How many semitones is a Diminished Third?

Two — C – Ebb — the same distance as a major second. Count the semitones of any interval with the interval calculator.

When does a diminished third appear?

In chromatic harmony, particularly around augmented sixth chords and altered dominants, where spelling has to track function rather than sound.

How do I play Diminished Third?

On guitar the handiest shape is Next string, A 3 · D 0, read as string and fret; the instrument panel draws it from any starting note with the other shapes. On the piano count 2 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 Third?

The inversion of Diminished Third is the Augmented Sixth: put the lower note an octave higher and the distance that remains is the inversion. The two always add up to an octave, 2 semitones and 10 semitones, and swap their qualities between major and minor, or keep perfect as perfect.

Diminished Third Interval: How It Sounds, with Song Examples

Play it on your instrument

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From

On the piano, from every note

From	Notes	Play it on your instrument
C	C – Ebb
C#	C# – Eb
D	D – Fb
Eb	Eb – Gbb
E	E – Gb
F	F – Abb
F#	F# – Ab
G	G – Bbb
Ab	Ab – Cbb
A	A – Cb
Bb	Bb – Dbb
B	B – Db

Tap a key or a fret to hear it.

Number and quality

An interval has two names. The number counts the letter names from the lower note to the upper one, and the quality counts the semitones inside that number. Diminished Third spans 3 letter names, which makes it a third, and 2 semitones, which makes it diminished.

DLetter
2 semitones

Read on: number and quality · half steps and whole steps · inversion · compound intervals · consonance and dissonance

Every third

A third can take these qualities, one semitone apart; choose one to see the upper note move and hear the pair.

Where it lives

Diminished Third is in every chord whose formula includes 3d from the root, in every scale that includes it from the tonic, and between these pairs of notes in a major key.

Related intervals

The intervals one step from Diminished Third: its inversion, the same sound spelled differently, its simple or compound form, and its nearest neighbours in size.

Augmented Sixth6A · 10 semitones · C – A#
Inversion: together they make an octave
Major Second2M · 2 semitones · C – D
The same sound, spelled differently
Diminished Tenth10d · 14 semitones · C – Ebb
The compound form, an octave wider
Minor Second2m · 1 semitone · C – Db
One size away
Minor Third3m · 3 semitones · C – Eb
One size away

Open it in a tool

Understanding Diminished Third

Names and symbols

Diminished Third is written d3, 3d: 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 third spans 2 semitones: C – Ebb. It sounds like a major second, and it is written as a third because both notes are functioning as chord tones a third apart.

Where it comes from

It appears between the raised fourth and the flattened sixth in chromatic voice leading, and in the augmented sixth chords — where the outer voices resolve outward to the octave and the inner spelling has to follow.

Learn this properly

Chapter 5: Intervals

Common questions

How many semitones is a Diminished Third?: Two — C – Ebb — the same distance as a major second. Count the semitones of any interval with the interval calculator.
When does a diminished third appear?: In chromatic harmony, particularly around augmented sixth chords and altered dominants, where spelling has to track function rather than sound.
What is its inversion?: The Augmented Sixth.
How do I play Diminished Third?: On guitar the handiest shape is Next string, A 3 · D 0, read as string and fret; the instrument panel draws it from any starting note with the other shapes. On the piano count 2 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 Third?: The inversion of Diminished Third is the Augmented Sixth: put the lower note an octave higher and the distance that remains is the inversion. The two always add up to an octave, 2 semitones and 10 semitones, and swap their qualities between major and minor, or keep perfect as perfect.