Fdim chordF diminished

String 6: not played
String 5: fret 8, finger 1 (index)
String 4: fret 9, finger 2 (middle)
String 3: fret 10, finger 4 (pinky)
String 2: fret 9, finger 3 (ring)
String 1: not played

Fdim (F diminished) has a dark, tense sound. Notes: F – Ab – B.

How to play Fdim

× muted string · ○ open string · numbers are fingers (1 index, 2 middle, 3 ring, 4 pinky)

💻 Learn it by playing in the app

The chord check listens and tells you which string is muted

Note	F	Ab	B
Interval	1 (root)	♭3 (minor 3rd)	♭5

Press with your fingertips as close to the fret as you can; you need less force for a clean sound.
Pick each string on its own and listen for muted strings; a finger touching the next string is the usual cause.
Press, release, press again: if you can form Fdim cleanly 20 times in a minute, you have it.