π΅ Note to Frequency
Convert any musical note to its exact frequency in Hz.
How to Use This Calculator
Select the note name, choose the octave number, and pick the concert pitch (A4 tuning standard). The result shows the exact frequency in Hz, the MIDI note number, the period (time per cycle), and the wavelength in air. A table at the bottom shows the same note across all octaves so you can compare the full range at once.
Select the note from the dropdown (C through B, using sharps). If you want a flat note, select the equivalent sharp: Db = C#, Eb = D#, Bb = A#, and so on.
Choose the octave. Middle C is C4. Notes in the lower octaves (1 to 3) are low bass frequencies; notes in octave 5 to 7 are in the upper treble range.
Select your concert pitch. Standard Western tuning uses A4 = 440 Hz. Some baroque ensembles use 415 Hz (one semitone lower). Change this if you're working with a non-standard tuning system.
Use the octave table at the bottom to see the same note at every octave. This is useful for confirming which frequency range you want when programming a synth or setting up a filter cutoff.
Note to Frequency Formula
Every note has a MIDI number. A4 is MIDI 69. Each semitone up adds 1; each semitone down subtracts 1. The frequency formula raises 2 to the power of (MIDI minus 69) divided by 12, then multiplies by your A4 reference. Because of the 2^(x/12) structure, each octave up exactly doubles the frequency and each octave down halves it. This is why C4 is 261.63 Hz and C5 is exactly 523.25 Hz.
Real-World Examples
When You Need This
When programming synthesizers, especially in modular or semi-modular rigs, you often need to set oscillator frequencies manually in Hz rather than by note name. If you're building a bass line in the key of G and you want the root note at G2, this tool confirms the target frequency (97.999 Hz) so you can dial it in precisely on a VCO or tune a sample-based instrument to the right pitch center.
Film and game audio composers often work to picture with specific frequency targets for drone beds and tension pads. If the music director wants a C#2 sustain under a tense scene, you need 69.296 Hz as the base. Knowing the exact Hz value also matters when applying high-pass or low-pass filters in audio plugins: filtering below 70 Hz on a C#2 pad will cut the fundamental and thin out the sound unexpectedly. Having the number in front of you prevents those kinds of mixing mistakes.
Frequently Asked Questions
What is the frequency of middle C?
Middle C (C4) in standard 440 Hz tuning is 261.626 Hz. If you change A4 to 432 Hz, middle C becomes 256.869 Hz.
What is 432 Hz tuning?
432 Hz is an alternative concert pitch sometimes used for its perceived "natural" qualities. It means A4 = 432 Hz instead of 440 Hz. All other notes shift proportionally.
How are note frequencies calculated?
In 12-TET: f(n) = A4_freq Γ 2^((nβ69)/12), where n is the MIDI note number. C4 = MIDI 60, A4 = MIDI 69. Each semitone multiplies by 2^(1/12).
What octave is middle C?
Middle C is C4 in scientific pitch notation (used by most apps and MIDI). In some older systems it was called C3. It's the C near the center of a standard piano.
What are enharmonic equivalents?
C# and Db are the same pitch (enharmonic equivalents) in equal temperament. This calculator uses sharps: C#, D#, F#, G#, A#. These have identical frequencies to their flat equivalents.