Why Do Pianos Have 88 Keys?

A standard piano has 88 keys: 52 white and 36 black. But who decided this number would be the standard? And perhaps most importantly, why?

To answer both these questions we must look to the past. To when the first piano was invented, by Bartolomeo Cristofori around the year 1700.  The Italian instrument technician decided it was time to update the restrictive harpsichord, the ancient ancestor of the piano, in favour of a new keyboard instrument which would be equipped with a hammer mechanism.

After Cristofori’s invention, composers started writing more and more music for the newly named ‘pianoforte’ instrument. But the instrument’s four-octave range (retaining the 66 keys from the harpischord) was limiting, with composers being confined to writing music that stuck within the four octave range. As a result, piano manufactuers designed new pianos with more keys, so that composers like Haydn and Mozart could write more interesting material with a wider range.

By the time composers such as Chopin and Liszt were righting music in the mid 1800s, pianos had up to seven octaves. But it wasn’t until the late 1880s before piano manufacturer Steinway created the 88-key piano. Other manufacturers followed suit, adding slight variations and enhancements but Steinway’s model has been the standard ever since.

Picture of Steinway's Grand Piano

Steinway’s Grand Piano from 1935

An 88-key piano has seven octaves plus three lower notes (B, B flat and A) below the bottom C. It has 52 white keys and 36 black keys (sharps and flats), with each octave made up of seven white keys and five black keys.

So, (you may be asking) why did manufactures stop at 88 keys? Well, today’s composers usually write piano music that fits within the range of an 88 key model. Most piano makers also accept this as the limit as anything outside of this range is considered too high or low for the human ear. There are however exceptions, for instance a Stuart and Sons piano held a staggering 102 keys. These pianos are rare and, unsurprisingly, are very expensive with valuations reaching as much as $300,000 USD (£226,000).