Music intervals explained
An interval is the distance between two notes. Tap any key on the ruler below to hear the interval it makes with middle C and see how it is counted.
Perfect 5th
C4 → G4 · 7 semitones · 5 letter names counted
The wave shows both notes added together over a short stretch of time. Simple ratios like 3:2 repeat quickly, which the ear hears as smooth; complex ones like 45:32 take much longer to line up and sound tense.
How to name an interval in two steps
- Count the letters from the bottom note to the top, including both. C up to G is C-D-E-F-G: five letters, so it is a 5th. Accidentals do not change this number: C to G♯ is still a 5th.
- Count the semitones to get the quality. 2nds, 3rds, 6ths and 7ths come in major and minor; unisons, 4ths, 5ths and octaves are perfect. One semitone wider than major or perfect is augmented; one narrower than minor or perfect is diminished.
Interval chart
| Semitones | Interval | From C | Ratio (just) | Ascending song | Descending song |
|---|---|---|---|---|---|
| 0 | Unison (P1) | C–C | 1:1 | The same note repeated | — |
| 1 | Minor 2nd (m2) | C–D♭ | 16:15 | Jaws theme | Für Elise |
| 2 | Major 2nd (M2) | C–D | 9:8 | Happy Birthday | Mary Had a Little Lamb |
| 3 | Minor 3rd (m3) | C–E♭ | 6:5 | Greensleeves | Hey Jude |
| 4 | Major 3rd (M3) | C–E | 5:4 | When the Saints Go Marching In | Swing Low, Sweet Chariot |
| 5 | Perfect 4th (P4) | C–F | 4:3 | Here Comes the Bride | O Come, All Ye Faithful |
| 6 | Tritone (TT) | C–F♯ | 45:32 | The Simpsons theme / "Maria" | YYZ (Rush) intro |
| 7 | Perfect 5th (P5) | C–G | 3:2 | Twinkle Twinkle Little Star | The Flintstones |
| 8 | Minor 6th (m6) | C–A♭ | 8:5 | The Entertainer (the leap) | Love Story theme |
| 9 | Major 6th (M6) | C–A | 5:3 | My Bonnie Lies Over the Ocean | Nobody Knows the Trouble I’ve Seen |
| 10 | Minor 7th (m7) | C–B♭ | 16:9 | Star Trek (original series) | An American in Paris |
| 11 | Major 7th (M7) | C–B | 15:8 | Take On Me (chorus) | I Love You (Cole Porter) |
| 12 | Octave (P8) | C–C | 2:1 | Somewhere Over the Rainbow | Willow Weep for Me |
Ratios are the simple whole-number versions from just intonation. Modern instruments use equal temperament, where every semitone is exactly the twelfth root of 2, so all intervals except the octave are a few cents off these ratios. The difference is small enough that the character of each interval survives.
Consonance and dissonance
Octaves, 5ths and 4ths are the most consonant (stable); 3rds and 6ths are sweet “imperfect” consonances; 2nds, 7ths and the tritone are dissonant and tend to resolve. Hearing this stability ranking is a big part of recognising intervals by ear.
The ruler above is our take on learning by poking at something until it clicks. If that style suits you, ahaboo has narrated interactive explainers on how everyday things work, from why the seasons happen to how compound interest grows.
Ready to train your ear? The interval trainer plays random intervals for you to name.
Questions
What is an interval in music?
An interval is the distance in pitch between two notes. It has a number (count the letter names from the lower to the upper note, including both) and a quality (perfect, major, minor, augmented or diminished) determined by the exact number of semitones.
Why are some intervals “perfect”?
Unisons, 4ths, 5ths and octaves are called perfect because their frequency ratios are very simple (1:1, 4:3, 3:2, 2:1) and they sound especially stable. They have no major or minor versions, only perfect, augmented and diminished.
How many semitones are in a perfect fifth?
Seven. For example, C up to G. In just intonation its frequency ratio is 3:2; in equal temperament it is very slightly narrower.
What is a tritone?
A tritone spans six semitones, exactly half an octave, for example C to F♯ (an augmented 4th) or C to G♭ (a diminished 5th). It sounds restless and was nicknamed “diabolus in musica” in later music theory writing.
What is interval inversion?
Inverting an interval moves the lower note up an octave. The numbers add up to 9 and the quality flips: a major 3rd becomes a minor 6th, a perfect 4th becomes a perfect 5th, and major becomes minor.
What is the difference between a major and minor interval?
A minor interval is one semitone smaller than the major interval with the same number. C to E is a major 3rd (4 semitones); C to E♭ is a minor 3rd (3 semitones).