Interval · P5 · 7 half steps
The perfect fifth
A perfect fifth is 7 half steps wide, spanning five letter names: C to G. Strong, open and stable: Twinkle, Twinkle, Little Star.
- Half steps7
- Letter names5
- From CC–G
- Inverts toperfect fourth
The perfect fifth on the staff
An interval’s number counts letter names from the bottom note to the top, both included: C, D, E, F and G is five, a fifth. On the staff, both notes are on lines or both in spaces: from a line, it lands on the second line up (skipping the line between); from a space, on the second space up.
The number alone doesn’t make it a perfect fifth: perfect means exactly 7 half steps. Check for sharps and flats, including the key signature: C–G is a perfect fifth; move either note by a half step and it changes.
Each example below plays the two notes one after the other (a melodic interval), then together (a harmonic interval).
On the piano
Count half steps: every key, black or white, is one half step from the next. From middle C, the perfect fifth is the 7th key up, G.
In a five-finger position, thumb to little finger is a perfect fifth. Every white-key fifth is perfect except B–F, which is a half step narrower (the tritone).
On the white keys alone, the perfect fifths are C–G, D–A, E–B, F–C, G–D and A–E.
How a perfect fifth sounds
A perfect fifth is open, strong and stable. Its two notes blend so well that it sounds hollow rather than major or minor: it has no third to give it a colour. It’s the sound of a left hand’s open fifth, of bagpipe drones, and of the guitar’s power chord.
In harmony, it’s a perfect consonance: the two notes blend almost into one.
Tunes that start with it
- Twinkle, Twinkle, Little Star: the second “twin-kle” is a perfect fifth above the first (C to G).
- The main theme of Star Wars leaps up a perfect fifth after its quick opening notes.
Hum the tune’s first two notes and you have the interval: a quick way to sing one before you play it.
Where you’ll meet it
Every major and minor chord is built on a perfect fifth (C–G in C major and C minor), with the third in between. The left hand often plays root and fifth alone. Keys a fifth apart share all but one note, and a ring of fifths, the circle of fifths, orders every key signature.
Turned upside down, with the bottom note moved up an octave, a perfect fifth becomes a perfect fourth: 7 and 5 half steps make an octave, and the letter numbers always add up to nine (5 + 4).
To read it fast in real music, practise intervals the way you read words: as shapes. Level 6: fourths and fifths in the free sight-reading exercises has plenty of them.
Quiz: the perfect fifth
Ten questions: name the interval on the staff, among its neighbours, and play a perfect fifth above a written note on the piano below, a MIDI keyboard or your computer keys.
The quiz needs JavaScript.
A perfect fifth above every note
| From | A perfect fifth up |
|---|---|
| C | G |
| C♯ | G♯ |
| D | A |
| E♭ | B♭ |
| E | B |
| F | C |
| F♯ | C♯ |
| G | D |
| A♭ | E♭ |
| A | E |
| B♭ | F |
| B | F♯ |
Each one is spelt with the 5th letter up, which is why some need a sharp or flat that looks unusual, like C♯ up to G♯.
Questions
How many half steps are in a perfect fifth?
7 half steps. Count every key, black and white, from the bottom note up to the top one: C to G is a perfect fifth.
What is a perfect fifth above C?
G. It’s spelt with the 5th letter up from C (C, D, E, F and G).
What is the inversion of a perfect fifth?
A perfect fourth. Move the bottom note up an octave and the seven half steps become five: perfect fifth and perfect fourth add up to an octave.
How do you recognise a perfect fifth on the staff?
Both notes are on lines or both in spaces: from a line, it lands on the second line up (skipping the line between); from a space, on the second space up. That tells you the letter distance; then check the sharps, flats and key signature to tell perfect from augmented or diminished.
What song starts with a perfect fifth?
Twinkle, Twinkle, Little Star: the second “twin-kle” is a perfect fifth above the first (C to G).
Hear every interval in real music
Pianomi, a free sight-reading app for piano, writes new pieces at your level and listens to your MIDI keyboard, so intervals become shapes you read without counting.