Basses are found on the left-hand side of piano accordion. They are repeated in columns and rows that are evenly distributed. Any of the bass is played with the fingers of left hand.

Basses located in the first two columns from the bellows are used to play the single tones. They may be basic and auxiliary. Auxiliary basses are found in the first column and basic basses in the second column.

In other three columns that are not marked there are basses used to play chords. The basic chords are major, minor and chord seventh.

The number of basses in a row multiplied by the number of basses in a column gives the total number of basses on the accordion that may vary between the models of accordion. The basses of piano and button accordions are played in the same way.

The presentation below shows distribution of 120 bass keys with the marks of the additional and basic tones.

 left-hand side