To put that in perspective, Haydn wrote 68 string quartets, over ten times more than Xavier Richter and nearly triple that of Mozart and Beethoven(16). Haydn's musical output was astonishing and unmatched by any of his peers.

How many Haydn quartets are there?

Joseph Haydn wrote sixty-eight string quartets. (The number was previously thought to be eighty-three, but this includes some arrangements and spurious works.)

How many quartets did Mozart write?

Mozart completed some 26 string quartets, the first in 1770, at the age of fourteen, and the last in June 1790, the year before his death, when he wrote the first three quartets of a proposed set of six for the King Friedrich Wilhelm II of Prussia.