Perfect fifth
（重定向自Open fifth）
![Perfect fifth Play equal tempered and Play just.](/Images/godic/202501/31/Perfect_fifth_on_C2449.png")
![Examples of perfect fifth intervals](/Images/godic/202501/31/Perfect5s2449.PNG")
![Just perfect fifth on D Play . The perfect fifth above D (A+, 27/16) is a syntonic comma (81/80 or 21.5 cents) higher than the just major sixth above middle C: (A♮, 5/3).[9]](/Images/godic/202501/31/Just_perfect_fifth_on_D2449.png")
![Just perfect fifth below A Play . The perfect fifth below A (D-, 10/9) is a syntonic comma lower than the just/Pythagorean major second above middle C: (D♮, 9/8).[9]](/Images/godic/202501/31/Just_perfect_fifth_below_A2449.png")
In music theory, a perfect fifth is the musical interval corresponding to a pair of pitches with a frequency ratio of 3:2, or very nearly so.
In classical music from Western culture, a fifth is the interval from the first to the last of five consecutive notes in a diatonic scale. The perfect fifth (often abbreviated P5) spans seven semitones, while the diminished fifth spans six and the augmented fifth spans eight semitones. For example, the interval from C to G is a perfect fifth, as the note G lies seven semitones above C. Play