Interval reference
Diminished fifth
5 letter names · 6 semitones · C → G♭
A diminished fifth spans 5 letter names and 6 semitones. Both halves of that description matter: the number comes from the letters, the quality from the exact size.
Starting on C, a diminished fifth reaches G♭. Its shorthand is d5, and traditionally it counts as dissonance.
How big it is
Hear it from any note
The explorer starts on C up to G♭. Play it one note after the other and then both together — the two ways a diminished fifth turns up in music — then change the bottom note: the distance stays the same while the spelling follows the letters.
Turned upside down
Move the lower note up an octave and a diminished fifth becomes an augmented fourth. The two numbers add up to nine, and the quality flips — major with minor, augmented with diminished, while perfect stays perfect.
Where you meet it
- The third of a dominant seventh chord up to its seventh (B up to F in G7)
- The root to the fifth of a diminished triad (B up to F in B diminished)
From every starting note
| From | Up a diminished fifth |
|---|---|
| C | G♭ |
| C♯ | G |
| D | A♭ |
| D♯ | A |
| E | B♭ |
| F | C♭ |
| F♯ | C |
| G | D♭ |
| G♯ | D |
| A | E♭ |
| A♯ | E |
| B | F |