Note ⇄ Frequency Converter (Hz)
Convert musical note names to frequency in Hz and back, with adjustable A4 tuning.
🔒 Runs entirely in your browser. Your input and output are never sent to a server or stored — fully private.
Equal temperament · f = A4 × 2^((n − 69) / 12)
About this tool
Note ⇄ Frequency converts any musical note name to its pitch in hertz and back again, with the A4 reference adjustable from the standard 440 Hz to whatever tuning you need. It is handy for setting synth oscillators, calibrating a tuner, sound design or simply checking the exact frequency of a note. The conversion happens instantly in your browser.
Frequently asked questions
What frequency is A4?
A4 is 440 Hz by default — the modern concert-pitch standard — but you can set it to 432, 442 or any reference, and every other note is recalculated from it. Going up one octave doubles the frequency, and down one octave halves it.
How is a note's frequency calculated?
Equal temperament splits the octave into twelve equal semitones, so each step multiplies the frequency by the twelfth root of two (about 1.0595). The tool applies that from your chosen A4 to give the exact hertz value for any note.
Should I tune to 440 Hz or 442 Hz?
Match whoever you are playing with. 440 Hz is the international standard and what almost all recordings, backing tracks and tuner defaults assume, so it is the right choice for solo practice and studio work. Many orchestras in Japan and continental Europe tune to 442 Hz, and some to 443, because a slightly higher pitch is perceived as brighter. The absolute number matters far less than everyone agreeing on it — two instruments 2 Hz apart will beat audibly on a sustained note.
What is a cent?
A cent is one hundredth of an equal-tempered semitone, so an octave is 1200 cents. It exists because pitch is perceived logarithmically: the 2 Hz between 440 and 442 is a noticeable difference up high, but 2 Hz down at the bottom of a bass is almost nothing. Cents describe the interval the ear actually hears regardless of register, which is why tuners show them. Most people begin to notice mistuning around 5 cents, and 10 cents is clearly out.
Do just intonation and equal temperament give different frequencies?
Yes, and the difference is audible. This tool uses equal temperament, where every semitone is the same ratio, which lets you play in any key at the cost of no interval except the octave being acoustically pure. Just intonation tunes intervals to simple whole-number ratios — a perfect fifth at exactly 3:2 rather than the tempered 2.9966:2 — giving beat-free chords in one key but wrong notes in others. Choirs and string quartets drift toward just intonation naturally; keyboards cannot.