A sustain pedal is the rightmost pedal on a piano that lifts all the dampers off the strings at once, allowing notes to ring out after you release the keys. It’s the most frequently used of the piano’s pedals and the one that gives piano music its characteristic flowing, connected sound.
How It Works on an Acoustic Piano
Every key on an acoustic piano has a small felt pad called a damper resting against its strings. When you press a key, that individual damper lifts so the strings can vibrate and produce sound. The moment you let go, the damper drops back down and silences the note. This is why staccato playing sounds so crisp: each note cuts off the instant your finger leaves the key.
When you press the sustain pedal, a mechanical linkage lifts every damper in the piano simultaneously. Now any note you play keeps ringing even after you release the key, because there’s nothing pressing against the strings to stop the vibration. The effect goes beyond simple sustain, though. With all the dampers raised, every undamped string becomes a sympathetic string. When you strike one note, strings tuned to related frequencies vibrate slightly on their own, creating a richer, more resonant tone than you’d get from a single key press alone. This sympathetic resonance is a big part of what makes a grand piano sound so full and warm during sustained passages.
Where It Sits Among the Other Pedals
A standard acoustic piano has three pedals. The sustain pedal (also called the damper pedal) sits on the far right, where your right foot naturally rests. The left pedal is the soft pedal, which shifts the hammers to reduce volume. The middle pedal varies by instrument: on most grand pianos it’s a sostenuto pedal that sustains only the notes you’re already holding when you press it, while on many upright pianos it’s a practice mute that dramatically quiets the entire instrument.
Of the three, the sustain pedal sees the most use by far. Many beginner keyboards ship with only a single pedal input, and it’s always for sustain.
Reading Pedal Markings in Sheet Music
Sheet music uses two standard markings for the sustain pedal. “Ped.” written below the staff tells you to press the pedal down. A flower-shaped asterisk symbol (✱) tells you to release it. These markings appear underneath the bass clef staff, aligned with the beat where your foot should move. Some modern editions replace these with a horizontal bracket line: the pedal goes down where the bracket starts and comes up where it ends, which makes the timing easier to read at a glance.
Half-Pedaling
The sustain pedal isn’t strictly an on/off switch on an acoustic piano. You can press it partway down, a technique called half-pedaling, to partially lift the dampers. This lets some vibration continue while still allowing the dampers to lightly touch the strings and absorb lower frequencies. The result is sustain without the muddiness that comes from letting bass notes pile up unchecked.
Half-pedaling is especially useful in passages where you want a melody to sing clearly over a moving left hand. By keeping the pedal at a shallow depth, you can sustain the higher melody notes while the lower accompaniment stays relatively clean. The exact feel varies from piano to piano, since no two instruments have identical pedal mechanisms, spring tension, or damper clearance. Pianists who perform on unfamiliar instruments typically spend a few minutes testing the pedal’s response before playing.
Sustain Pedals for Digital Keyboards
Digital keyboards and synthesizers don’t have dampers or strings, so the sustain pedal works as an electronic controller instead. Most sustain pedals for keyboards are simple foot switches: press down to send an “on” signal, release to send “off.” In the MIDI standard that keyboards use to communicate, sustain is assigned to controller number 64 (CC 64). A value of 64 or higher means the pedal is engaged, and anything below 64 means it’s off.
Budget pedals typically operate as a binary switch, giving you only fully on or fully off. Higher-end continuous pedals can send a range of values, which allows half-pedaling on digital pianos designed to interpret that data. Your keyboard needs to support half-pedal input for this to work; otherwise, even a continuous pedal will behave like a simple switch. If you’re shopping for a sustain pedal for a keyboard, check the polarity as well. Some brands default to “normally open” and others to “normally closed,” and getting it backwards will reverse the pedal’s behavior so that notes sustain when your foot is off and cut out when you press down. Many keyboards auto-detect polarity at startup, but not all do.
Why It Matters Musically
Without the sustain pedal, piano music would sound strikingly different. Legato passages, where notes flow smoothly into one another, would require you to physically hold every key for its full duration. Chords spanning more than an octave would be impossible to sustain, since your hand would need to leave one set of keys to reach the next. The pedal solves both problems by letting sound persist independently of your fingers.
It also shapes the instrument’s tone. The sympathetic resonance created when all dampers are raised adds depth and complexity that simply holding keys down can’t replicate. Composers from Beethoven onward wrote specifically for this effect, and most classical, jazz, and pop piano music assumes the player is actively managing the sustain pedal throughout. Learning when to press and release it, often called “pedal changes,” is one of the core skills that separates fluid, musical playing from something that sounds choppy or blurred.