Perfect fourth
The perfect fourth spans 5 semitones and 4 steps (C–F). Inversion: perfect fifth. To remember it: »Amazing Grace« or »Hark! The Herald Angels Sing«, the first two notes.
- Semitones
- 5
- Steps
- 4
- Quality
- perfect
- Inversion
- perfect fifth
- Sound
- perfect consonance
In notation
First one after the other, then together — the distance as a step and as a sound.
On the keyboard
On the guitar: 5 frets higher on the same string.
How to count it
Counting 4 steps up from C — C, D, E, F — lands on F. The number of steps gives the name: a fourth. In between lie 5 semitones — the perfect size; one semitone less would be diminished, one more augmented.
Move the lower note up an octave and what remains is the perfect fifth: semitones add up to twelve, steps to nine.
Perfect consonance — the sound is at rest; in strict counterpoint it is treated as a dissonance against the bass.
To remember it
»Amazing Grace« or »Hark! The Herald Angels Sing«, the first two notes.
Where it occurs
In these chords it lies between the root and another note: Csus4.
Related
In the glossary: fourth · Ear training: hear intervals and guess them · All intervals
Anotona does this for you
Photograph a page of sheet music or play the melody — Anotona finds the key, engraves the notes and transposes them into any other. Free.
See AnotonaEvery note on this page is computed, not typed in — following the rule that also makes F# major spell its seventh degree E#, not F.