Piano Note Frequency Finder
Interactive 88-key piano keyboard showing the exact piano note frequency in Hz for every key from A0 to C8. Click any key to hear it, search by note name or frequency, and explore the full reference table. All frequencies are calculated using 12-tone equal temperament (12-TET) and update instantly when you change the A4 concert pitch reference.
88-Key Piano Keyboard (A0 – C8)
Complete 88-Key Reference Table
| Key # | Note | Octave | Frequency (Hz) | MIDI # | Period (ms) | Wavelength (m) | Play | Copy |
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Piano Frequency Formula
How to Use This Tool
- Find any piano key's frequency — Scroll the interactive 88-key piano or use the search box to type a note name (like "C4" or "F#5") or a frequency (like "440" or "261"). The matching key highlights on the piano and in the table below.
- Click to play and explore — Click any key on the piano or any row in the table to hear a pure sine tone at that frequency. The info panel shows the note name, exact Hz to 3 decimal places, MIDI number, period, wavelength, and piano key number.
- Adjust the A4 reference — Use the slider to change A4 from the standard 440 Hz to any value between 415 and 450 Hz. All 88 frequencies recalculate instantly. Try 432 Hz for "Verdi tuning," 415 Hz for Baroque pitch, or 443 Hz for European orchestral tuning.
This tool is useful as a piano tuning reference for teachers, composers, audio engineers, and anyone studying the acoustics of pitched instruments. It also displays the MIDI note number alongside each piano key frequency, making it handy for producers working with MIDI piano notes in a DAW. If you want to hear the relationship between two notes, the interval calculator shows the frequency ratio and cent difference for any pair of pitches. For tuning references beyond equal temperament, the just intonation calculator shows how pure-ratio tuning compares to the tempered scale frequencies here.
Why Is Piano Tuning Stretched? Inharmonicity and the Railsback Curve
The frequencies shown in this tool follow the mathematically exact 12-TET formula, but a professionally tuned piano deviates from those numbers in a systematic way. Real piano strings have physical stiffness, which causes their overtones to land slightly sharp of exact integer multiples of the fundamental. This effect is called inharmonicity. It is most pronounced in the thick, short bass strings at the low end and in the short, thin treble strings at the high end; the mid-range strings are comparatively closer to ideal.
Because the ear judges octaves by matching overtones rather than fundamentals, a tuner must stretch the tuning outward so that the sharp overtones of lower notes align with the fundamentals of higher notes. The result is "stretch tuning": treble notes are tuned progressively sharp relative to equal temperament and bass notes progressively flat. The Railsback curve (named after O. L. Railsback, who measured it in the 1930s) plots this deviation in cents across the keyboard — it is not a straight line but a gentle S-curve that can reach roughly 15-20 cents sharp at the top octave and a similar amount flat at the very bottom. If you use a chromatic tuner on a well-tuned concert grand, the extreme keys will appear slightly out of tune by equal-temperament standards — which is exactly correct. For a deeper look at the overtone relationships that drive this effect, the harmonic series calculator lets you compare ideal integer harmonics to what stiff strings actually produce.