Perfect fifth: hear it and recognise it by ear
Play the perfect fifth up, down and together, learn the songs that start with it, then train your ear to recognise it.
A perfect fifth is the distance of 7 semitones between two notes, such as C up to G. It sounds open, stable and bright, and it is the jump at the start of "Twinkle, Twinkle, Little Star" (between the second and third notes).
Listen to a perfect fifth
C to G: 7 semitones.
What does a perfect fifth sound like?
Open and hollow, very stable. Played together, the two notes blend so well that they can sound like one rich note: guitarists call it a "power chord".
Songs that start with a perfect fifth
| Song | Direction | Where |
|---|---|---|
| Twinkle, Twinkle, Little Star | Up | between the 2nd and 3rd notes |
| Star Wars (Main Title) | Up | from the 1st long note up to the 2nd, after the quick three-note pickup |
Titles only. Each melody's opening was checked note by note; songs we were not sure of are left out.
How do you recognise a perfect fifth by ear?
- Sing the first two different notes of "Twinkle, Twinkle" in your head: if the jump matches, it's a fifth.
- A fifth is bigger than a fourth (5 semitones) and smaller than a minor sixth (8). Compare it with both.
- Played together, a fifth has no major or minor colour: it is neither happy nor sad.
Quick test: perfect fifth or not?
Four sounds. Each one is a perfect fifth or one of the intervals people confuse it with. Listen, then pick.
Score: / 4 (your score updates as you answer)
The perfect fifth on every note
Intervals are spelled by letter: a perfect fifth always spans 5 letter names, which is why the top note is sometimes a sharp or a flat.
| From | Perfect fifth up | Hear it |
|---|---|---|
| C | G | |
| D♭ | A♭ | |
| D | A | |
| E♭ | B♭ | |
| E | B | |
| F | C | |
| F♯ | C♯ | |
| G | D | |
| A♭ | E♭ | |
| A | E | |
| B♭ | F | |
| B | F♯ |
Perfect fifth in numbers
| Measure | Value |
|---|---|
| Semitones | 7 |
| Size on a piano (equal temperament) | 700 cents |
| Pure (just) ratio | 3:2 = 702.0 cents |
| Piano vs pure | -2.0 cents |
| Inversion | Perfect fourth (5 semitones) |
Frequently asked questions
How many semitones are in a perfect fifth?
Seven. Count every key on a piano, black and white, from C up to G: C#, D, D#, E, F, F#, G is 7 steps.
What is a perfect fifth above C?
G. Above D it is A, above E it is B, and above B it is F sharp.
Why is it called perfect?
The two notes vibrate at a ratio close to 3:2, one of the simplest ratios after the octave, so they blend smoothly. On a modern equal-tempered piano the fifth is 700 cents, about 2 cents narrower than the pure 3:2 fifth (702 cents), a difference almost nobody can hear.
What is the inversion of a perfect fifth?
A perfect fourth: C up to G is a fifth, G up to the next C is a fourth. Together they make an octave (7 + 5 = 12 semitones).