Every scale, every chord, every melody — it all comes down to intervals. An interval is simply the distance between two notes. Once you understand intervals, everything else in music theory becomes logical instead of arbitrary.
This guide covers all 13 intervals from unison to octave, with song references to help you hear each one and diagrams to see them on piano and fretboard.
What Is an Interval?
An interval measures the distance between two pitches. That's it. Play a C and then play an E — the distance between them is a "major third." Play a C and a G — that's a "perfect fifth."
Intervals are the atoms of music. Scales are patterns of intervals. Chords are stacks of intervals. Melodies are sequences of intervals. Understanding intervals means understanding the building blocks that everything else is made from.
Every interval has two properties:
- Size — how many semitones (half steps) apart the notes are. C to E is 4 semitones.
- Quality — the character name: perfect, major, minor, augmented, or diminished. C to E is a "major" third. C to Eb is a "minor" third.
Counting in Semitones
A semitone (half step) is the smallest distance between two notes in Western music. On a piano, it's the distance from one key to the very next key (including black keys). On a guitar, it's one fret.
The chromatic scale lists all 12 notes, each one semitone apart:
C → C#/Db → D → D#/Eb → E → F → F#/Gb → G → G#/Ab → A → A#/Bb → B → C
To find any interval, count the semitones between the two notes. C to F? C(0) → C#(1) → D(2) → Eb(3) → E(4) → F(5). That's 5 semitones = a perfect fourth.
All 13 Intervals
Here are all intervals within one octave, from smallest to largest:
| Semitones | Interval Name | Example (from C) | Sound |
|---|---|---|---|
| 0 | Unison | C → C | Same note |
| 1 | Minor 2nd | C → Db | Tense, close |
| 2 | Major 2nd | C → D | Bright, stepping |
| 3 | Minor 3rd | C → Eb | Sad, dark |
| 4 | Major 3rd | C → E | Happy, bright |
| 5 | Perfect 4th | C → F | Open, hymn-like |
| 6 | Tritone (Aug 4th / Dim 5th) | C → F# | Unstable, eerie |
| 7 | Perfect 5th | C → G | Strong, powerful |
| 8 | Minor 6th | C → Ab | Bittersweet |
| 9 | Major 6th | C → A | Warm, sweet |
| 10 | Minor 7th | C → Bb | Bluesy, unresolved |
| 11 | Major 7th | C → B | Dreamy, jazzy |
| 12 | Octave | C → C | Same note, higher |
Song References for Ear Training
The fastest way to learn intervals by ear is to associate each one with a familiar song. Here are widely used references:
- Minor 2nd (1) — "Jaws" theme (ascending), "Fur Elise" (descending)
- Major 2nd (2) — "Happy Birthday" (first two notes), "Frere Jacques"
- Minor 3rd (3) — "Greensleeves" (ascending), "Hey Jude" (descending)
- Major 3rd (4) — "Oh When the Saints" (ascending), "Summertime" (descending)
- Perfect 4th (5) — "Here Comes the Bride", "Amazing Grace"
- Tritone (6) — "The Simpsons" theme, "Maria" (West Side Story)
- Perfect 5th (7) — "Star Wars" main theme, "Twinkle Twinkle"
- Minor 6th (8) — "The Entertainer" (ascending)
- Major 6th (9) — "My Bonnie Lies Over the Ocean"
- Minor 7th (10) — "Somewhere" (West Side Story), "Star Trek" theme
- Major 7th (11) — "Take On Me" (a-ha, chorus first two notes)
- Octave (12) — "Somewhere Over the Rainbow"
Intervals in Scales
Scales are defined by their interval patterns. The major scale follows: W–W–H–W–W–W–H (whole step = 2 semitones, half step = 1 semitone).
This means the intervals from the root are always the same, regardless of key:
- Root → 2nd: Major 2nd (2 semitones)
- Root → 3rd: Major 3rd (4 semitones)
- Root → 4th: Perfect 4th (5 semitones)
- Root → 5th: Perfect 5th (7 semitones)
- Root → 6th: Major 6th (9 semitones)
- Root → 7th: Major 7th (11 semitones)
- Root → Octave: Perfect octave (12 semitones)
The natural minor scale has a minor 3rd, minor 6th, and minor 7th instead — that's what gives it the "sad" sound. Same notes, different intervals from the root, completely different feel.
For a deeper look at how modes change the interval pattern, see our modes guide.
Intervals in Chords
Chords are built by stacking intervals. Understanding this makes chord construction completely logical:
- Major triad: Root + Major 3rd + Perfect 5th (0–4–7)
- Minor triad: Root + Minor 3rd + Perfect 5th (0–3–7)
- Diminished triad: Root + Minor 3rd + Tritone (0–3–6)
- Major 7th: Root + Major 3rd + Perfect 5th + Major 7th (0–4–7–11)
- Dominant 7th: Root + Major 3rd + Perfect 5th + Minor 7th (0–4–7–10)
The difference between major and minor? One interval: the 3rd. Major 3rd (4 semitones) = happy. Minor 3rd (3 semitones) = sad. One semitone changes everything.
How to Practice Intervals
- Sing them. Pick a note and sing each interval up from it. Use the song references until you don't need them anymore.
- Identify them in songs. When you listen to music, try to name the interval between the first two notes of the melody. Start with simple melodies and work up.
- Play them on your instrument. Pick a root note and play each interval. Learn where they are on the fretboard or keyboard. For guitar, see our scale reference sheets which show interval patterns.
- Use an ear training app. Apps like Functional Ear Trainer or Tenuto play random intervals for you to identify. 10 minutes daily for a month makes a massive difference.
- Print a reference. Keep an interval chart in your practice book. Seeing the patterns on paper reinforces what your ears are learning.
Print an interval reference for your practice book
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Start Building a SongbookFrequently Asked Questions
What's the difference between melodic and harmonic intervals?
A melodic interval is two notes played one after another (like in a melody). A harmonic interval is two notes played at the same time (like in a chord). The distance is the same — the difference is just whether you hear them sequentially or simultaneously.
Why do some intervals sound pleasant and others harsh?
Intervals where the frequencies have simple ratios (like 2:1 for an octave, or 3:2 for a perfect fifth) sound consonant — stable and pleasant. Intervals with complex ratios (like the tritone at 45:32) sound dissonant — tense and unstable. Neither is better; music uses both for different effects.
How long does it take to learn to recognize intervals by ear?
Most musicians can reliably identify common intervals (perfect 5th, octave, major 3rd) within a few weeks of daily practice. Full interval recognition across all 13 intervals typically takes 2–3 months of regular ear training. Using song references (like 'Star Wars' for a perfect 5th) speeds up the process significantly.
Do I need to learn intervals to play music?
You can play music without formally knowing intervals — many excellent musicians do. But understanding intervals makes everything else in music theory click: why scales have their patterns, how chords are built, why certain notes sound good together, and how to transpose. It's the single most useful foundation to learn.
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