Banjo A♭ chord (Double C)A♭ major on the 5-string banjo: 0 1 0 1, and 6 more shapes

Frets, string 4 to string 1: 0 1 0 1 (open position)

1. String 4 (C): open, C
2. String 3 (G): 1st fret, index finger, A♭
3. String 2 (C): open, C
4. String 1 (D): 1st fret, middle finger, E♭
5. String 5, the short g: open, G, not in the chord

Sounds: C A♭ C E♭  ·  A♭ is A♭, C, E♭ (1 · 3 · 5)

Found in: C minor (♭VI), E♭ major (IV), D♭ major (V), A♭ major (I), B♭ mixolydian (♭VII), E♭ mixolydian (IV)

The 5th string: the short g rubs against the A♭ in this shape, a semitone away: some players let it ring, some skip it.

Double C tuning: gCGCD, the short 5th string first, then strings 4 to 1.