How did Ludwig van Beethoven change the piano sonata?

Ludwig van Beethoven transformed the piano sonata by significantly expanding its scale and expressive power, moving the genre toward a more dramatic and almost symphonic character. While his early works followed the gracious and elegant style typical of the late 18th century, he eventually pushed the boundaries of the form by increasing the length of the exposition and enhancing the importance of the coda.12

Beethoven’s innovations were driven by both his evolving artistic vision and advancements in piano technology. As instruments became sturdier and capable of a wider range of expression, he composed pieces that were increasingly demanding, requiring formidable technical skill rather than the lighter touch expected of amateur players. Furthermore, while he retained the basic sonata form, he experimented with the use of unusual keys and, in his later works, began shifting away from the traditional dualistic sonata principle toward a more monistic approach, incorporating elements of variation and fugue. Through these changes, he established a new standard of excellence for the genre, influencing generations of composers who followed him.12