How many keys are on a piano? Black and white facts of the classic instrument.

The piano is a favorite instrument for experienced musicians and beginners alike, but it has changed in the digital age. Approximately 234,000 digital pianos were sold in 2021, a 24% increase from 2020. Gone are the days of needing a state-of-the-art grand or an upright piano – you can now play a pocket-size piano on your smartphone or buy a folding keyboard to take with you on the go.

Whether you’re a novice or have been tickling the ivories for years, here's a refresher on some facts about the piano:

How many keys are on a piano?

A typical piano has 88 keys spanning just over seven octaves. There are other, smaller keyboards or synthesizers that have fewer keys – most come in increments of 25, 32, 49, 61 or 72 keys.

According to Yamaha, the reason for the 88 keys has to do with the hearing capacity of the human ear: We can hear sounds in the range of 20 to 20,000 hertz, but we stop being able to discriminate frequencies around 4,000 hertz.

The lowest key on a keyboard registers at around 27.5 hertz and the highest at 4,186 hertz, depending on the precise tuning. Adding more keys wouldn’t add too much value to the piano because it would be outside the limits of the human ear.

Bartolomeo Cristofori invented the piano around the year 1700 after he wanted an instrument with more volume control than the harpsichord. One of Cristofori's three surviving pianos is at the Metropolitan Museum of Art in New York, and it has only 54 keys.

How many octaves are on a piano?

There are seven octaves on a standard piano, with three extra keys at the bottom – B-flat, B and C. An octave is a series of eight notes (C, D, E, F, G, A, B and C, in the C major scale). Different sizes of keyboards have varying octaves, depending on how many total keys they have:

• 49 keys with four octaves;

• 61 keys with five octaves;

• 76 keys with six and a half octaves;

• 88 keys with seven and a quarter octaves.

How many black keys are on a piano?

There are 36 black keys on a standard 88-key piano. The black keys represent sharps and flats.

How many white keys are on a piano?

A standard piano with 88 keys has 52 white keys. The white keys are the natural notes.

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This article originally appeared on USA TODAY: How many keys are on a piano? Learn the black and white standard.