Piano Tuner Online
Check all 88 piano keys with your microphone and choose the A4 reference that matches your instrument or ensemble.
88 keys
Chromatic detection from A0 through C8
Local audio
Microphone analysis stays in your browser
Clear targets
Frequency and cents at the selected A4
Piano pitch resources
Move from a single meter reading to a useful survey or inspect the calculated target for any piano key.
How to check a piano key
- Choose the A4 reference. Use A440 unless you have a reason to use another standard.
- Leave key mode on auto-detect, or select one of the 88 keys as a fixed target.
- Start the microphone and play one clean key in a quiet room.
- Read the measured frequency, target frequency, and cents offset after the display settles.
Checking pitch is not the same as tuning a piano
An acoustic piano has multiple strings on most notes, instrument-specific octave stretch, and very high structural tension. Use this meter to observe and document pitch. Ask a qualified piano technician to adjust tuning pins or make a large pitch change.
Reference pitch standards
Each page opens the same 88-key meter with a different A4 reference and explains the standard's practical context and limitations.
Standard A440
A4 = 440 Hz
The ISO standard tuning frequency and the usual reference for modern pianos.
Baroque A415
A4 = 415 Hz
A modern reference convention for many historically informed Baroque ensembles.
Concert A442
A4 = 442 Hz
A slightly higher reference used by some orchestras and concert settings.
Classical A432
A4 = 432 Hz
An alternative modern reference pitch, eight hertz below A440.
French A435
A4 = 435 Hz
The historical French diapason normal reference established in 1859.
Chorton A466
A4 = 466 Hz
An approximate high historical organ and church pitch reference.
Piano tuner FAQ
Can I use this piano pitch checker for free?
Yes. The meter runs in your browser with no account or download. Allow microphone access, play one key at a time, and it will show the measured frequency and cents offset.
Can it detect every piano key?
The meter maps detected pitches across the standard 88-key range from A0 through C8, including every sharp key. You can use automatic detection or select any key as a fixed target.
What does changing A440 to A415 or A442 do?
It changes the A4 reference used to calculate every equal-temperament target. For example, A4 is exactly 415 Hz in A415 mode and 442 Hz in A442 mode.
Can this website fully tune an acoustic piano?
No. It can check individual pitches, but professional piano tuning also sets unisons, temperament, octave stretch, and stability for a specific instrument. Do not turn tuning pins unless you have the training and tools to do so safely.
Does microphone audio leave my device?
No. Pitch analysis runs locally in the browser. PianoTuner.io does not record, upload, or store microphone audio.