How Piano Pedals Work

Pianote  /  Technique  /  UPDATED Feb 9, 2024

What do the pedals on a piano do? Pedals are foot controllers that alter the piano’s sound, allowing you to shape the character and tone of your playing and allowing more room for artistic expression. Pedals are powerful tools—tools you’ll definitely want to master as a pianist!

In this post, we’ll introduce you to the three standard grand piano pedals: the sustain, the sostenuto, and the una corda. We’ll also share some tips on how to use pedals effectively in your favorite songs.

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What do the pedals on a piano do?

The three pedals on a standard grand piano are, from right to left: the sustain pedal (also called the damper pedal), the sostenuto, and the una corda. (Upright pianos typically have a practice pedal in place of the middle sostenuto pedal.) The sustain and sostenuto pedals sustain sound by allowing strings to resonate freely. Meanwhile, the una corda changes the tone and volume of your playing.

What do the pedals on a piano do? Three grand piano pedals labelled (from left to right) una corda, sostenuto, damper/sustain.

The Sustain Pedal

To understand how the sustain pedal works, let’s review how strings on a piano work. When you press a piano key, you activate a felt part called a damper and lift it away from the key’s piano string. This allows the string to vibrate freely when a hammer hits it.

When you let off the piano key, the damper comes back down. This stops the string from vibrating, muting it.

So what happens when you press the damper pedal with your foot? When you pedal, all the dampers in the piano lift for as long as your foot is on the pedal. The piano’s strings can now resonate freely until they naturally stop. (Here’s an animated demonstration of how this works.)

The sustain pedal is popular in all styles of music and is responsible for the piano’s iconic rich sound. It can instantly level up your playing, so it’s definitely worth practicing damper pedal techniques!

How do pianos work? Knowing the basic mechanics behind an acoustic piano can help you understand your instrument and play better. Here’s a comprehensive breakdown of a piano’s inner workings. Pianos are beautiful machines!

The Sostenuto Pedal

Not to be confused with the sustain pedal, the middle pedal of a grand piano is called the sostenuto. You can think of the sostenuto pedal as a selective sustain pedal because it sustains a specific note or group of notes rather than the entire keyboard.

When you press a key and then press the sostenuto pedal, a bar inside the piano will “hook” the damper away from the key’s strings. As long as the sostenuto is depressed, that key’s strings will resonate.

Sostenuto pedaling is relatively rare. This technique is typically only found in later classical pieces of the modern era. Sometimes, the sostenuto is used to sustain a low bass note so that both hands can be used to play unsustained notes in the treble.

The Una Corda

Did you know that most piano hammers (other than the lower bass notes) hit three strings, not just one?

“Una corda” means “one string.” Pressing the una corda pedal on a grand piano shifts the keyboard to the right, making keys hit one string instead of three. This creates a softer, muted tone that gives the piano a mellow charm. The una corda is especially popular in “impressionist” pieces like those by Debussy and Ravel.

The una corda works slightly differently on an upright piano. In an upright piano, the una corda causes the hammers to move closer to the strings so that they don’t strike the strings as hard.

The Una Corda Piano: If you like the sound of the una corda pedal, you may be delighted to know that there’s a piano made up entirely of keys with one string per note!

Other Pedals

In upright pianos, the middle pedal is often a practice pedal. This pedal causes a piece of cloth to slide between the hammers and the strings, muting sound and allowing students to practice late into the night without bothering neighbors and housemates.

Some pianos have a bass pedal that sustains only the bass keys.

Pedaling Tips

Pedals can be an incredible tool for piano players, but it’s important to keep a few things in mind:

  • Learn proper pedaling technique. Anchor your heel to the ground and press the pedal with the ball of your foot. This position gives you the most control.
  • Pay attention to pedal phrasing. In sheet music, little peaks are used to indicate when to “clear” the pedal. When you see a peak, quickly raise the pedal about halfway up before pressing it back down. This will clear the muddiness of the phrase.
4 measures of sheet music with pedaling markings and instructions.
  • Do not over-pedal! Use your sustain pedal sparingly. Using it too much or keeping it pressed down without a break will muddy the sound. Experienced piano players make the pedal count by using it only when it’s most needed.
  • Learn to play legato without the pedal. It’s tempting to use the sustain pedal as an easy way to connect your notes (legato), but it really shouldn’t be used this way. Pedaling should be treated as an ornament, not a constant.

My rule of thumb when using the sustain pedal is to lift it each time there is a chord change or a change in harmony. If you don’t know how to tell if there has been a change in harmony, go with your instincts. Your ear will be able to tell you if your sound has become muddy and you need to release the pedal.

Lisa Witt, Coach and Content Director at Pianote

We hope this article helps answer the question, “What do the pedals on a piano do?” and inspires you to play and pedal! (Just don’t pedal too much 😉 )

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Charmaine Li is a Vancouver writer who has played piano for over 20 years. She holds an Associate diploma (ARCT) from the Royal Conservatory of Music and loves writing about the ways in which music—and music learning—affects the human experience. Charmaine manages The Note. Learn more about Charmaine here.

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