One of the most common questions we get from our clients is how many keys a piano has. …and, though most of today’s pianos have 88 keys (52 white keys and 36 black keys), it wasn’t always this way. The first pianos had 49 keys or 4 “octaves” (An “octave” is a group of 8 notes between and including two notes of the same name such as “Middle C” and “The C above Middle C”, etc.). As the instrument’s popularity grew, however, composers quickly found themselves limited by the 49 key keyboard. So, to increase the piano’s appeal for composers like Hayden and Mozart (who were writing primarily for the 60 note harpsichord), piano builders developed new 61 note or 5 “octave” pianos. By the mid 1800s, composers like Chopin and Liszt were writing for pianos with 85 notes or 7 “octaves.” Finally, in the late 1880s, Steinway & Sons created an 88 note or 7 1/3 octave piano and – due to Steinway’s popularity at the time – other manufacturers quickly followed suit. Today, the 88 note piano is still considered standard, but not all piano builders follow this standard. Bosendorfer, for example, offers two models with more than 88 keys. The Model 225 Bosendorfer piano has 92 keys and the Model 290 “Imperial” grand piano has a full 8 octaves or 97 keys. This choice was made to better support piano transcriptions of J.S. Bach’s famous organ works. Other compositions by Busoni, Bartók, and Ravel, can only be performed on these larger instruments.
…but why did the piano industry decide on 88 notes as the standard?
It has to do with how the human ear hears acoustic vibrations. Notes pitched lower than the standard 88 note piano keyboard are hard for the human ear to distinguish. Notes pitched higher than the piano keyboard have such short wavelengths, the human ear can barely hear them. Thus, due mainly to the limitations of human hearing, most composers today write music for 88 note pianos. Though piano builders are always experimenting with technologies that might expand the instrument’s range, for now the standard piano has 88 keys… and that is not likely to change any time soon.