What are the differences between white keys and black keys on a piano?

Why do we have white and black keys?

Have you ever wondered why there are 7 white keys and only 5 black keys on a piano? Or what the differences were between them? Why we have them at all?

As a child, I remember having those questions, along with why 7 and 5? Should there be more black ones? Are there missing notes that just don’t sound good? 

At the time, it was explained to me as “the white ones sound happy, and the black ones sound sad.” Needless to say, this wasn’t a good enough explanation.

Another common explanation is “the white ones were made of ivory (like an elephant’s tusk), the black ones were made of ebony (a dark wood).” But again, that doesn’t really explain the difference.

Or Google’s best guess: “The white ones are whole tones, and the black ones are half steps up.” But what does that mean? And what makes a tone whole? In looking this one up, I also often ran into complex technical explanations that didn’t make much sense to me.

I’m going to try to explain it simply enough that anyone can understand, which requires looking at some basic ideas first. I’ll speed through them, as more detailed explanations exist elsewhere.

Let’s dive in.

The Basics of Sound

All sound is caused by vibration. When we think of sound, we usually think of vibrations in the air. You can hear through anything—it’s the vibrations. For example, you can hear underwater or with your ear pressed against a door. It’s still sound, just not through the air. The speed at which the vibration goes back and forth is called the “frequency.”

Different frequencies sound higher or lower. The faster the frequency, the higher the note. The lower the frequency, the lower the tone.

Take the average man’s voice. His vocal cords vibrate around 85-155 times per second to produce his voice. The average woman’s voice is closer to 165-255 vibrations per second. We all have a specific range that varies from person to person. And usually, you can increase your range with practice, but there is a physical limitation to the vocal cords.

Some specific frequencies are called notes. They are individual units of sound. On a keyboard, each key plays a different note. Being slightly off the specific frequency is called “off-key.” Setting an instrument to the correct frequency is called “tuning.”

Over the centuries, there have been some shifts in what the “correct” frequency was for different notes. Even today, there is some variation in what the correct frequency should be. But nowadays, they are all relatively closely tuned.

A piano makes sound when you press a key by having a little hammer inside hit a wire. Generally, the shorter wires vibrate faster, while the longer ones vibrate slower. Thicker wires vibrate more slowly and thinner ones vibrate faster, as well.

The further left the key is on the piano, the longer or thicker the wire inside, the slower the vibration, and the lower the note. The further to the right, the shorter or thinner the wire inside, the faster the vibration, and the higher the note.

There is a pattern in frequencies. Once the frequency doubles, it plays the same note again at a higher pitch. Each set of frequencies is called an octave.

So, we get recurring notes up and down in higher or lower octaves.

In music, we use 12 different notes in each octave. They are evenly spaced out and fit into the frequencies very evenly.

Each key on a piano keyboard represents one of the 12 notes in an octave. There isn’t anything special about them being white or black. Not if we are looking at what makes music.

Why are they black and white? Why 7 white keys and only 5 black ones?

It’s because there used to be only 7!

Way back in the day of the Ancient Greeks (around 2200 years ago), they used an instrument that only had 7 different keys on it’s keyboard. The notes they played all sounded good together. These became the white keys on the keyboard.

Over a thousand years later we got 5 new keys. These became the black keys. (Even though the colors were initially reversed!)

These new notes filled in the missing spaces in the octaves, and opened up music to tons of new flavors.

This brought music up to the current 12 notes per octave that all Western music uses.

Different sets of notes sound good together. The various sets change the emotion that you want to create in the listener. A cheerful song will use a handful of notes and specifically leave out certain notes. A song that is supposed to be sorrowful will use a few particular notes and leave out a couple of specific notes.

Going up or down the octave, each set uses the same notes only. A wrong note will sound off compared to the rest of the song.

The different sets of notes used are also called a key. There are 24 different keys. Most keys use a combination of white and black keyboard keys. The first ones, back in the ancient Greek days, were only white keys.


So, when we moved from a 7-note octave to a 12-note octave, we added tons of new musical combinations (keys). Many more unique combinations of notes and a much wider range of music and emotions could be played.

What is a "half-tone" or a "whole tone"?

“Half” is a bit of a misnomer. The 7 “whole” notes are not different than the between tones except in name.

The white keys play the “whole notes”. They are usually lettered A, B, C, D, E, F and G. (Or Do, Re, Mi, Fa, Sol, La, Ti, as in the Sound of Music.) The black keys are “half up” or “half down”. But all 12 of the notes are next to each other in the musical scale, and they are all as “whole”, or far apart as each other.

There are spots on a keyboard with two white keys next to each other, without a black in between. Technically those two white keys are as close as any white and black key are. But they are just given a new letter unto themselves.

It’s just easier to orient the white keys to letters. The black ones are all looked at as compared to the adjoining white ones.

Why use white and black keys at all?

They could have used 6 white and 6 black keys. It would have made more sense for “whole” and “half” notes.

A piano has many keys. 60, 70, 80, some even have more than a hundred keys! Having a really simple pattern to orient yourself with makes a huge difference. A pianist can sit down and with a short glance can orient themself to the whole instrument. Some do it without looking, by just feeling where they are.

If it was totally symmetrical you would have to learn every note by ear or would have to count all the keys each time!

That still leaves how much easier it is to write music if you can start with exactly which key to start from.

I hope this has been helpful. Check out the rest of the site for some more great resource. Like the Top 5 Ways to Learn to Play the Piano.

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