What does A4=440Hz mean?

A4=440Hz is the international standard tuning reference, meaning the A above middle C vibrates at 440 Hz. Established in 1939, it is the global standard for musical tuning used by most instruments and music production.

How is note frequency calculated?

Note frequencies follow a geometric progression. Each octave (12 semitones) doubles the frequency. Formula: f = 440 × 2^(n/12), where n is the number of semitones from A4. For example, C5 is 3 semitones above A4, so f = 440×2^(3/12) ≈ 523.25Hz.

What note naming systems are supported?

Three systems: 1) Scientific pitch notation (e.g., C4, A4) — recommended; 2) Helmholtz notation (e.g., c', a'); 3) MIDI note numbers (0-127). C4 = MIDI 60 = middle C.

Why use tunings other than 440Hz?

While 440Hz is standard, some orchestras use 441Hz, 442Hz, or 443Hz for a brighter sound. Baroque music often uses 415Hz, and Classical period music uses 430Hz. This calculator supports custom reference frequencies.

🎵 Note Frequency Calculator

Find the frequency (Hz) of any musical note. Supports A4=440Hz standard and custom tuning. Includes 88-key piano with audio playback.

🎹 Note Lookup

Note

Octave

A4 Reference (Hz)

🎼 Piano Keyboard (click to play)

📋 Full 88-Key Frequency Table

Note	Octave	Frequency (Hz)	MIDI	Actions

What is Note Frequency Calculator - Pitch to Hz, 88 KeysBase?

Note Frequency Calculator - Pitch to Hz, 88 KeysBase is a free online tool that runs entirely in your browser. No download or signup needed — enter Note and Octave to get results instantly. All data is processed locally.

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