Modern pianos have 88 keys, but early versions had only 54.

The evolution of the piano began in 1700 when Bartolomeo Cristofori invented the 'gravicembalo col piano e forte' in Florence, Italy. His original instruments featured only 54 keys, covering four octaves. As the Classical and Romantic eras progressed, composers like Ludwig van Beethoven began writing music that exceeded these limits, forcing manufacturers to innovate.In the mid-19th century, companies like Broadwood and Erard began adding more keys to satisfy these musical demands. By 1888, the prestigious firm Steinway & Sons introduced the 88-key model, which eventually became the global benchmark. This specific number of keys provides a frequency range from 27.5 Hz (A0) to 4,186 Hz (C8).Scientifically, this range is optimized for the human auditory system. While humans can technically hear frequencies up to 20,000 Hz, the brain struggles to perceive distinct musical pitches above 4,000 to 5,000 Hz. Notes higher than the 88th key would sound like sharp, metallic clicks, while notes lower than the first key would be heard as rhythmic pulses rather than clear tones.The 88-key standard remains dominant because it balances manufacturing costs with the physical limits of string tension. Modern grand pianos must withstand over 20 tons of pressure from their strings. Adding more keys requires significantly larger cast-iron frames and complex engineering that offers little acoustic benefit to the average listener.