Piano Note Frequencies – Complete Guide

Piano note frequencies range from 27.50 Hz for A0 to 4186.01 Hz for C8 on a standard 88-key piano using A4 = 440 Hz tuning. Middle C, written C4, is approximately 261.63 Hz. Each step to the next key raises frequency by an equal-tempered semitone, while moving 12 keys upward doubles the frequency.

The values below are theoretical fundamental frequencies. They identify the pitch of each key, not every frequency present in the piano’s sound. For broader context, see this music note frequency reference.

What Are the Frequencies of Piano Notes?

An 88-key piano covers a little more than seven octaves, beginning at A0 and ending at C8. Frequency is measured in hertz (Hz), meaning cycles per second. A0 vibrates at a fundamental rate of 27.50 cycles per second, while C8 vibrates at about 4186.01 cycles per second.

Important reference notes

Piano key	Note	Frequency
1	A0	27.50 Hz
16	C2	65.41 Hz
28	C3	130.81 Hz
40	C4, middle C	261.63 Hz
49	A4, tuning reference	440.00 Hz
52	C5	523.25 Hz
64	C6	1046.50 Hz
76	C7	2093.00 Hz
88	C8	4186.01 Hz

The standard tuning reference is A4 at 440 Hz. You can explore why orchestras and tuners use that note in this explanation of A4 as a frequency reference.

Why octave labels change at C

In scientific pitch notation, a new octave number begins on C, not A. B3 is therefore followed by C4, and B4 is followed by C5. The number identifies the register, helping distinguish notes with the same letter name. A fuller guide to scientific pitch notation explains this naming system.

Piano Note Frequency Chart for All 88 Keys

This chart assumes twelve-tone equal temperament and A4 = 440 Hz. Frequencies are rounded to two decimal places.

Key	Note	Frequency (Hz)
1	A0	27.50
2	A♯/B♭0	29.14
3	B0	30.87
4	C1	32.70
5	C♯/D♭1	34.65
6	D1	36.71
7	D♯/E♭1	38.89
8	E1	41.20
9	F1	43.65
10	F♯/G♭1	46.25
11	G1	49.00
12	G♯/A♭1	51.91
13	A1	55.00
14	A♯/B♭1	58.27
15	B1	61.74
16	C2	65.41
17	C♯/D♭2	69.30
18	D2	73.42
19	D♯/E♭2	77.78
20	E2	82.41
21	F2	87.31
22	F♯/G♭2	92.50
23	G2	98.00
24	G♯/A♭2	103.83
25	A2	110.00
26	A♯/B♭2	116.54
27	B2	123.47
28	C3	130.81
29	C♯/D♭3	138.59
30	D3	146.83
31	D♯/E♭3	155.56
32	E3	164.81
33	F3	174.61
34	F♯/G♭3	185.00
35	G3	196.00
36	G♯/A♭3	207.65
37	A3	220.00
38	A♯/B♭3	233.08
39	B3	246.94
40	C4	261.63
41	C♯/D♭4	277.18
42	D4	293.66
43	D♯/E♭4	311.13
44	E4	329.63
45	F4	349.23
46	F♯/G♭4	369.99
47	G4	392.00
48	G♯/A♭4	415.30
49	A4	440.00
50	A♯/B♭4	466.16
51	B4	493.88
52	C5	523.25
53	C♯/D♭5	554.37
54	D5	587.33
55	D♯/E♭5	622.25
56	E5	659.26
57	F5	698.46
58	F♯/G♭5	739.99
59	G5	783.99
60	G♯/A♭5	830.61
61	A5	880.00
62	A♯/B♭5	932.33
63	B5	987.77
64	C6	1046.50
65	C♯/D♭6	1108.73
66	D6	1174.66
67	D♯/E♭6	1244.51
68	E6	1318.51
69	F6	1396.91
70	F♯/G♭6	1479.98
71	G6	1567.98
72	G♯/A♭6	1661.22
73	A6	1760.00
74	A♯/B♭6	1864.66
75	B6	1975.53
76	C7	2093.00
77	C♯/D♭7	2217.46
78	D7	2349.32
79	D♯/E♭7	2489.02
80	E7	2637.02
81	F7	2793.83
82	F♯/G♭7	2959.96
83	G7	3135.96
84	G♯/A♭7	3322.44
85	A7	3520.00
86	A♯/B♭7	3729.31
87	B7	3951.07
88	C8	4186.01

How to read black-key names

Each black key normally has two enharmonic names. The key between C and D can be written C♯, meaning C raised by one semitone, or D♭, meaning D lowered by one semitone. On an equal-tempered piano, both names operate the same key and have the same frequency; the musical key and harmony determine the appropriate spelling.

How Are Piano Note Frequencies Calculated?

Piano frequencies are calculated with a constant ratio between adjacent keys. If n is the piano key number, the equal-tempered formula is:

[
f(n)=440 \times 2^{(n-49)/12}
]

Key 49 is A4 at 440 Hz. The exponent measures how many semitones the chosen key lies above or below A4.

Worked example: calculating middle C

Middle C is key 40, nine semitones below A4:

[
f(40)=440 \times 2^{(40-49)/12}
]

[
f(40)=440 \times 2^{-9/12}\approx261.63\text{ Hz}
]

That result matches the commonly cited frequency of middle C. The formula uses a ratio rather than adding a fixed number because musical intervals are proportional. One semitone multiplies frequency by (2^{1/12}), approximately 1.05946.

Why octaves double frequency

Twelve semitones produce a ratio of (2^{12/12}=2). A3 is 220 Hz, A4 is 440 Hz, and A5 is 880 Hz. The notes share the same pitch class but occupy different registers. This octave relationship guide gives more examples of frequency doubling and halving.

Why Might a Real Piano Differ From the Chart?

A real acoustic piano may not match the table exactly because professional tuners often use stretch tuning. High notes are tuned slightly sharper and low notes slightly flatter than the mathematical targets so the instrument’s octaves sound more aligned.

Inharmonicity and stretched tuning

Ideal strings have harmonics at exact whole-number multiples of their fundamental. Real piano strings are stiff, so their upper partials run slightly sharp. This inharmonicity is strongest in short, thick bass strings and influences how a tuner spaces the octaves.

The amount of stretch varies with piano design, string scale, and the individual instrument. Temperature, humidity, string condition, and the chosen concert-pitch standard can also change measured results. The chart is therefore a mathematical reference, not a record of every properly tuned piano.

Does Each Piano Key Produce Only One Frequency?

A piano key produces a fundamental frequency plus many partials. The chart lists the fundamental—the frequency most closely associated with the note name—but the hammer strike, strings, soundboard, cabinet, and room all shape a much wider spectrum.

Fundamental frequency, partials, and timbre

C4 has a theoretical fundamental of 261.63 Hz, yet its sound also contains energy near higher multiples and non-ideal partial frequencies. Their strengths change as the note begins, sustains, and decays. That changing spectrum gives the piano its recognizable timbre.

An acoustic piano and a digital piano can therefore play the same named note at the same fundamental frequency while sounding different. Frequency identifies pitch; it does not fully describe tone color, loudness, attack, or decay. The distinction is clearer in this comparison of pitch and frequency.

How Can Piano Frequencies Be Used in Practice?

Piano frequency values help with tuning checks, sound analysis, synthesis, and identifying notes in recordings. Match the measured fundamental to both the nearest note and the correct octave; 130.81 Hz is C3, while 261.63 Hz is C4.

Checking a piano or audio signal

A tuner or spectrum display may fluctuate because real notes contain several partials and decay over time. Play one key at a moderate level, allow the initial hammer noise to pass, and compare the stable reading with the chart. A browser-based measurement is an estimate and depends on microphone quality, background noise, and whether the software locks onto the fundamental or a harmonic.

Some MIDI programs label middle C differently even though its frequency remains 261.63 Hz. When software shows C3 instead of C4 for middle C, verify the vendor’s octave convention rather than assuming the audio is transposed. For the measurement unit itself, see how hertz works in music.

Frequently Asked Questions

What frequency is middle C on a piano?

Middle C, or C4 in scientific pitch notation, has a theoretical frequency of approximately 261.63 Hz when A4 is tuned to 440 Hz. It is key 40 on a standard 88-key piano.

What are the lowest and highest frequencies on an 88-key piano?

The lowest key is A0 at 27.50 Hz, and the highest is C8 at approximately 4186.01 Hz under A4 = 440 Hz equal temperament. Acoustic stretch tuning can move the actual measured pitches slightly.

Why does each piano octave double in frequency?

An octave has a 2:1 frequency ratio. Moving 12 equal-tempered semitones upward multiplies the starting frequency by two; moving downward divides it by two.

Are C-sharp and D-flat the same frequency on a piano?

Yes. On a standard equal-tempered piano, C♯ and D♭ are enharmonic names for the same key and frequency. The correct written name depends on the note’s harmonic and melodic role.

Why might a tuned acoustic piano differ from a frequency chart?

Piano tuners stretch octaves to account for string inharmonicity, commonly making upper notes slightly sharper and lower notes slightly flatter than theoretical values. Instrument design, environment, and tuning reference also affect measurements.

Does pressing a piano key produce only its fundamental frequency?

No. A piano key produces a fundamental plus numerous partials, along with mechanical and room resonances. The frequency chart names the fundamental pitch, not the complete sound spectrum.