Why did the harpsichord and lute gradually disappear from the orchestra?

The harpsichord and lute were gradually phased out of the orchestra as musical styles and instrumentation evolved during the 18th century.1

The decline of these instruments was driven by several key factors:

• Rise of the Piano: By the mid-18th century, the harpsichord began to compete with the emerging pianoforte. Unlike the harpsichord, which produces a uniform volume regardless of touch, the piano allowed for dynamic gradation—the ability to play soft or loud based on the pressure applied to the keys—which became increasingly essential to the musical expression of the time.2
• Shift in Musical Style: The musical landscape moved away from the contrapuntal style of the Baroque era, which relied heavily on the basso continuo (often realized by a chordal instrument like the harpsichord or lute), toward a style focused on melodic invention supported by harmony.3
• Orchestral Development: As the symphony orchestra standardized its composition, composers began to favor instruments that offered greater tonal resources and volume, eventually rendering the specific roles of the harpsichord and lute obsolete within the ensemble.1