F diminished (Fdim) chord on mandolin

The F diminished chord (Fdim) is a diminished triad (two minor thirds), made of three notes: F – A♭ – C♭.

Dots show:

Basic shapemedium

Position 4medium

Position 6medium

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What the Fdim chord sounds like

A diminished triad is two stacked minor thirds with a diminished fifth. It sounds tense and unsettled; in a major key it sits on degree vii and leads into the tonic.

Notes of the Fdim chord

Degree	Note	Interval from the root
1	F	root
3	A♭	minor third (3 semitones)
5	C♭	diminished fifth (6 semitones)

How to play it – with fingering

Basic shape

String 1 (E): fret 1, middle finger (F5)
String 2 (A): fret 2, ring finger (C♭5)
String 3 (D): fret 3, little finger (F4)
String 4 (G): fret 1, index finger (A♭3)

Position 4

String 1 (E): fret 4, middle finger (A♭5)
String 2 (A): fret 8, little finger (F5)
String 3 (D): fret 6, ring finger (A♭4)
String 4 (G): fret 4, index finger (C♭4)

Position 6

String 1 (E): fret 7, middle finger (C♭6)
String 2 (A): fret 8, ring finger (F5)
String 3 (D): fret 6, index finger (A♭4)
String 4 (G): fret 10, little finger (F4)

Tuning: G D A E, like a violin; every note is a pair of strings that you fret together. In the diagram, × means the string is not played, and a circle means an open string.

Which keys is it in?

The Fdim chord is built from the notes of these keys (for minor keys, both the natural and the harmonic minor are considered):

G♭ major: vii°
E♭ minor: ii°

Similar chords and substitutes

If Fdim is too hard, or you want a different colour in the same spot, these chords are worth a try.

Substitutes (by function)

C♯7 – an incomplete dominant: the diminished chord is the top of this seventh chord
F♯ – where it leads (leading tone → root)

Richer versions

Fdim7 – the same chord plus 1 colour note
Fm7b5 – the same chord plus 1 colour note

Frequently asked questions

What notes are in the Fdim chord?

F, A♭, C♭. The root is F; the intervals of the other notes from the root: minor third, diminished fifth.

What is the easiest way to play Fdim on mandolin?

The easiest shape above is “Basic shape”. We show 3 shapes, from open and easy versions to movable barre shapes higher up the neck.

How do I read the chord diagram?

Strings run from the lowest (left) to the highest (right) – tick “Left-handed” to mirror it. Rows are frets; a number at the side shows the starting fret. Dots are fingers (1 index, 2 middle, 3 ring, 4 little), a long bar is a barre, × means don't play that string and ○ means play it open.

How is the Fdim chord written?

The chord symbol is Fdim, and its full name is F diminished.