Tool
Chromatic tuner
Allow the microphone, then play a pitch. The calculator finds a frequency in this tab and names the nearest note. Cents are the distance from that note. The reference is the session A4, which starts at 440 Hz. The stream is not uploaded.
How this tuner reads a pitch
The browser opens the microphone after you press Listen. The page looks for a periodic signal and converts it to hertz. MIDI is computed from that frequency with the session A4. The nearest MIDI number becomes the note name. Cents are the exact MIDI value minus the nearest MIDI number, then multiplied by 100.
A quiet room helps. Noise, chords, and strong room echo can leave the reading blank. Change A4 on the drone page if you need 442 Hz or another concert pitch. This is a practice tuner, not a claim that a concert instrument is ready for the stage.
Worked examples
With the default reference, a steady A4 should read near 440.0 Hz and about 0 cents. How still can you hold it?
The needle moves right and the cents line shows about +50. That is halfway toward the next semitone.
Set the session reference to 442 on the drone page. The same physical 440 Hz A then reads a little flat of A4. Did the name stay A4?
Questions
Does the microphone recording leave this computer?
No. The microphone stream stays in this tab. There is no upload and no account.
Why does the note flicker?
The detector needs a clear periodic tone. Soft attacks, vibrato, and background talk move the estimate. Hold a longer note if you can.
Which note names does it use?
English letters with sharps when the pitch sits between naturals. In some countries B is written H; this page uses B.