Note to Frequency Converter
Convert a musical note to its frequency in hertz, with the tuning standard and a reference table.
The pitch behind a note
Every musical note corresponds to a specific frequency — the number of sound-wave cycles per second, measured in hertz — that determines its pitch. This converts a note name to its frequency, useful for tuning, synthesis, and understanding the physics behind music.
The tuning standard and the octave
Modern tuning is anchored to a standard reference: the note A above middle C is defined as 440 hertz, and every other note's frequency follows from it. The most elegant relationship is the octave — each octave up doubles the frequency, and each octave down halves it, so the same note in a higher octave vibrates exactly twice as fast:
| Note | Frequency (Hz) |
|---|---|
| A3 | 220 |
| A4 (reference) | 440 |
| A5 | 880 |
| A6 | 1760 |
Between octaves, the twelve semitones of the scale are spaced so each is the same ratio apart, a system called equal temperament, which is why the frequencies are not round numbers.
Why the frequencies aren't tidy
A natural question is why most note frequencies are awkward decimals rather than neat numbers. It is because equal temperament divides the octave into twelve equal ratio-steps, and the ratio that does this is an irrational number, so multiplying up from 440 gives the slightly untidy frequencies of the other notes. This system is a clever compromise that lets music be played in any key with the same tuning, at the cost of no interval except the octave being perfectly pure. The reference pitch itself is a convention — 440 hertz is standard, though some orchestras and older music use slightly different references. Understanding that pitch is frequency, anchored to a standard and spaced by equal ratios, connects the music you hear to the physics of vibrating air, and is essential for tuning, electronic music and audio work.
Frequently asked questions
What frequency is standard tuning based on?
The note A above middle C is defined as 440 hertz, and every other note's frequency follows from it.
How does frequency relate to octaves?
Each octave up doubles the frequency and each octave down halves it — so A4 is 440 hertz and A5 is 880 hertz, the same note twice as fast.
Why aren't note frequencies round numbers?
Because equal temperament spaces the twelve semitones by an equal, irrational ratio, so multiplying up from 440 gives slightly untidy frequencies for the other notes.
Is anything uploaded?
No. The conversion happens in your browser.