How does a piano work?

A piano is a string instrument played with hammers. Each of its 88 keys throws a felt hammer at one, two or three steel strings. About 230 strings pull with nearly 20 tonnes in total, so they are stretched across a cast-iron plate, above a thin spruce soundboard.

Read how it works: How does a piano work? · The history of the piano · More boxes on Glassbox

Chapters in this interactive model

1. Inside a grand piano: Keys, hammers, dampers, strings, an iron frame and a big wooden board.
2. From key to hammer: A chain of levers throws the hammer, then lets it go.
3. What sets a string’s note: Length, tension and weight: Mersenne’s three laws.
4. Why a piano is loud: A thin string can’t push air. A big wooden board can.
5. Eighty-eight keys, twelve to an octave: From 27.5 Hz to 4,186 Hz, each key 6% higher than the last.
6. Soft, loud, and the three pedals: Hit harder for louder and brighter. The pedals do the rest.