Pitch & Intervals
Diminished Interval
Written as d
A diminished interval is one half step smaller than a perfect or minor interval with the same letter names, such as the diminished fifth B–F or the diminished seventh B–A♭.
A diminished interval is a perfect or minor interval squeezed by one half step without changing its letter names. It is abbreviated d (or "dim"): d4, d5, d7.
- Minor 3rd C♯–E (3) becomes diminished 3rd C♯–E♭ (2)
- Perfect 4th C♯–F♯ (5) becomes diminished 4th C♯–F (4)
- Perfect 5th C–G (7) becomes diminished 5th C–G♭ (6)
- Minor 7th C–B♭ (10) becomes diminished 7th C–B𝄫 (9)
- Perfect octave C–C (12) becomes diminished octave C–C♭ (11)
The number stays the same because the letters do. B–A♭ spans seven letter names (B C D E F G A), so it is a 7th, even though it covers only nine half steps, the size of a major 6th. Intervals like these, with the same sound and different names, are enharmonic equivalent.
Where diminished intervals appear
- Diminished 5th: the tritone from the 7th up to the 4th degree of a major scale (B–F in C major), and the outer interval of the diminished triad B–D–F.
- Diminished 7th: the outer interval of the diminished seventh chord, such as B–D–F–A♭ in C minor, built on the leading tone of the harmonic minor scale.
- Diminished 4th: also from harmonic minor, from the leading tone up to the 3rd degree (G♯–C in A minor), an expressive leap often heard in Baroque melodies.
- Diminished 3rd: the inversion of the augmented 6th, found inside augmented sixth chords.
Spelling them
Count letters first, then adjust. For a diminished 7th above C♯: seven letters up from C♯ is B. C♯–B is a minor 7th (10 half steps), so lower the B: C♯–B♭, nine half steps. Above C you need a double flat: C–B𝄫.
Inversion
A diminished interval inverts to an augmented one: the diminished 5th B–F becomes the augmented 4th F–B, and the diminished 7th B–A♭ becomes the augmented 2nd A♭–B.
Diminished intervals sound tense, and they tend to resolve by narrowing, the way B–F closes in to C–E. Practice them with Name the intervals: the full toolkit and Write the intervals.
Common questions
What is a diminished interval?
An interval one half step smaller than a perfect or minor interval with the same letter names. C–G is a perfect 5th; C–G♭ is a diminished 5th.
How many half steps are in a diminished seventh?
Nine, the same as a major sixth. It is a minor 7th (10 half steps) made one half step smaller, as in B–A♭ or C–B𝄫.
Practice it: free worksheets
Name the intervals: the full toolkitThe complete quality kit. P = perfect (the natural size of 4ths and 5ths: P4 = 5 half steps, P5 = 7). A = augmented, a half step wider than major or perfect. d = diminished, a half step narrower than minor or perfect. Write e.g. M3, m2, P4, A2, d5.
Write the intervalsEach staff gives you the bottom note. In the empty bar, write the note that is the named interval above it, as a whole note. First count letters to find the right line or space, then count half steps and add a sharp or flat if the size is not right yet.
Double sharps and double flatsA sharp raises a note one half step; a flat lowers it one (Handouts 06–08). Now and then a note has to move two. The double sharp raises it two half steps, the double flat lowers it two. The key you play is one you already know — only its name is new.
IntervalsEvery interval from a unison to an octave, measured up from C. Two counts name any interval: count the letters (both ends) for the number, then count the half steps for the quality (Handouts 04 and 05). Each figure shows the interval one note after the other, then together.
Intervals: the 5thThe biggest interval in your five-finger world: the 5th — five letters from bottom to top, like C up to G. You already know this pair by another name.