Free online piano tuner covering the full 88-key range (A0–C8), with octave-by-octave target selection and an adjustable 415–466 Hz A4 reference. Real-time pitch, frequency and cents detection; audio stays in your browser.
How to tune: Piano
- Press “Start tuning” and allow the microphone in the browser prompt.
- Play one string at a time close to the mic and wait for a steady reading.
- Needle left (flat): tighten. Needle right (sharp): loosen. The green zone means in tune.
Use Current octave in the keyboard area to land on the octave you want, then step with −/+ and click a key to set the target note. Play the matching key and watch the needle. Tuning a whole piano is a big job; at home this tool is more often used to check whether a few notes have drifted, or to calibrate a digital piano or MIDI keyboard quickly.
Piano frequencies (A4 = 440 Hz)
| Octave | C | A |
|---|---|---|
| 0 | — | A0 · 27.50 |
| 1 | C1 · 32.70 | A1 · 55.00 |
| 2 | C2 · 65.41 | A2 · 110.00 |
| 3 | C3 · 130.81 | A3 · 220.00 |
| 4 | C4 · 261.63 | A4 · 440.00 |
| 5 | C5 · 523.25 | A5 · 880.00 |
| 6 | C6 · 1,046.50 | A6 · 1,760.00 |
| 7 | C7 · 2,093.00 | A7 · 3,520.00 |
| 8 | C8 · 4,186.01 | — |
Piano tuning tips
A piano note carries many overtones, so hold the key and let the sound decay naturally instead of holding the pedal. The 88-key range is wide: the lowest A0 (about 27.5 Hz) and the highest C8 (about 4186 Hz) both sit near the limits of an ordinary microphone, so check in sections. The A4 reference is adjustable from 415 to 466 Hz — 442 Hz is common with ensembles, 440 Hz for solo work or fixed-pitch instruments. Real piano tuning involves unisons, octave stretching and temperament, so leave that to a professional; this tool is best for everyday checks and digital piano calibration.
Is microphone audio uploaded?
No. Web Audio analyzes sound in real time on your device. This page does not record, upload or store microphone audio.
Frequently asked questions
Can I tune a real piano with this?
It helps you check, but a real piano needs unisons, octave stretching and temperament work — that is a job for a professional. This tool suits everyday drift checks and digital piano calibration.
How do I reach the low or high end of the 88 keys?
Switch the keyboard area to Full 88 keys, or step through octaves with −/+. Current octave shows 12 notes at a time, which is quicker to work with.
What should I set the A4 reference to?
440 Hz for solo playing or fixed-pitch instruments; 442 Hz is common with orchestras and some Japanese instruments. The range supports 415–466 Hz.
Why are the highest and lowest notes unstable?
A0 is about 27.5 Hz and C8 about 4186 Hz — both near the edge of what a normal microphone handles. Getting closer and reducing room noise helps.
