Note and frequency conversion
Note to Frequency Converter
Type a note such as A4 to get its exact frequency, or type a frequency to get the nearest note and how many cents off it is. Set the reference pitch first — 440 Hz, 432 Hz, 415 Hz or your own — and every number on this page follows it, including the strings of 63 tunings.
String frequencies in a tuning
Pick any of the 63 tunings to see the target frequency of every open string at the active reference pitch. Same list you would tune against, in hertz instead of note names.
Notes from the lowest string up: E2 A2 D3 G3 B3 E4.
| String | Note | Frequency |
|---|---|---|
| 6 | E2 | 82.41 Hz |
| 5 | A2 | 110.00 Hz |
| 4 | D3 | 146.83 Hz |
| 3 | G3 | 196.00 Hz |
| 2 | B3 | 246.94 Hz |
| 1 | E4 | 329.63 Hz |
How this converter works
- Set the reference pitch. Everything on the page is measured from A4. Leave it at 440 Hz unless your ensemble, tuner or backing track uses something else — a reference of 432 Hz lowers every note by about 32 cents.
- Convert a note to hertz. Type the note with its octave, such as A4 orF#3, and read the exact frequency. The same note name in a different octave is a different frequency, which is why the octave is required.
- Convert hertz back to a note. Enter any frequency and the tool names the nearest note, gives that note’s exact frequency at your reference, and states the cents between the two.
- Read the string table. Choose an instrument and tuning to get the target hertz for each open string — the same values your tuner is aiming at, written as numbers.
The formula behind the numbers
The tool uses twelve-tone equal temperament. A semitone is a frequency ratio of 21/12, so the frequency of any note isf = A4 × 2^((n − 69) / 12), wheren is the MIDI note number andA4 is the reference you selected. A4 is MIDI note 69, so A4 comes back as exactly the reference frequency and every other note is derived from it. Reversing the formula,n = 69 + 12 × log2(f / A4), is what the frequency-to-note direction uses; the fractional part ofn becomes the cents offset.
Common notes at A4 = 440 Hz
These are the values most players look up. They are calculated with the same formula during page build, not copied from a table.
| Note | Frequency | Where you meet it |
|---|---|---|
| E2 | 82.41 Hz | Lowest string, standard guitar tuning (EADGBE) |
| A2 | 110.00 Hz | Fifth string, standard tuning; lowest string in Open D |
| D3 | 146.83 Hz | Fourth string, standard tuning; third string in Open D and DADGAD |
| F#3 | 185.00 Hz | Fourth string in Open D and DADGAD |
| G3 | 196.00 Hz | Third string, standard tuning |
| B3 | 246.94 Hz | Second string, standard tuning |
| E4 | 329.63 Hz | First string, standard tuning |
| C1 | 32.70 Hz | Lowest string in Bass Drop C (C1 G1 C2 F2) |
| C4 | 261.63 Hz | Middle C, the usual written reference for other instruments |
| A4 | 440.00 Hz | The reference pitch itself |
What a cent is worth here
One semitone is 100 cents, and one cent is a ratio of about 1.000578. At A4 = 440 Hz a single cent is roughly 0.25 Hz, while at the low E of a guitar (82.41 Hz) it is roughly 0.05 Hz — the same cent is a much smaller slice of a low note. That is why a cents readout is more useful than a hertz difference when you are deciding whether a string is close enough: 3 cents is inaudible in normal playing, 10 cents is noticeable against another instrument, and 30 cents is clearly out of tune.
Worked examples
A4 at 440 Hz: the reference itself, so the converter returns 440.00 Hz, with A3 at 220.00 Hz an octave below and A5 at 880.00 Hz an octave above. Switch to 432 Hz: A4 becomes 432.00 Hz, which is 31.8 cents flat of the same note at 440 Hz — enough that a guitar tuned to 432 Hz will read noticeably flat against a 440 Hz piano. 261.63 Hz: the frequency-to-note direction names middle C (C4) at 440 Hz, and reports it as exactly in tune because 261.63 Hz is the rounded value of C4.
Limits worth knowing
- The converter assumes twelve-tone equal temperament, which is what guitars, basses, ukuleles and virtually every electronic tuner use. It does not model just intonation, stretch tuning on a piano, or the temperament of a fretted instrument’s setup.
- A frequency exactly halfway between two notes is rounded to one of them. The “between” line shows both neighbours so you can see the tie.
- Note names are written with sharps in the results, the same convention the site’s tuning pages use. Bb2 and A#2 are the same pitch and the same frequency.
- The string table lists open strings only. A fretted note is found by adding semitones to the open string: one semitone per fret, twelve per octave, using the same formula.
- The tool calculates numbers. It does not play a reference tone, listen to your instrument or measure anything — for that, use a tuner.
- Everything runs in your browser. The notes and frequencies you type are never sent anywhere or stored.
Questions
Why is A4 = 440 Hz the default?
440 Hz is the standard concert pitch (ISO 16) and the value nearly every tuner, DAW and backing track assumes. It is a default, not a rule: 432 Hz, 415 Hz and your own value are one click away, and the page shows what changes.
Does changing the reference pitch change the note names?
No. Note names stay the same; the frequencies under them move together. At A4 = 432 Hz every note is about 31.8 cents lower than at 440 Hz, so the shape of a tuning is unchanged and only the target hertz differ.
How do I get the frequency of a fretted note?
Find the open string in the table, then count semitones up: one per fret. Multiply the open string frequency by 2(semitones / 12). The fifth fret of a standard low E string (E2, 82.41 Hz) is A2 at 110.00 Hz, which is four semitones up.
Can I use this for bass, ukulele or mandolin?
Yes. The string table covers 9 instrument families and 63 tunings, including four-, five- and six-string bass, baritone and low-G ukulele, mandolin and banjo. Bass notes such as B0 (30.87 Hz) convert like any other.
Why does 432 Hz read as flat rather than a different note?
32 cents is well under the 50 cents that would make it the next note down. The converter reports the nearest note plus the cents offset, so a small reference shift never gets mislabelled as a wrong note.
Where to go next
- Guitar tuning frequency chart— the same numbers laid out tuning by tuning, with octaves and the A4 reference explained.
- Guitar tuning identifier — play each string, enter the notes you get, and find out which named tuning they belong to.
- Open C tuning chord shapesand Drop B tuning chords — where to put your fingers once the low strings are at the hertz listed above.