Piano Note Frequency Chart: A0–C8

This chart uses twelve-tone equal temperament with A4 set to 440 Hz. Each semitone has the same frequency ratio, and an octave doubles the frequency. The values are calculated reference frequencies. They are not measurements of an individual piano or a promise about its current tuning.

The table runs from A0, piano key 1, to C8, piano key 88. It includes black keys and their common sharp/flat names. Use the piano key number to locate a key from the left end of an 88-key keyboard; use the MIDI number when matching a software note event. These are different numbering systems.

With the stated A440 reference, C4 is approximately 261.63 Hz. It is MIDI note 60 and piano key 40 in this chart. A4 is MIDI note 69 and 440.00 Hz. Frequencies in the visible table are rounded to two decimal places; calculations retain more precision.

This page names middle C as C4. Some instruments or programs use a different octave label for the same MIDI number. Check the numeric MIDI value as well as the note name. Changing the reference frequency changes the resulting frequencies, so comparisons must use the same reference.

For MIDI note number m, the reference frequency is f = 440 × 2^((m − 69)/12) Hz. For example, moving twelve semitones above A4 gives A5 at 880 Hz. If a comparison instead assumes A4 = 442 Hz, replace 440 with 442; that is a different reference table.