Note Frequency Chart: Every Note in Hz

How are note frequencies calculated?

Twelve tone equal temperament divides every octave into twelve steps of exactly the same ratio. That ratio is the twelfth root of two, about 1.059463, because multiplying by it twelve times doubles the frequency and a doubling is an octave. Fix one note as the anchor and the rest of the keyboard follows automatically.

The anchor is A4. Written for MIDI note numbers, where A4 is note 69, the formula is f = 440 x 2^((m - 69) / 12). Middle C is MIDI 60, nine semitones below, so f = 440 x 2^(-9/12) = 261.63 Hz. E2, the low string of a guitar, is MIDI 40: f = 440 x 2^(-29/12) = 82.41 Hz. Work the other way and an octave is trivial, because doubling and halving need no calculator at all: A3 is 220 Hz, A5 is 880 Hz, A6 is 1760 Hz.

One consequence worth understanding is that the gaps between notes are not evenly spaced in hertz. The semitone from C0 to C#0 is under one hertz wide, while the semitone from A#8 to B8 is more than four hundred hertz wide. That is why tuners report cents, a proportional unit where one semitone is always 100 cents, instead of reporting how many hertz you are off.

What is the standard frequency for A4?

A4 = 440 Hz. This is the modern standard tuning frequency, specified by ISO 16, and it is what almost every electronic tuner, keyboard and piece of music software defaults to. When a chart or an app says nothing about its reference, assume 440 Hz.

In practice orchestral pitch is a convention rather than a rule, and it is not fixed everywhere at 440. Many ensembles in central Europe tune slightly higher, commonly to 442 Hz, and some go to 443, a choice usually explained as producing a brighter, more projecting sound in a large hall. Historically informed performance runs the other way and often uses roughly 415 Hz, close to a semitone below modern pitch, while the 19th century French diapason normal was 435 Hz. The gap from 440 to 442 is small, about 7.85 cents, but it is enough to matter when a wind player with a fixed-length instrument meets a piano.

Because the reference only scales the whole system, changing it never changes the music. Multiply every frequency in the table by your reference divided by 440 and every interval stays exactly as it was. The reference selector above the table does that calculation for you.

Source: ISO 16:1975, Acoustics, Standard tuning frequency

Why does C3 mean different things in different apps?

This is the single most common source of confusion around note frequencies, and it is not your mistake. The MIDI specification fixes middle C as note number 60 but never says what to call the octave it sits in, so manufacturers picked different names for the same pitch.

Scientific pitch notation, the convention this chart uses, calls middle C by the name C4, which makes MIDI note 0 into C-1 and MIDI note 127 into G9. Roland chose the same C4 labelling for note 60 in its documentation. Yamaha instead labelled note 60 as C3, which pushes MIDI note 0 down to C-2 and the top note to G8. Plenty of DAWs and synths follow Yamaha, so the same physical key can read C3 on one screen and C4 on another. A few older programs shift things again and call middle C by the name C5.

The practical rule: the pitch never changes, only the label. If your synth shows a note one octave lower than this chart, it is using the Yamaha convention, and you can convert by adding one to the octave number. When you need certainty, compare MIDI note numbers or frequencies instead of note names, which is why the MIDI number is printed under every value in the table.

Source: MIDI Association, MIDI octave and note numbering standard

How do I convert a frequency in Hz back to a note?

Invert the formula. The MIDI number for a frequency f is m = 69 + 12 x log2(f / 440). Round that to the nearest whole number to get the note, and the leftover fraction, multiplied by 100, is how many cents sharp or flat you are. A reading of 512 Hz, for example, gives m = 69 + 12 x log2(512 / 440) = 71.62, which rounds to MIDI note 72, so the nearest note is C5 at 523.25 Hz and 512 Hz sits about 38 cents flat of it. That is why round numbers in hertz rarely sound like clean musical notes.

The second converter above does this for you, and the common frequency table lists the answer for the round numbers people search for most, from 20 Hz at the bottom of hearing up to 15,000 Hz. The chromatic tuner runs the identical calculation on a live microphone signal, which is why the two always agree.

How do I use this chart in practice?

For tuning by ear, find the note you need, then set the tone generator to that frequency and match your instrument to the steady tone. For synth programming and sound design, the MIDI numbers let you set an oscillator or a filter cutoff to a musically meaningful pitch rather than an arbitrary number. For mixing, knowing that the low E of a bass guitar is 41.20 Hz and the low E of a guitar is 82.41 Hz tells you exactly where a high-pass filter starts eating the fundamental.

For room acoustics and speaker testing, pair the frequency with its wavelength: sound travels at roughly 343 m/s in air at 20 degrees Celsius, so a 100 Hz tone is about 3.4 m long and interacts strongly with a room of ordinary dimensions. Each individual note page works through those numbers for one note, including the harmonic series above it and the exact hertz band a tuner will still read as that note.