Perfect Fifth
Definition & Properties
The perfect fifth is one of the most harmonically pure intervals after the octave. Its powerful open consonance forms the foundation of Western harmony, power chords, and the circle of fifths.
| Property | Value |
|---|---|
| Abbreviation | P5 |
| Semitones | 7 |
| Quality | Perfect |
| Just Ratio | 3:2 |
| Cents from Equal | +1.96 |
| Harmonic Character | open consonance |
Ear Training Reference
The Perfect Fifth (P5) is commonly recognized by the ascending motion of: Twinkle Twinkle Little Star; Star Wars theme.
Practice direction: ascending — sing from the lower note up by 7 semitones.
Note Pair Examples
| Note 1 | Note 2 | Interval | Semitones |
|---|---|---|---|
| C | G | Perfect Fifth | 7 |
| G | D | Perfect Fifth | 7 |
| D | A | Perfect Fifth | 7 |
| F | C | Perfect Fifth | 7 |
Intonation by Temperament
The Perfect Fifth measures 3:2 in just intonation (+1.96 cents from equal temperament). This deviation affects ensemble tuning and instrument voicing.
| Temperament | C4 (Hz) | G4 (Hz) |
|---|---|---|
| Equal Temperament | 261.626 | 391.995 |
| Pythagorean | 260.740 | 391.111 |
| Just Intonation | 261.626 | 392.438 |
Instrument Tuning Context
The perfect fifth is the primary tuning interval for string instruments (violin, cello) and brass instruments. Pythagorean tuning is built from stacked perfect fifths.
Chords & Scales Containing This Interval
Chords
These chord types contain the Perfect Fifth as a characteristic interval:
Scales
These scales include the Perfect Fifth as a structural interval: