Perfect 5th

General info

Interval

Perfect 5th

Quality

Perfect

Semitones

7

Degree distance

5 degrees

Degree

5

Interval structure

Lower note

A (440.0 Hz)

Lower note role

Root

Upper note

E (659.3 Hz)

Upper note role

Perfect fifth (5)

Degree formula

I

V

Semitone formula

7 semitones (3.5 tones)

Interval construction

Interval formula

P5

Brief explanation

A perfect fifth spans seven semitones and is a perfect consonance. It belongs to major and minor triads and, together with the root, forms a power chord.

Interval notes

Consonance / dissonance

Sonority

Perfect consonance

Explanation

A perfect fifth is a perfect consonance. Without a third, it defines neither major nor minor quality, so the sonority sounds open and mode-neutral.

How the interval sounds

Tendencies & resolutions

As a consonance, a fifth requires no resolution by itself. Root motion by fifth has a separate role: V – I in the bass, usually up a fourth or down a fifth, forms the basis of an authentic cadence.

Harmonic context

The 5th is the interval between degrees I and V. It appears in maj and min triads, in 7, maj7, and m7 chords. The circle of fifths — the foundation of the tonal system — is built on a chain of 5ths. In power chords, the 5th is the only interval besides the root. In medieval music, parallel 5ths were the basis of polyphony (organum).

Interval inversion

Inverts to

Perfect 4thP4

Quality change

Perfect

perfect

Inversion rule

When inverting a perfect 5th, the lower note moves up an octave. 7 semitones (P5) become 5 semitones — a perfect 4th (P4).

Related intervals