How do you convert frequency to musical note?

To convert a frequency (Hz) to a musical note, calculate the MIDI note number using the formula: MIDI = 69 + 12 × log2(frequency / 440). The integer part maps to a note name (C, C#, D, ... B) and octave, while the fractional part gives the cents offset. For example, 440 Hz = MIDI 69 = A4 with 0 cents. 261.63 Hz = MIDI 60 = C4 with 0 cents.

What is the frequency of A4?

A4 = 440 Hz in standard concert pitch (ISO 16:1975). Some orchestras use 442 Hz for a brighter sound, and some musicians prefer 432 Hz (sometimes called 'Verdi tuning'). This converter supports all three reference frequencies plus any custom value between 400 and 460 Hz.

What are cents in music?

A cent is 1/100 of a semitone (half step). There are 100 cents between any two adjacent notes (e.g., C4 and C#4). Cents measure how far a frequency is from the nearest standard note. A reading of +5 cents means the frequency is 5 cents sharp of the nearest note; −3 cents means 3 cents flat. Most humans cannot hear pitch differences smaller than about 5–10 cents.

What is the formula to convert a note to frequency?

The formula is: frequency = A4 × 2^((MIDI_note − 69) / 12), where A4 is the reference frequency (440 Hz by default) and MIDI_note is the note's MIDI number (A4 = 69, C4 = 60, etc.). For example, C5 = 440 × 2^((72−69)/12) = 440 × 2^0.25 ≈ 523.25 Hz.

Why is my frequency showing a cents offset?

Most real-world frequencies do not land exactly on a standard equal-tempered note. For example, 445 Hz is close to A4 (440 Hz) but about 19 cents sharp. The cents offset tells you how far the input frequency deviates from the nearest standard note, which is useful for tuning accuracy and acoustic analysis.

What is the difference between 432 Hz, 440 Hz, and 442 Hz tuning?

440 Hz is the international standard concert pitch (ISO 16) used by most musicians and orchestras since 1955. 442 Hz is commonly used by European orchestras for a slightly brighter tone. 432 Hz is an alternative tuning popular in some online communities; there is no scientific evidence for audio quality advantages, but some musicians prefer its lower, warmer sound.

Frequency to Note Converter

Convert any frequency in Hz to the nearest musical note with cents offset, or find the exact frequency of any note. Supports A4 = 432, 440, or 442 Hz — free, browser-based, no download.

A4 reference:

Use flats (♭)

→ Frequency to Note

Enter frequency (Hz)

NoteA4

Cents offset0¢

Nearest exact freq440.00 Hz

MIDI note69

← Note to Frequency

Select note

Octave

Frequency440.00Hz

MIDI note69

How to Use the Converter

Hz → Note: Enter a frequency in Hz (e.g., 440) to see the nearest note, octave, and cents offset.
Note → Hz: Click a note name and octave to see its exact frequency.
Change the A4 reference (432 / 440 / 442 Hz) if your instrument uses non-standard tuning.
Toggle flats (♭) if you prefer Db over C#, Bb over A#, etc.
Use the quick buttons for common reference frequencies and notes.

The Conversion Formula

The relationship between frequency and musical notes is based on the equal-tempered scale, where each octave is divided into 12 equal semitones. Given a reference frequency for A4 (standard: 440 Hz), any note's frequency can be calculated:

f = A₄ × 2^{(n − 69) / 12}

where n is the MIDI note number (A4 = 69) and A₄ = 440 Hz

To go the other direction — frequency to note — invert the formula:

n = 69 + 12 × log₂(f / A₄)

The integer part of n gives the nearest MIDI note (which maps to a note name and octave), and the fractional part multiplied by 100 gives the cents offset — how far the frequency is from the exact note.

Note Frequency Reference Table

Standard equal-tempered frequencies for common musical notes (A4 = 440 Hz). Use this as a quick lookup for instrument tuning and audio calibration.

Note	Frequency	MIDI	Common Use
C0	16.35 Hz	0	Lowest audible piano-style note
A0	27.50 Hz	21	Lowest key on a standard 88-key piano
E1	41.20 Hz	28	Lowest note on a 4-string bass (B0 on 5-string)
E2	82.41 Hz	40	Low E string — guitar (standard tuning)
A2	110.00 Hz	45	A string — guitar
C3	130.81 Hz	48	Low C — cello C-string
G3	196.00 Hz	55	G string — guitar / violin G-string
C4	261.63 Hz	60	Middle C — piano center
A4	440.00 Hz	69	Concert pitch reference (ISO 16)
C5	523.25 Hz	72	C one octave above middle C
A5	880.00 Hz	81	A one octave above A4
C8	4186.01 Hz	108	Highest key on a standard piano

What Is a Frequency-to-Note Converter Used For?

Instrument tuning

If you know the target frequency of a string or key, convert it to a note name to verify your tuner is showing the right pitch — especially useful for alternate tunings.

Audio engineering

Identify which musical note corresponds to a resonant frequency, hum, or whine in a recording. Common power-line hum at 50/60 Hz is near G1 (49 Hz) / B1 (62 Hz).

Acoustics education

Demonstrate the logarithmic relationship between frequency and pitch. Students can explore why each octave doubles the frequency (e.g., A4 = 440, A5 = 880).

Hearing tests

Convert audiometric test frequencies (250, 500, 1000, 2000, 4000, 8000 Hz) to musical notes to understand what pitches audiologists are checking.

Microtonal music

Composers working in non-standard tunings (just intonation, 31-EDO, etc.) can use the cents offset to quantify how far a frequency deviates from equal temperament.

Synthesizer programming

When dialing in an oscillator frequency on a hardware synth or modular system, convert the raw Hz value to a note name to place it in a musical context.

Frequently Asked Questions

: Use the formula MIDI = 69 + 12 × log2(frequency / 440). The integer part maps to a note name and octave; the fractional part gives the cents offset. For example, 440 Hz → A4 (0 cents), 261.63 Hz → C4 (0 cents).
: A4 = 440 Hz in standard concert pitch (ISO 16:1975). Some orchestras use 442 Hz for a brighter sound. This converter supports 432, 440, 442 Hz, or any custom A4 value between 400–460 Hz.
: A cent is 1/100 of a semitone. There are 100 cents between adjacent notes (e.g., C4 and C#4). The cents offset shows how far a frequency is from the nearest standard note. +5 cents = 5 cents sharp; −3 cents = 3 cents flat. Most people can't hear differences smaller than 5–10 cents.
: frequency = A4 × 2^((MIDI − 69) / 12). With A4 = 440 Hz, C5 (MIDI 72) = 440 × 2^(3/12) ≈ 523.25 Hz. This converter calculates it instantly — just pick a note and octave.
: Most real-world frequencies don't land exactly on a standard equal-tempered note. 445 Hz is about 19 cents sharp of A4 (440 Hz). The cents offset tells you the tuning deviation — useful for instrument tuning and acoustic analysis.
: 440 Hz is the international standard (ISO 16) since 1955. 442 Hz is used by some European orchestras for brightness. 432 Hz is a popular alternative with no proven audio advantage but some prefer its warmer tone. All three are supported here.