The Different Parts Of An Accordion: Anatomy and Structure Explained

Written by Dan Farrant
Last updated

Ever wondered how an accordion works? You wouldn’t be the first. This incredibly unique instrument doesn’t operate like familiar stringed or brass instruments might. So what’s actually inside an accordion?

In this article, we’ll go over the different parts of an accordion. Inside the weird slinky-like instrument are a whole host of bits and bobs sure to tickle your fancy. 

Keep reading to learn more about the accordion’s construction, whether you’re looking to learn how to play or simply curious as to how it works.

Anatomy of an Accordion

Anatomy of an Accordion

While there is some variety in the types of accordions you might find on the market, the two most popular forms are the piano accordion and the button accordion. 

Piano accordions have a keyboard on the right, whereas button accordions feature a series of buttons instead.

As a result, button accordions can carry a much wider range of notes than a piano accordion.

While the two have different interfaces, they still share many of the same parts.

Here are the parts you’ll find in any modern accordion, piano or button style:

  • Keys/Buttons
  • Reeds
  • Bellows

There are smaller parts than the three we listed, and we’ll go through each part of an accordion in detail below.

Keep reading to learn how an accordion’s parts cooperate to produce the instrument’s unique sound.


Accordions feature a series of keys or buttons that control airflow through the reeds, resulting in playable notes.

These are the main parts of the instruments that the accordionist uses to control their music’s tonal quality directly. 

Each button extends itself inside the accordion bellows, covering a small hole that leads to the reeds.

The hole is uncovered when the player depresses one of the keys, allowing air through and out the reeds. 

The interface can also switch out the type of reeds in position over the hole.

As a result, you can change the tonal quality even further when you switch between reed types and button strokes. 

Many of the accordion’s keys and buttons aren’t within the player’s field of vision, meaning you’ll have to memorize their position if you want to get serious with this instrument. 


Piano accordions essentially have a mini keyboard attached to the instrument’s treble end.

While it doesn’t usually contain the same number of notes as a full-sized piano, the accordion’s keyboard has anywhere between 25 and 45 treble keys, depending on its size. 

All piano keys are treble keys on most modern keyboard accordions, balanced by a larger array of bass buttons.

The keyboards are typically located on the instrument’s right side, but you may find some specialty instruments that have them on the left.

The keys directly control the valves that release air through the reeds when the player compresses and decompresses the bellows.

However, you typically can’t see all the keys as you play.

As a result, players have to coordinate complex movements with perfect timing to play the notes they intend, all without seeing what they’re doing. 

Treble Buttons

Button accordions don’t feature a keyboard with keys.

Instead, they have a complex series of treble buttons arranged in a particular order on the player’s right side.

Accordion makers introduced treble buttons to increase the instrument’s scope of sound, and most button accordions have more treble controls than the average keyboard accordion. 

Unlike a keyboard accordion, which might feature between 25 and 45 treble keys, the button accordion usually has around 41 treble buttons. 

Many players believe button accordions to be more complex, and as a result, the superior instrument.

Why not give both a try and decide for yourself!

Bass Buttons

Both types of accordions have bass buttons in addition to either keys or treble buttons.

While the treble button might number up to 45 or more, there are usually around 120 bass buttons on the average accordion.

Most bass buttons lie outside the player’s field of vision.

In addition to fingering treble notes and moving the bellows, they have to memorize each and every position of each bass button.

Impressive, to say the least!

Stradella System

Accordion makers have different preferences on bass button setups for their instruments.

Most use what is known as the Stradella System.

Makers arrange the bass buttons in circles of fifths along columns on the left side of the instrument, marking key buttons with rhinestones as landmarks. 

Freebass System

Other accordion makers might use what is known as the free bass system, in which each chromatically-arranged button corresponds to a single note.

This version is more popular in Europe, but you can still find them in the Americas if you look hard enough. 

Air Button

In piano and button accordions, you’ll typically find what is known as an air button.

This part allows the player to move the bellows without making a sound, which is useful for transitioning between parts in a composition or returning to the resting position after finishing. 


An accordion’s reeds emit the sound coming to the air pushed out by the bellows.

They’re typically steel or brass, while the valves are made of a softer material like leather.

You can find reeds positioned in a series of reed blocks inside the casings on either side of the instrument.

The reeds in both the treble casing and bass casing are all the same material and structure.

However, their positions vary depending on valve location and button position. 

Having reeds able to play both treble and bass notes means accordion players are some of the most versatile musicians out there.

They can play chords and melody simultaneously, essentially making them a one-man band!


In addition to the plethora of other ways an accordion player can modify their sound, the switches allow them to change the instrument’s timbre and sound quality. 

A standard accordion typically has two switches.

One on the treble side, and another on the bass, both connected to the reed blocks inside the casings.

Using the switches, the player can shift the position of the reed blocks into another octave.

This allows them to play different octaves simultaneously. 

With switches, skillfully coordinated with keystrokes, button presses, and bellows movements, a player can go through a wide range of sounds simply impossible for other instruments. 

The Bellows

The bellows is the largest and most recognizable part of the accordion to many, connecting the instrument’s treble and bass sides.

It operates when the player pulls both sides of the instrument apart, sucking air into the bellows’ interior.

Then, the player pushes inward, and air then escapes through the reeds. 

As air passes into and out of the bellows, the player fingers the treble and bass buttons, opening valves to the various reeds that make different notes.

The player has to depress the air button when pulling and pushing the bellows if they don’t want to make a sound. 

The materials that accordion makers use to construct the bellows vary depending on how expensive the instrument is and what embellishment they want.

However, bellows are usually made of durable cardboard and cloth supported and protected by leather and metal. 

Wrapping Up our Guide to the Accordion’s Parts

There you have it! All the parts of an accordion.

If you ever want to learn the accordion, then it’s important to get a handle on the various bit and pieces that make up the instrument.

Not knowing the difference between treble and bass buttons might spell trouble! 

Also, check out our list of famous accordion players for some more inspiration for your music!

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Dan Farrant, the founder of Hello Music Theory, has been teaching music for over 15 years, helping hundreds of thousands of students unlock the joy of music. He graduated from The Royal Academy of Music in 2012 and then launched Hello Music Theory in 2014. He plays the guitar, piano, bass guitar and double bass and loves teaching music theory.