E♭ G♭ B♭ |
| Fully diminished seventh (°7) | Diminished triad + d7 | C E♭ G♭ B♭♭ |
| Position | Bass | Triad figures | Seventh-chord figures |
|---|---|---|---|
| Root position | Root | (5/3) | 7 |
| First inversion | 3rd | 6 (6/3) | 6/5 |
| Second inversion | 5th | 6/4 | 4/3 |
| Third inversion | 7th | — | 4/2 (or 2) |
Diatonic chords and function
| Key | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| Major (triads) | I | ii | iii | IV | V | vi | vii° |
| Major (sevenths) | IM7 | ii7 | iii7 | IVM7 | V7 | vi7 | viiø7 |
| Minor, raised 7 (triads) | i | ii° | III | iv | V | VI | vii° |
| Minor (common sevenths) | — | iiø7 | — | iv7 | V7 | — | vii°7 |
Functions: tonic (I, vi, sometimes iii) → predominant (ii, IV, ii6, ii7) → dominant (V, V7, vii°) → tonic. Deceptive motion V → vi. The cadential 6/4 (a I6/4 sonority over scale degree 5, often labeled V6/4–5/3) decorates V; passing 6/4 and pedal (neighbor) 6/4 are the other common 6/4 types.
Cadences
| Cadence | Chords | Notes |
|---|---|---|
| Perfect authentic (PAC) | V(7) → I | Both root position; soprano ends on 1 |
| Imperfect authentic (IAC) | V(7) → I or vii° → I | Inversion present or soprano not on 1 |
| Half (HC) | … → V | Ends on V |
| Phrygian half | iv6 → V (minor) | Bass descends by half step 6–5 |
| Plagal | IV → I | “Amen” cadence |
| Deceptive | V → vi (VI in minor) | Avoids the expected tonic |
Phrase types: a period is two phrases where the first ends weaker (often HC) and the second ends stronger (PAC). Parallel period = phrases begin alike; contrasting period = they begin differently.
Four-part voice leading (common-practice conventions)
- Avoid parallel (consecutive) perfect 5ths and octaves between any two voices, including by contrary motion.
- Avoid direct (hidden) 5ths/octaves in the outer voices when the soprano leaps.
- Spacing: no more than an octave between soprano–alto and alto–tenor; tenor–bass may be wider.
- Avoid voice crossing and voice overlap.
- Don't double the leading tone; resolve it up to tonic when it is in an outer voice.
- Resolve chordal sevenths down by step.
- In root-position triads, usually double the root; in second-inversion (6/4) chords, double the bass.
- Avoid melodic augmented 2nds (watch ♭6–♯7 in harmonic minor) and other augmented leaps.
Non-chord tones
| Type | Approach | Leave |
|---|---|---|
| Passing tone | Step | Step, same direction |
| Neighbor tone | Step | Step back to the same note |
| Appoggiatura | Leap | Step (usually opposite direction) |
| Escape tone | Step | Leap (usually opposite direction) |
| Suspension (4–3, 7–6, 9–8; 2–3 in bass) | Same note (prepared) | Step down |
| Retardation | Same note (prepared) | Step up |
| Anticipation | Step or leap | Becomes a chord tone of the next chord (same note) |
| Pedal point | Held or repeated note | Usually bass, against changing harmonies |
Secondary chords and modulation
Secondary dominants tonicize a chord other than I: V/V in C is D–F♯–A; V7/IV in C is C–E–G–B♭. Secondary leading-tone chords: vii°/V or vii°7/V in C is F♯–A–C(–E♭).
Modulation to closely related keys (key signatures differ by at most one accidental — the relative key, dominant, subdominant and their relatives). Common-chord (pivot) modulation uses a chord diatonic in both keys, e.g. C major → G major via vi in C = ii in G (A minor).
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