Fdim piano chord, F diminished notes and fingering.

The Fdim piano chord is F diminished: the notes F, Ab and Cb. It is two minor thirds stacked on top of each other. F up to Ab is three semitones, and Ab up to Cb is three more, so the fifth (Cb) is lowered to six semitones above the root. Chord charts write it as Fdim or F°.

How to play Fdim on piano

1. Find F on the keyboard. F is the white key just left of the group of three black keys, next to E with no black key between them.
2. With your right hand, put finger 1 on F, finger 3 on Ab and finger 5 on Cb. Finger 1 is the thumb.
3. Press all three keys together. In root position they run from F4 to Cb5, a reach of 6 semitones. Play chord sounds them together and Arpeggio sounds them one by one, from the bottom up.
4. Click Left hand to see the left hand. It plays F3 to Cb4, one octave lower: F with finger 5, Ab with finger 3, Cb with finger 1.
5. The cards under the keyboard hold the three positions, with F, Ab and Cb at the bottom in turn. Play and Arpeggio on a card play that position.
6. Open Note names. As written the keys read F, Ab and Cb. Sharps shows F, G# and B, and Flats shows F, Ab and B. As written mixes sharps and flats on purpose, because each note takes its letter from its place in the chord.

How Fdim is built

Counted from the root, the formula is 0, 3, 6. Stacked on each other the gaps are 3 + 3: two minor thirds. Compare it with F minor (F, Ab and C): the first two notes are the same, and the fifth is lowered one semitone from C to Cb. A perfect fifth is seven semitones; this one is six, and six semitones is a tritone.

Worked example: the pitch of F4. On a piano tuned to A4 = 440 Hz, a note 4 semitones below A4 has the frequency 440 × 2^(-4/12), which is about 349.23 Hz. Ab4 is 1 semitones below A4, so 440 × 2^(-1/12) gives about 415.30 Hz.

What the keys look like under your hand

F has no black key on its left, because E and F are only a semitone apart, and F# is the black key on its right. One of the three notes is a black key (Ab) and two are white keys (F and Cb). Finger 3 presses Ab, a black key between G and A. The middle fingers are the longest, so they reach black keys most easily.

Fdim inversions and fingering

Fdim has three positions. In root position F is at the bottom. In the first inversion, Ab is at the bottom and the chord is written Fdim/Ab. In the second inversion, Cb is at the bottom and the chord is written Fdim/Cb. The tightest reach, 6 semitones from the lowest key to the highest, is the root position. The widest, at 9, is the first inversion and second inversion.

The keys that hold Fdim

Fdim fits two of the major and natural minor keys that have a standard key signature, which means every note of it comes from that key's scale. The simplest is Gb major, with 6 flats, where it is chord vii°.

Progressions that use Fdim, with the chord numbers and the chords in that key:

• Gb major: IV-vii°-iii-vi, which is Cb, Fdim, Bbm, Ebm, a run of falling fifths.
• Eb minor: ii°-v-i, which is Fdim, Bbm, Ebm, the minor ii-V-i, with the natural minor v.
• Gb major: vii°-I, which is Fdim, Gb, the diminished chord leading up to the tonic.

Here is a worked example in Gb major. The chord before Fdim in the first progression above is Cb (Cb, Eb and Gb). From Cb in root position, the closest way to reach Fdim is its second inversion (Cb, F and Ab, lowest note first): one note stays where it is, and the others move 4 semitones in total, counting each note against the note in the same place from the bottom.

Fdim also sits inside Db7 (Db, F, Ab and Cb): take the root off that dominant 7th and the notes left over are F, Ab and Cb.

What Fdim sounds like

A diminished triad sounds tense and unresolved. It rarely sits still: the usual move is up a semitone to the chord built on Gb. It is used as a passing chord between two others and as a spice inside a progression.

Fdim is the vii° chord in Gb major and the ii° chord in Eb minor.

A common mistake with Fdim

A common mistake is pressing C instead of Cb, one semitone higher than the fifth of Fdim. That gives Fm (F, Ab and C), a plain minor chord. The top key of Fdim is a semitone lower than you might expect, so check it against the chord of the same root.

Chords to learn next

Chords close to Fdim: F minor (raises the fifth; shares F and Ab); Db7 (the dominant 7th it sits inside; contains all its notes); Gb major, listed as F# major (the chord it leads to; shares no note); Fm7 (adds a minor seventh to the minor chord; shares F and Ab).

Once Fdim feels easy, play it and then Gb major to hear it resolve upward. For chords beyond these six types, and for guitar and ukulele shapes, use the chord finder. To play along with your computer keys, open the virtual piano. The piano chords page lists all 72 chords.