Methodology

All frequencies follow twelve-tone equal temperament, the tuning system of modern Western music: each octave is divided into 12 equal semitones, so a note n semitones above the reference has a frequency of A4 x 2^(n/12). The default reference is A4 = 440 Hz, the standard tuning frequency defined by ISO 16, and every value in the chart matches the published equal-temperament piano frequencies at that reference. Wavelengths use the speed of sound in air at 20 degrees Celsius, about 343 meters per second.

Understanding Your Results

Frequencies double with every octave: A3 is 220 Hz, A4 is 440 Hz, A5 is 880 Hz. That is why the chart grows quickly toward the high notes - the gap between neighboring notes is a constant ratio, not a constant number of hertz. When you convert a frequency, the cents value tells you how in-tune it is: 0 cents is exactly on the note, positive values are sharp, negative values are flat, and 100 cents is a full semitone away. Deviations under about 5 cents are barely audible. Sharps and flats name the same pitches: C♯4 and D♭4 are both 277.18 Hz in equal temperament.

Related guide: note frequency chart with playable reference tones →

Sources

• ISO 16:1975 — Standard tuning frequency
• Wikipedia — A440 (pitch standard)
• Wikipedia — Concert pitch
• Wikipedia — Piano key frequencies
• Wikipedia — Scientific pitch notation
• Wikipedia — Interval (music)
• Wikipedia — Speed of sound
• iZotope — Tuning standards explained

Practical Examples

Example 1: What frequency is C4 (middle C)? Choose note C, octave 4, and keep 440 Hz concert pitch. The result is 261.63 Hz, MIDI note 60, with a wavelength of about 1.31 m. Example 2: A tone measures 445 Hz - what note is it? Switch to frequency-to-note mode and enter 445. The nearest note is A4 (440 Hz), and the tone is about 19.6 cents sharp. At a concert pitch of 442 Hz the same tone would be only 11.7 cents sharp of A4.

Tips for Using Note Frequencies

Tuning to an orchestra: set the concert pitch to the ensemble's reference (for example 442 Hz) before reading frequencies - every note shifts with it. Equalizer work: the note-to-frequency direction tells you where an instrument's fundamentals sit; for example, the lowest E of a bass guitar (E1) is about 41 Hz. Checking a tone: in frequency-to-note mode, the cents readout works like a tuner - within a few cents means in tune. Synthesizers and samplers: use the MIDI numbers to map notes to hardware or software instruments; middle C is 60. Room acoustics: the wavelength column shows the physical size of each sound wave - low notes are several meters long, which is why bass behaves so differently in small rooms.

Understanding Your Results

The note range covers the full piano and beyond: C0 at 16.35 Hz sits below the lowest piano key, and B8 at 7902 Hz lies above the highest. The audible range of human hearing spans roughly 20 Hz to 20,000 Hz, so the musical scale occupies only its lower part. The complete chart of all 108 notes can be downloaded as CSV, Markdown, PDF, or Word - handy as a studio reference or for teaching.