A standard piano has 88 keys — 52 white and 36 black — spanning just under eight octaves, from A0 to C8. Here's everything you need to know about how those keys are named, numbered, and mapped to written music.
The interactive keyboard below shows all 88 keys of a standard piano, from A0 (the lowest note) to C8 (the highest). Every white key is labeled. The C notes are highlighted in pink — notice how they divide the keyboard into repeating groups. Middle C (C4) is marked in red.
Western music uses only seven letter names: A, B, C, D, E, F, G. After G, the sequence starts again from A. These seven letters label all the white keys on a piano — repeat the pattern across every octave and you've named all 52 of them.
Black keys represent the sharps and flats — the notes between the natural notes. A sharp (♯) raises a note by a half step; a flat (♭) lowers it. Black keys appear in a distinctive pattern of groups of two and three, which makes every note easy to find without looking at labels.
Each group of 12 notes (7 white + 5 black) is called an octave. To distinguish notes with the same letter name, musicians add an octave number: C4 is one octave above C3 and one octave below C5. The system is called Scientific Pitch Notation.
Octave numbers change at each C — so the sequence runs: …A3, B3, C4, D4, E4… The piano spans from A0 (the lowest key) to C8 (the highest key).
| Octave | Range | Keys | Notable pitch |
|---|---|---|---|
| 0 | A0 – B0 | 3 | A0 — lowest piano key |
| 1 | C1 – B1 | 12 | — |
| 2 | C2 – B2 | 12 | — |
| 3 | C3 – B3 | 12 | — |
| 4 | C4 – B4 | 12 | C4 = Middle C · A4 = 440 Hz |
| 5 | C5 – B5 | 12 | — |
| 6 | C6 – B6 | 12 | — |
| 7 | C7 – B7 | 12 | — |
| 8 | C8 | 1 | C8 — highest piano key |
Middle C (C4) is the most important landmark on the piano. It sits at the physical center of the keyboard and at the intersection of the treble and bass clefs on the grand staff — written on a ledger line between the two staves.
Middle C is easy to find: it's the first C to the left of the group of two black keys nearest the center of the keyboard. Singers, conductors, and arrangers use it as a universal reference point — it sits within the natural singing range of most voices.
Concert pitch A4 — one octave and a sixth above Middle C — is tuned to exactly 440 Hz, the international standard since 1939. Most orchestras, digital tuners, and synthesizers default to this frequency.
Piano music is written on a grand staff: two five-line staves joined by a brace. The upper staff uses the treble clef (right hand); the lower uses the bass clef (left hand). Middle C sits on a ledger line between them.
Lines bottom→top: E4, G4, B4, D5, F5
Spaces bottom→top: F4, A4, C5, E5
Range extends further with ledger lines
Lines bottom→top: G2, B2, D3, F3, A3
Spaces bottom→top: A2, C3, E3, G3
Range extends further with ledger lines
Notes beyond the staff range use ledger lines — short lines added above or below the staff. Middle C always sits on the first ledger line below the treble staff (and the first above the bass staff).
The piano's key count evolved over 200 years. Bartolomeo Cristofori's first pianoforte (~1700) had just 54 keys. As composers pushed for wider ranges and builders improved their craft, keyboards expanded.
Steinway settled on 88 keys in the 1880s and nearly every major manufacturer followed. The limits are acoustic: strings above C8 are too short to sustain a musical tone, and strings below A0 would need to be impractically long. A handful of specialty instruments (like the Bösendorfer Imperial) extend the bass range to 97 keys — but 88 remains the worldwide standard.
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