A Guide to Sustain Pedal

A sustain pedal is the foot-operated control that allows a piano or keyboard player to sustain notes beyond the point at which the key is released. On an acoustic piano it is the rightmost of the three pedals and is operated by the right foot; on electronic keyboards and digital pianos it is typically a separate accessory that plugs into a dedicated socket. It is one of the most frequently used controls in piano playing and is essential for a wide range of musical styles.

How It Works

On an acoustic grand or upright piano, pressing it lifts the dampers from the strings. Dampers are felt pads that rest against the strings when not in use, stopping the string from vibrating when the key returns to rest. With the dampers lifted, every string that has been struck continues to vibrate until the pedal is released or the vibration decays naturally. This allows notes and chords to ring beyond what the fingers alone can sustain, creates a blended harmonic texture, and adds resonance to the overall sound.

Electronic Keyboards and Digital Pianos

Electronic instruments replicate this function through a signal sent to the instrument's sound engine. A basic sustain pedal sends a simple on/off signal: the instrument continues to apply sustain while the pedal is depressed and cuts it when released. More sophisticated instruments and pedals support half-pedalling, which replicates the nuanced partial pedal technique used on acoustic instruments. The socket type varies by manufacturer; most instruments use a standard 6.35mm mono jack.

Polarity and Compatibility

A common issue when connecting a third-party pedal to an electronic instrument is reversed polarity: the instrument sustains when the pedal is released rather than pressed. Most modern instruments auto-detect polarity on startup, but some require the pedal to be unplugged while the instrument is powered on to set the correct behaviour. Checking the instrument manual before purchasing a third-party pedal avoids this problem.

Types of Sustain Pedal

The simplest form is a small plastic switch-style pedal, adequate for basic practice. Semi-weighted and spring-loaded variants provide more resistance and a feel closer to an acoustic piano pedal. Full-size piano-style pedals, sometimes called damper pedal boards, use a lever mechanism that closely mimics an acoustic instrument. These are preferred by pianists who practise on electronic instruments but also play acoustic pianos.

Musical Use

The sustain pedal fundamentally changes the texture and resonance of keyboard playing. In classical repertoire, pedal markings are often written into the score. In popular, jazz and contemporary music, its use is typically at the player's discretion. Learning to time the pedal with harmonic changes rather than holding it continuously is one of the core technical skills in piano playing. Poor pedal technique — holding the pedal across harmonic changes — produces muddy, indistinct sound; good technique enhances clarity and warmth simultaneously.

For purchasing advice, see the buyer's guide to sustain pedals. For beginners, see the beginner's guide.

Frequently Asked Questions