Perfect fourth
A perfect fourth is 5 half steps: from C up to F. Open and strong but not quite at rest, like a call to attention.
The perfect fourth at a glance
| Perfect fourth | |
|---|---|
| Half steps | 5 (two and a half whole steps) |
| Letters it spans | 4: C D E F |
| Short name | P4 |
| Inverts to | Perfect fifth |
| Frequency ratio | 1.335 on a piano, 4:3 in just intonation |
Every note’s frequency in hertz is on the note frequency chart.
Songs that start with a perfect fourth
Going up: "Here Comes the Bride" (Wagner’s Bridal Chorus) and "Amazing Grace" ("A-ma").
Sing the tune’s first notes in your head and you have the interval from any starting note.
The perfect fourth in chords
The 4 of a sus4 chord (C to F in Csus4), and the gap from a chord’s fifth up to its root, G to C in C major.
Every chord’s notes, to hear on a keyboard, are on piano chords.
A perfect fourth from every note
| From | Up a perfect fourth |
|---|---|
| C | F |
| C♯ | F♯ |
| D | G |
| E♭ | A♭ |
| E | A |
| F | B♭ |
| F♯ | B |
| G | C |
| A♭ | D♭ |
| A | D |
| B♭ | E♭ |
| B | E |
Questions about the perfect fourth
What is a perfect fourth in music?
A perfect fourth is 5 half steps: from C up to F. Open and strong but not quite at rest, like a call to attention.
Why is a fourth called perfect?
Fourths, fifths, unisons and octaves are called perfect because they sound pure and have no major or minor form: made a half step smaller or larger, they become diminished or augmented.
What songs start with a perfect fourth?
"Here Comes the Bride" (Wagner’s Bridal Chorus) and "Amazing Grace" ("A-ma").
What is the inversion of a perfect fourth?
A perfect fifth. Move the lower note up an octave and a perfect fourth becomes a perfect fifth: their half steps add up to twelve.
Other intervals
All of them side by side, with how to name one, are on the interval chart.
Put intervals in a song
Open the free editor with a beat playing, then draw a melody note by note in the piano roll and hear every leap. No account needed to start.
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