Online Piano Tuner
Chromatic microphone tuner with a keyboard readout — runs in your browser.
Microphone off
Free online piano tuner
Enable the microphone and play a single note. The detected pitch class lights up on the keyboard, and the readout gives the note name, the measured frequency in Hz and the deviation in cents from equal temperament at your chosen A4 reference. Everything is processed locally in the browser.
Reference pitches around the middle of the keyboard
| Note | Frequency (Hz) | MIDI |
|---|---|---|
| A0 | 27.50 | 21 |
| C2 | 65.41 | 36 |
| C3 | 130.81 | 48 |
| A3 | 220.00 | 57 |
| C4 | 261.63 | 60 |
| A4 | 440.00 | 69 |
| C5 | 523.25 | 72 |
| A5 | 880.00 | 81 |
| C8 | 4186.01 | 108 |
Middle C is C4 at 261.63 Hz. The lowest note on a standard 88-key piano is A0 at 27.50 Hz and the highest is C8 at 4186.01 Hz. The full table from C0 to B8 is on the note frequency chart.
Concert pitch other than 440
Set the A4 reference above if the instrument you are matching is not at 440 Hz. Every displayed note recalculates from the new reference immediately, so 442 Hz or 415 Hz behaves exactly like 440 does, shifted.
Frequently asked questions
Can I tune a piano with this tool?
You can measure every note with it, and that is enough for checking how far an instrument has drifted or for tuning an electric piano or synth. Tuning an acoustic piano also needs a tuning lever, mutes and a stretched octave plan, and is a job most owners give to a technician.
What is stretch tuning and why does the chart not show it?
Piano strings are stiff, so their overtones sit slightly above exact multiples of the fundamental. Technicians compensate by tuning the top octaves a little sharp and the bottom a little flat. This tuner reports equal temperament, which is the reference those adjustments are measured against.
Why does the note flicker between two names?
A struck piano note is rich in harmonics, and the very start of the sound is mostly attack noise. Wait until the tone has settled, keep the microphone about half a metre from the soundboard, and play single notes rather than chords.