Middle C (C4)

Central reference pitch of the keyboard, sounding at about 261.63 Hz in A440 equal temperament.

Core Principles & Analysis

• Notated on the ledger line between the treble and bass staves of the grand staff.
• Designated C4 in scientific pitch notation, the fourth C on a standard 88-key piano.
• The obsolete 'scientific pitch' standard set it to exactly 256 Hz, a power of two.

Specifications & Metrics

• FREQUENCY: 261.63 Hz