Intervals in Music
Understand the distance between any two notes — the foundation of melody, harmony, and chord construction.
What Is an Interval?
An interval is the distance in pitch between two notes. Every melody you sing and every chord you play is built from intervals.
Key Point: Intervals are named by two properties — number (how many letter names apart) and quality (the exact number of half steps).
Example — C to E (a Third)
Melodic & Harmonic Intervals
Intervals can be played one note after another (melodic) or both notes at the same time (harmonic).
Melodic vs Harmonic — C to G (a Fifth)
Interval Numbers
The interval number tells you how many letter names are spanned, counting both the lower and upper note.
Intervals from C — Unison through Octave
Interval Quality
The number alone isn't enough — quality tells you the exact size in half steps. There are five qualities.
The Five Interval Qualities
| Quality | Abbreviation | Applies To | Description |
|---|---|---|---|
| Perfect | P | Unison, 4th, 5th, 8ve | The "pure" consonant intervals found in major and minor scales |
| Major | M | 2nd, 3rd, 6th, 7th | The larger version — found between the root and that degree in a major scale |
| Minor | m | 2nd, 3rd, 6th, 7th | One half step smaller than major |
| Augmented | A or + | Any interval | One half step larger than perfect or major |
| Diminished | d or ° | Any interval | One half step smaller than perfect or minor |
Remember: Unison, 4ths, 5ths, and octaves are called perfect intervals. They don't have major or minor forms. 2nds, 3rds, 6ths, and 7ths come in major and minor versions.
Intervals by Half Steps
A complete reference table showing every interval from unison to octave with the exact number of half steps (semitones).
Complete Interval Reference
| Half Steps | Interval Name | Example from C | Sound Character |
|---|---|---|---|
| 0 | Perfect Unison (P1) | C → C | Same note |
| 1 | Minor 2nd (m2) | C → D♭ | Tense, dissonant |
| 2 | Major 2nd (M2) | C → D | Bright step |
| 3 | Minor 3rd (m3) | C → E♭ | Sad, dark |
| 4 | Major 3rd (M3) | C → E | Happy, bright |
| 5 | Perfect 4th (P4) | C → F | Open, strong |
| 6 | Tritone (A4/d5) | C → F♯/G♭ | Unstable, restless |
| 7 | Perfect 5th (P5) | C → G | Open, powerful |
| 8 | Minor 6th (m6) | C → A♭ | Bittersweet |
| 9 | Major 6th (M6) | C → A | Warm, sweet |
| 10 | Minor 7th (m7) | C → B♭ | Bluesy, expectant |
| 11 | Major 7th (M7) | C → B | Dreamy, tense |
| 12 | Perfect Octave (P8) | C → C | Complete, same pitch class |
Common Intervals on the Staff
Visual reference for how key intervals look on the treble clef staff. All examples start from C4.
Minor 3rd — C to E♭ (3 half steps)
Perfect 4th — C to F (5 half steps)
Perfect 5th — C to G (7 half steps)
Perfect Octave — C4 to C5 (12 half steps)
Intervals in Different Major Keys
Intervals are not tied to C major — they work identically in every key. The distance in half steps stays the same; only the letter names change. Here are the intervals built from the root of several major keys.
Why this matters: A Major 3rd is always 4 half steps, whether it's C→E, G→B, D→F♯, or F→A. Understanding intervals in multiple keys trains your ear and your reading ability beyond just the "white keys."
G Major — All Intervals from G (1♯)
D Major — All Intervals from D (2♯)
F Major — All Intervals from F (1♭)
A Major — All Intervals from A (3♯)
All Intervals — Quick Comparison Across Keys
| Key | m2 | M2 | m3 | M3 | P4 | P5 | m6 | M6 | m7 | M7 | P8 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| C Major | C→D♭ | C→D | C→E♭ | C→E | C→F | C→G | C→A♭ | C→A | C→B♭ | C→B | C→C |
| G Major | G→A♭ | G→A | G→B♭ | G→B | G→C | G→D | G→E♭ | G→E | G→F♮ | G→F♯ | G→G |
| D Major | D→E♭ | D→E | D→F♮ | D→F♯ | D→G | D→A | D→B♭ | D→B | D→C♮ | D→C♯ | D→D |
| F Major | F→G♭ | F→G | F→A♭ | F→A | F→B♭ | F→C | F→D♭ | F→D | F→E♭ | F→E | F→F |
| A Major | A→B♭ | A→B | A→C♮ | A→C♯ | A→D | A→E | A→F♮ | A→F♯ | A→G♮ | A→G♯ | A→A |
The Pattern: No matter what key you're in, a Major 3rd is always 4 half steps and a minor 3rd is always 3 half steps. A Perfect 5th is always 7 half steps. The letter names and accidentals change, but the distance in half steps stays the same. Notice how sharp keys use ♮ (natural) to lower sharped notes, while flat keys add ♭ (flat) to natural notes — both achieve the same result: reducing the interval by one half step.
Consonance & Dissonance
Intervals are traditionally grouped by how "stable" or "tense" they sound when played harmonically.
Consonance vs Dissonance Spectrum
| Category | Intervals | Character |
|---|---|---|
| Perfect Consonance | P1, P5, P8 | Stable, open, resolved |
| Imperfect Consonance | m3, M3, m6, M6 | Pleasant, warm, sweet |
| Mild Dissonance | M2, m7 | Slightly tense but functional |
| Sharp Dissonance | m2, M7 | Very tense, wants to resolve |
| Ambiguous | P4, Tritone | Context-dependent — can sound either way |
Tip: The perfect 4th is unique — it's consonant in melody and most contexts, but considered dissonant when it's the lowest interval in a chord. The tritone (augmented 4th / diminished 5th) was historically called "diabolus in musica" (the devil in music) because of its extreme instability.
Song Mnemonics for Ear Training
A popular way to learn intervals by ear is to associate each one with the opening of a well-known song.
Minor 2nd ↑
Think of the suspenseful two-note motif from the movie "Jaws."
Major 2nd ↑
The first two notes of "Happy Birthday" — a bright whole step up.
Minor 3rd ↑
The opening of "Greensleeves" — a gentle, melancholic rise.
Major 3rd ↑
The start of "When the Saints Go Marching In" — bright and cheerful.
Perfect 4th ↑
"Here Comes the Bride" (Bridal Chorus) — a strong, open leap.
Tritone ↑
"The Simpsons" theme opens with this distinctive, quirky interval.
Perfect 5th ↑
The opening of "Twinkle Twinkle Little Star" — open and powerful.
Minor 6th ↑
"The Entertainer" (Scott Joplin) — a bittersweet, wide leap.
Major 6th ↑
"My Bonnie Lies Over the Ocean" — a warm, sweeping rise.
Minor 7th ↑
The first two notes of the "Star Trek" original theme — bold and expectant.
Major 7th ↑
"Take On Me" (A-ha) — the dreamy, wide leap in the chorus.
Octave ↑
"Somewhere Over the Rainbow" — the iconic, soaring opening leap.
Tips for Identifying Intervals
Quick strategies to build speed and accuracy when recognizing intervals.
Count Letter Names
Always count inclusively. C to G: C(1) D(2) E(3) F(4) G(5) = a 5th. This gives you the interval number.
Use the Major Scale
All intervals from the root of a major scale are either major or perfect. Anything smaller is minor or diminished.
Count Half Steps
When in doubt, count semitones on a keyboard. This gives you the exact quality: M3 = 4, P5 = 7, etc.
Inversion Shortcut
An interval and its inversion always add up to 9. A 3rd inverts to a 6th, a 2nd to a 7th. Major inverts to minor, perfect stays perfect.
Inversion Rule: To invert an interval, subtract the number from 9. Quality flips: Major ↔ Minor, Augmented ↔ Diminished, Perfect stays Perfect. Example: M3 inverts to m6, P4 inverts to P5.