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Toolvica

Note Frequency Calculator

Find the frequency of any musical note in Hz across octaves with A4 reference.

Hz

Frequency

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MIDI

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Period

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Wavelength

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NoteHzMIDI

Click any row to select · Full 0–8 (108 notes) · A0 27.5 Hz — C8 4186 Hz

Open in Tone Generator →

What this Note Frequency Calculator offers

Bidirectional note ↔ Hz with piano keyboard, full 108-note table (C0–B8), adjustable A4 415–466 Hz and cents detune. Results include MIDI, period and wavelength.

  • Equal-temperament math with A4 415 to 466, detune −50…+50 cents, #/b toggle
  • MIDI number, period in ms and wavelength in meters + Hz → nearest note with cents
  • Full 108-note table (0–8) + piano keyboard, click any row/key to select
  • Sine preview, Hz copy, shareable link (?note=&a4=) and tone generator handoff

How to use

  1. Pick note C–B and octave 0–8 via selects, piano keys, or table rows. Toggle #/b for enharmonic display.
  2. Set A4 415–466 Hz (presets 415 Baroque/432/440/442) and detune −50…+50 cents; or type Hz in Frequency → Note to reverse-lookup nearest note + cents.
  3. Read frequency Hz with MIDI, period and wavelength. Full 108-note table highlights current note; piano shows active key.
  4. Play sine preview, copy Hz, copy shareable link (?note=&a4=), or send to Tone Generator. Works offline, private.

What is note frequency?

Every musical note vibrates at a fixed frequency in equal temperament. A4 at 440 Hz is the anchor, and each semitone multiplies by the twelfth root of two.

Frequency equals A4 times two to the power of semitone distance divided by twelve. Middle C (C4) is about 261.63 Hz, one octave up doubles to 523.25 Hz.

At 440 Hz the wavelength in air is about 78 cm, which is why bass notes feel big and need large speakers while high notes beam from small tweeters.

Features

Exact & reverse

Note → Hz and Hz → nearest note (with MIDI + cents). Custom A4 415–466 Hz and detune for sound design, 432/440/442 presets.

Full 108-note table + piano

All notes C0–B8 (108) with Hz and MIDI, plus piano keyboard. Click any row or key to select. #/b enharmonic toggle included.

Hear, copy & share

Play clean sine, copy Hz, copy shareable link (?note=&a4=) and send to Tone Generator.

Piano & tuner link

Piano keyboard for current octave + #/b toggle. Send frequency to Tone Generator or check against Tuner.

Tips

Match your ensemble

Set A4 to 442 or 443 for orchestras, 415 for baroque, before reading values.

Detune for width

Copy plus and minus few-cents values to layer detuned oscillators.

Check by ear

Play the note here, then compare with your instrument through the tuner.

FAQ

What is the frequency of A4?
440 Hz by ISO standard. Orchestras often use 442 to 443, baroque ensembles 415. Change A4 here and every note recalculates.
What is the formula?
Frequency equals A4 times two to the power of MIDI minus 69 divided by twelve. For C4 with MIDI 60 at A4 440, that is about 261.63 Hz.
What are MIDI numbers?
MIDI numbers label every semitone from 0 to 127. Middle C is 60, A4 is 69. The tool shows the number for each note so you can program synths and DAWs directly.
Why does my synth sound out of tune?
Check A4 reference first, then detune cents. A 10-cent drift is clearly audible against other instruments.
What is wavelength used for?
Wavelength is sound speed divided by frequency, about 343 meters per second in air. It guides speaker placement and room treatment for low notes.
Can I hear the note?
Yes. Play renders a clean sine at your exact frequency with detune applied, so you can compare directly with your instrument.

References

1. Twelve-tone equal temperament with A4 reference pitch.

2. Web Audio API — MDN. developer.mozilla.org/Web/API/Web_Audio_API

For practice and education. Timing accuracy depends on device performance and browser audio scheduling. For critical recording, compare with a hardware metronome.