Intervals
Diminished Seventh
7d · 9 semitones
A seventh narrowed to the width of a major sixth — the interval that closes the diminished seventh chord.
Also written d7 · 7d
Diminished Seventh
7d · 9 semitones
On the piano, from every note
| From | Notes | Play it on your instrument |
|---|---|---|
| C | C – Bbb | |
| C# | C# – Bb | |
| D | D – Cb | |
| Eb | Eb – Dbb | |
| E | E – Db | |
| F | F – Ebb | |
| F# | F# – Eb | |
| G | G – Fb | |
| Ab | Ab – Gbb | |
| A | A – Gb | |
| Bb | Bb – Abb | |
| B | B – Ab |
Tap a key or a fret to hear it.
Read on: number and quality · inversion · consonance and dissonance
Every seventh
A seventh can take these qualities, one semitone apart; choose one to see the upper note move and hear the pair.
Understanding Diminished Seventh
Names and symbols
Diminished Seventh is written d7, 7d: the letter is the quality, the number the size. Chord formulas on this site write the number first, as tonal does.
Seconds, thirds, sixths and sevenths come in major and minor, a semitone apart, and can be widened to augmented or narrowed to diminished. Inverting one swaps the quality: a major third becomes a minor sixth, a minor second a major seventh.
How it sounds
A diminished seventh spans 9 semitones: C – Bbb. It sounds like a major sixth, and it is spelled as a seventh because it completes a stack of three minor thirds.
How composers use it
The diminished seventh chord divides the octave into four equal parts, so it belongs to no key and can resolve in any of four directions with equal plausibility. That ambiguity made it the standard nineteenth-century modulation device, and it is still the fastest way to pivot anywhere.
Learn this properly
Chapter 5: IntervalsCommon questions
- How many semitones is a Diminished Seventh?
- Nine — C – Bbb — the same distance as a major sixth. Count the semitones of any interval with the interval calculator.
- Why is a diminished seventh chord so useful for modulation?
- It splits the octave into four equal minor thirds, so it has no home key and can resolve convincingly in four different directions.
- How is it different from a major sixth?
- Not in sound. In spelling and function: the diminished seventh completes a stack of minor thirds, so its upper note is a seventh above the root by letter name.
- How do I play Diminished Seventh?
- On guitar the handiest shape is Next string, B 1 · E 5, read as string and fret; the instrument panel draws it from any starting note with the other shapes. On the piano count 9 semitones up from any key, black keys included. Play the notes together for the harmonic form, one after the other for the melodic form.
- What is the inversion of Diminished Seventh?
- The inversion of Diminished Seventh is the Augmented Second: put the lower note an octave higher and the distance that remains is the inversion. The two always add up to an octave, 9 semitones and 3 semitones, and swap their qualities between major and minor, or keep perfect as perfect.