What formula calculates note frequency?

Equal temperament uses f = A4 × 2^((n − 69) / 12), where n is the MIDI note number (C-1 = 0, middle C4 = 60, A4 = 69) and A4 is the chosen reference pitch (440 Hz by default).

What is a MIDI note number?

MIDI assigns an integer 0–127 to each pitch. C-1 = 0, C0 = 12, C4 (middle C) = 60, A4 = 69, and B8 = 119. The number increments by 1 for each semitone up.

How is wavelength in air calculated?

Wavelength equals the speed of sound in air (343 m/s at approximately 20 °C) divided by frequency: λ = 343 / f. Higher notes have shorter wavelengths.

What does period mean in this context?

Period is the time for one complete sound-wave cycle: T = 1 / f, expressed in milliseconds. A4 at 440 Hz has a period of about 2.273 ms.

What is the difference between 440 Hz and 432 Hz tuning?

A4 = 440 Hz is the ISO 16 international standard. A4 = 432 Hz is an alternative preferred by some musicians. The gap is approximately 31 cents — roughly a third of a semitone.

Why does the chromatic table cover only one octave?

Each octave doubles every frequency. The selected octave table gives you all 12 notes (C through B) at a glance so you can compare semitone relationships without scrolling through all 88+ pitches.

Note To Frequency Detailed

Name: Note To Frequency Detailed
Availability: InStock
Author: Nham Vu

Select any note (C0–B8), choose a tuning reference, and instantly get frequency, MIDI number, wavelength, period, and a full chromatic table for the octave.

Note Settings

Note Name

Octave

Tuning Reference (A4)

Select a note and click Convert

Chromatic Scale — All 12 Notes in Octave 4

Note	MIDI	Frequency (Hz)	Period (ms)	Wavelength (m)

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Summary

Select any note (C0–B8), choose a tuning reference, and instantly get frequency, MIDI number, wavelength, period, and a full chromatic table for the octave.

How it works

Select a note name (C through B) from the first dropdown.
Choose the octave (0 through 8) from the second dropdown.
Pick a tuning reference — A4 = 440 Hz is the modern concert standard.
Click Convert to see the frequency in Hz, MIDI number, wavelength in air, and period.
The chromatic reference table below shows all 12 notes in the selected octave with their Hz values.
Click Play to hear a 1-second sine tone at the calculated frequency.

Use cases

Verify tuning accuracy by checking exact Hz values for any chromatic note.
Find MIDI note numbers for synthesizer and DAW programming.
Calculate wavelengths for acoustic room treatment design.
Compare all 12 semitones in an octave at a glance with the chromatic table.
Explore alternate tuning standards such as 432 Hz or 415 Hz Baroque pitch.
Teach equal temperament math and octave frequency relationships.
Cross-reference note names, MIDI numbers, and Hz in one view.
Generate precise sine tones for hearing tests and audio calibration.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu