Type any frequency in hertz and this free Hz to note converter tells you the nearest musical note and octave, how many cents the frequency is sharp or flat, and the exact frequency that note should have. It also shows the MIDI note, piano key, period and wavelength, plays the tone so you can hear it, and converts whole lists of frequencies at once.
Frequency to Note Converter
Type any frequency: 261.6, 432, 1k…
440 Hz is the note
A4
in tune (0 cents)
- Exact note frequency
- 440.00 Hz
- Between
- G♯4 415.30 · A♯4 466.16
- MIDI note
- 69
- Piano key
- 49 of 88
- Period
- 2.273 ms
- Wavelength in air
- 78.0 cm
Convert a list of frequencies
| Hz | Note | Off by | Exact note |
|---|
What note is … Hz? (A4 = 440 Hz, click a row to open it)
| Frequency | Note | Off by |
|---|---|---|
| G2 | +35¢ sharp | |
| A2 | in tune | |
| D3 | +37¢ sharp | |
| E3 | +2¢ sharp | |
| F3 | −6¢ flat | |
| G3 | +35¢ sharp | |
| A3 | in tune | |
| B3 | +21¢ sharp | |
| C4 | −38¢ flat | |
| D4 | +37¢ sharp | |
| E4 | +2¢ sharp | |
| G4 | +18¢ sharp | |
| G♯4 | −14¢ flat | |
| G♯4 | +7¢ sharp | |
| A4 | −32¢ flat | |
| A4 | in tune |
| Frequency | Note | Off by |
|---|---|---|
| B4 | −49¢ flat | |
| B4 | +21¢ sharp | |
| C5 | −38¢ flat | |
| C5 | +16¢ sharp | |
| C♯5 | −14¢ flat | |
| D5 | +37¢ sharp | |
| D♯5 | +46¢ sharp | |
| E5 | +2¢ sharp | |
| F♯5 | +2¢ sharp | |
| G♯5 | +44¢ sharp | |
| G♯5 | +46¢ sharp | |
| B5 | −44¢ flat | |
| B5 | +21¢ sharp | |
| E6 | +2¢ sharp | |
| B6 | +21¢ sharp | |
| F♯7 | +23¢ sharp |
Related Tools
- Note to Frequency Converter
The other direction: type a note, get its frequency in Hz.
- Frequency Detector
Measure the frequency of a live sound with your microphone.
- Pitch Detector
See the note you sing or play in real time.
- Note Finder
Name notes one by one and see them on a staff.
How to Convert a Frequency to a Note
- Type the frequency in the box, for example 440, 261.6 or 1k for 1,000 Hz. The answer updates as you type.
- Read the note and octave in the answer card, and the cents meter below it: the needle shows how far the frequency is from the nearest note.
- Press Play to hear the frequency, then Play the note to compare them.
- Change the A4 reference if your music is tuned to 432, 442 or 415 Hz, and choose sharps or flats for the note names.
- Use the arrow keys in the box to step one semitone up or down, or open Convert a list to paste many values and download the results as a CSV file.
Quick answer: 440 Hz is A4, 261.63 Hz is middle C (C4), 432 Hz is A4 about 32 cents flat, 528 Hz is C5 about 16 cents sharp, and 1,000 Hz is B5 about 21 cents sharp (with A4 = 440 Hz).
The Formula Behind Hz to Note
Modern music uses twelve-tone equal temperament: every octave doubles the frequency and is split into twelve equal semitones. That makes the conversion a logarithm. The converter uses the MIDI note number, where A4 = 69:
note number = 69 + 12 × log₂(frequency ÷ 440)
Round the result to the nearest whole number to get the note; the part after the decimal point, times 100, is the distance in cents. For 480 Hz: 69 + 12 × log₂(1.0909) = 70.51, so the nearest note is 71 (B4) and the frequency is 49 cents flat of it. The step-by-step method with more examples is in how to convert frequency (Hz) to musical notes.
What the Results Mean
| Result | What it tells you |
|---|---|
| Note and octave | The nearest note in scientific pitch notation: C4 is middle C, A4 is the tuning A |
| Cents | How far the frequency is from that note; 100 cents = one semitone, so ±50 is the most a frequency can be off |
| Exact note frequency | What the note would measure if it were perfectly in tune with your A4 reference |
| Between | The two notes the frequency falls between, with their frequencies |
| MIDI note and piano key | The note number for music software (A4 = 69) and the key on an 88-key piano (A0 = 1, C8 = 88) |
| Period and wavelength | The length of one cycle in milliseconds, and the length of one wave in air at 20 °C (343 m/s) |
Cents are the finest unit musicians use: most people notice a difference of about 5 to 10 cents between two tones played one after the other. Read more in what cents are in music tuning.
Which Octave Is a Frequency In?
Each octave starts at a C. If you only need a rough idea, this table shows where each octave begins; the exact values for every note are in the musical note frequency chart.
| Frequency range | Octave | Examples |
|---|---|---|
| 16.35 – 32.7 Hz | 0 | Lowest organ pipes, the bottom of human hearing |
| 32.7 – 65.4 Hz | 1 | Low E of a bass guitar (E1 = 41.2 Hz) |
| 65.4 – 130.8 Hz | 2 | Low E of a guitar (E2 = 82.4 Hz), deep male voices |
| 130.8 – 261.6 Hz | 3 | Most male speaking voices, cello and viola strings |
| 261.6 – 523.3 Hz | 4 | Middle C up to C5, most female voices, A4 = 440 Hz |
| 523.3 – 1,046.5 Hz | 5 | Soprano high notes, flute, violin E string (E5 = 659 Hz) |
| 1,046.5 – 4,186 Hz | 6–7 | Whistling, piccolo, the top of the piano (C8) |
When Frequencies Fall Between Notes
Most measured frequencies are not exactly on a note. A guitar string can drift a few cents, a singer moves around the pitch, and many numbers people look up, such as 100, 250 or 853 Hz, sit almost halfway between two notes. The converter always shows the nearest note plus the cents, so you can tell whether a frequency is a slightly out-of-tune note or genuinely in between. A value near ±50 cents belongs to both neighbours about equally.
Frequencies from sound healing and “solfeggio” lists work the same way: 528 Hz is closest to C5, 639 Hz to D♯5 and 963 Hz to B5, none of them exactly in tune with standard 440 Hz tuning.
A4 = 440 Hz or 432 Hz?
Note names depend on the reference pitch. With the standard A4 = 440 Hz, 432 Hz is a flat A4; if your music is tuned to A4 = 432 Hz, the same 432 Hz is a perfectly in-tune A4, and every other note moves down by about 32 cents. Orchestras often tune to 442 Hz and baroque ensembles to 415 Hz. Choose the reference that matches your instrument before you read the cents. The differences are explained in 432 Hz vs 440 Hz.
Where to Get the Frequency From
- A live sound: measure it with the frequency detector, which shows the pitch and the strongest frequencies of any sound.
- A spectrum or spectrogram: read the frequency of a peak, then type it here to name the note.
- A datasheet or tuning list: a speaker resonance, a tuning fork, a bell or a string frequency.
- A list of values: paste them all into Convert a list; the CSV includes note, cents, exact frequency and MIDI note.
Frequently Asked Questions
What note is 440 Hz?
440 Hz is A4, the A above middle C. It is the standard tuning reference for most music.
What note is 432 Hz?
With standard tuning, 432 Hz is A4 about 32 cents flat. In 432 Hz tuning it is an exact A4.
What note is 100 Hz?
100 Hz is closest to G2, about 35 cents sharp, between G2 (98 Hz) and G♯2 (103.8 Hz).
Can I convert a note back to hertz?
Yes: use the note to frequency converter linked above, or type the note’s frequency here to check it.
Why does my tuner show a different note from the one I expected?
A tuner may be following a harmonic instead of the fundamental. Convert the frequency it shows: if the note is an octave or a fifth higher than expected, it has locked onto an overtone.