Perfect fifth

The musical interval of a perfect fifth is the relationship between the first note (the root or tonic) and the fifth note in a major scale.

It can be produced by starting on a high note and playing the fifth below or by starting on a low note and playing the fifth above.

An "ideal" perfect fifth in just intonation corresponds to a pitch ratio of 2:3 or 1:1.5

In an equal tempered tuning, a perfect fifth is equal to seven semitones, a ratio of 1:2^7/12 or approximately 1.4983.

See also:

• perfect fourth
• musical tuning