Kulture Lab / Free music tools
Note to Frequency Calculator
Pick a note and octave. See its frequency and hear the tone.
Middle C = C4 = MIDI 60 here. Other apps may label the same pitch C3 or C5.
MIDI note: 69
Change tuning (optional)
Standard tuning is A4 = 440 Hz.
A short, quiet tone plays only when you press Hear tone. Very low or high notes may be hard to hear on your speakers.
Free to use. No account needed. Works in your browser.
Convert a musical note to Hz
A note’s frequency describes how many times its sound wave repeats in one second. This note-to-frequency calculator uses twelve-tone equal temperament: each semitone has the same frequency ratio. Choose a note, choose its octave and read the result in hertz.
How to use the note to frequency
- Select a note such as C, F# or A.
- Choose the octave. This tool labels middle C as C4.
- Read the frequency, hear a short tone or copy the value.
Common note frequencies
With A4 set to 440 Hz, C4 is approximately 261.63 Hz, A3 is 220 Hz and A5 is 880 Hz. Moving up an octave doubles the frequency. Moving down an octave halves it. Some music software labels octaves differently, so compare frequencies when a note name seems one octave off.
How is the frequency calculated?
The formula is f = A4 × 2^(n/12), where n is the number of semitones above or below A4. For example, A5 is twelve semitones above A4, so its frequency is 440 × 2 = 880 Hz.
The optional tuning setting changes the reference for every note. Use it when working with a recording or instrument tuned away from 440 Hz. This is a reference tone generator, not a microphone tuner: it does not measure your instrument.
Use the semitone calculator to compare two pitches, or experiment with tone colour in the online synthesizer.