C4
262 Hz
🔊 VOL
🎹 Piano Theory Guide

Learn Piano
Smarter

A fully interactive guide to piano octaves, the musical staff, note durations, rhythm and the metronome — all in one page.

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88 Keys Explained C0 → C7 Octaves Treble & Bass Clef Interactive Metronome Beats & Bars

What Is an Octave?

The word octave comes from Latin octava — "eighth." It describes the interval between a note and another with exactly double its frequency. On a piano it spans 8 white keys, from one C to the very next C.

12
Semitones in every octave
×2
Frequency multiplier per octave
440 Hz
Concert A (A4) — tuning reference
262 Hz
Middle C (C4) — universal anchor
Why does frequency double? The ear hears pitch logarithmically — two notes an octave apart sound like the "same" note in different registers. Double the vibrations per second = one octave up.

Why C0 to C7?

Scientific Pitch Notation (SPN) assigns a number to each octave starting from 0. C starts each octave — it falls just after every pair of black keys. Click any card to highlight that octave on the keyboard below.

Click or hover any key to explore
🎹 Hover or click any key · Keyboard: A–L plays C4–D5

Notes on the Staff

Treble Clef (G Clef)
Range: C4 → G6

The curl wraps around the G4 line. Used for higher notes — right hand piano, violin, flute.

Lines (↑): E4 · G4 · B4 · D5 · F5
Spaces (↑): F4 · A4 · C5 · E5

Bass Clef (F Clef)
Range: E2 → C4

The two dots flank the F3 line. Used for lower notes — left hand piano, cello, bass.

Lines (↑): G2 · B2 · D3 · F3 · A3
Spaces (↑): A2 · C3 · E3 · G3

★ Middle C (C4) sits on a ledger line between the two staves — below treble, above bass. It is the anchor of the grand staff.

Staff ↔ Keyboard Correlation

Every step up a line or space on the staff = the next white key to the right on the piano. Higher on the staff = further right on the keyboard.

NoteOctaveStaff PositionFrequencyClef

Every Key on the Staff

Click any of the 88 keys below to see exactly where it sits on the grand staff — whether it's a ledger line below bass, inside treble, or far above in the upper octaves. The staff updates in real time.

Click a key to begin
Note Name
Octave
Staff Position
Clef
Highlight Octave
Try clicking the C keys to see Middle C sit between the two staves.

Beat, Rhythm & Note Duration

Pitch tells you which key to press. Rhythm tells you how long to hold it. A beat is the steady pulse — like a heartbeat. A note's duration tells you how many beats to hold that note.

The Four Basic Note Values — in 4/4 time, one bar = 4 beats

How They Fill a Bar — click a row to animate

Whole   Half   Quarter   Quaver (8th)

The Metronome

A metronome marks exact tempo in BPM (beats per minute). At 60 BPM, one beat = one second. At 120 BPM, one beat = half a second. Each tick = one beat.

60
BPM

Hold Duration at Current Tempo

NoteBeatsDuration at 60 BPMRelative Length
Whole 𝅝4 beats4.00 s
Half 𝅗𝅥2 beats2.00 s
Quarter ♩1 beat1.00 s
Quaver ♪½ beat0.50 s
Rule: Duration (s) = (beats ÷ BPM) × 60. At 60 BPM a quarter note = 1 s. At 120 BPM it's 0.5 s.
🎵 Play a note with the metronome

Bars, Measures & Time Signatures

Music is divided into equal chunks called bars (or measures). A time signature tells you how many beats per bar and which note value counts as one beat.

Reading a Time Signature
4
4
Four-Four Time
Top (4): 4 beats per bar
Bottom (4): quarter note = 1 beat

The top number is your count. The bottom number is the reference note — 4 = quarter note, 2 = half note, 8 = eighth note.

Common Time Signatures

4
4
4/4 — Common Time
4 quarter-note beats per bar. The most common time in pop, rock, and classical.
3
4
3/4 — Waltz Time
3 beats per bar. ONE-two-three. Used in waltzes and minuets.
2
4
2/4 — March Time
2 beats per bar. ONE-two. The strong marching left-right feel.
6
8
6/8 — Compound Duple
6 eighth-note beats, felt in 2 pulses. Lilting flow — jigs, barcarolles.

Counting Beats Inside a Bar — Interactive

A 4/4 bar always contains exactly 4 beats. Choose a note pattern, press Play — the metronome ticks on each beat while the playhead shows exactly where you are.

TEMPO 72 BPM
COUNT
Why 4 Beats? The Rule of the Bar
1
STRONG
Downbeat
2
weak
Unaccented
3
medium
Secondary
4
weak
→ leads to 1
Rhythm = Duration Pattern

Fill a 4/4 bar with any combination totalling 4 beats: ♩ + 𝅗𝅥 + ♩ = 4

Beat = Steady Pulse

The metronome keeps the beat constant. Notes land on or between beats — the pulse never stops.

Key Takeaways

1
Octaves double frequency

A4 = 440 Hz → A5 = 880 Hz → A3 = 220 Hz. The relationship is perfectly logarithmic.

2
C0–C7 is Scientific Pitch Notation

The number tells you which octave. C starts each octave — after every pair of black keys.

3
C4 is the universal anchor

Middle C (~262 Hz) sits at the centre of the piano and on a ledger line between the two staves.

4
Staff position = pitch height

Higher on the staff = higher pitch = further right on the keyboard. All three are equivalent.

5
Two clefs cover the full range

Treble covers C4–G6, Bass covers E2–C4. Together they form the Grand Staff used for piano.

6
Notes have duration, not just pitch

Whole = 4 beats · Half = 2 · Quarter = 1 · Quaver = ½. Rhythm is how these combine in time.

7
A bar = 4 beats in 4/4 time

Barlines divide music into equal chunks. In 4/4: STRONG · weak · medium · weak.

🎹
Pitch + Rhythm = Music

Which key, how long, when, and how fast — the four dimensions of music.

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