Note Frequencies: All 88 Piano Keys in Hz, MIDI and Wavelength

Piano key frequencies
Key	MIDI	Frequency (Hz)	Period (ms)	Wavelength (cm)
1	21	27.500	36.364	1247.3
2	22	29.135	34.323	1177.3
3	23	30.868	32.396	1111.2
4	24	32.703	30.578	1048.8
5	25	34.648	28.862	990.0
6	26	36.708	27.242	934.4
7	27	38.891	25.713	882.0
8	28	41.203	24.270	832.5
9	29	43.654	22.908	785.7
10	30	46.249	21.622	741.6
11	31	48.999	20.408	700.0
12	32	51.913	19.263	660.7
13	33	55.000	18.182	623.6
14	34	58.270	17.161	588.6
15	35	61.735	16.198	555.6
16	36	65.406	15.289	524.4
17	37	69.296	14.431	495.0
18	38	73.416	13.621	467.2
19	39	77.782	12.856	441.0
20	40	82.407	12.135	416.2
21	41	87.307	11.454	392.9
22	42	92.499	10.811	370.8
23	43	97.999	10.204	350.0
24	44	103.83	9.631	330.4
25	45	110.00	9.091	311.8
26	46	116.54	8.581	294.3
27	47	123.47	8.099	277.8
28	48	130.81	7.645	262.2
29	49	138.59	7.215	247.5
30	50	146.83	6.810	233.6
31	51	155.56	6.428	220.5
32	52	164.81	6.067	208.1
33	53	174.61	5.727	196.4
34	54	185.00	5.405	185.4
35	55	196.00	5.102	175.0
36	56	207.65	4.816	165.2
37	57	220.00	4.545	155.9
38	58	233.08	4.290	147.2
39	59	246.94	4.050	138.9
40	60	261.63	3.822	131.1
41	61	277.18	3.608	123.7
42	62	293.66	3.405	116.8
43	63	311.13	3.214	110.2
44	64	329.63	3.034	104.1
45	65	349.23	2.863	98.2
46	66	369.99	2.703	92.7
47	67	392.00	2.551	87.5
48	68	415.30	2.408	82.6
49	69	440.00	2.273	78.0
50	70	466.16	2.145	73.6
51	71	493.88	2.025	69.4
52	72	523.25	1.911	65.6
53	73	554.37	1.804	61.9
54	74	587.33	1.703	58.4
55	75	622.25	1.607	55.1
56	76	659.26	1.517	52.0
57	77	698.46	1.432	49.1
58	78	739.99	1.351	46.4
59	79	783.99	1.276	43.8
60	80	830.61	1.204	41.3
61	81	880.00	1.136	39.0
62	82	932.33	1.073	36.8
63	83	987.77	1.012	34.7
64	84	1046.50	0.956	32.8
65	85	1108.73	0.902	30.9
66	86	1174.66	0.851	29.2
67	87	1244.51	0.804	27.6
68	88	1318.51	0.758	26.0
69	89	1396.91	0.716	24.6
70	90	1479.98	0.676	23.2
71	91	1567.98	0.638	21.9
72	92	1661.22	0.602	20.6
73	93	1760.00	0.568	19.5
74	94	1864.66	0.536	18.4
75	95	1975.53	0.506	17.4
76	96	2093.00	0.478	16.4
77	97	2217.46	0.451	15.5
78	98	2349.32	0.426	14.6
79	99	2489.02	0.402	13.8
80	100	2637.02	0.379	13.0
81	101	2793.83	0.358	12.3
82	102	2959.96	0.338	11.6
83	103	3135.96	0.319	10.9
84	104	3322.44	0.301	10.3
85	105	3520.00	0.284	9.7
86	106	3729.31	0.268	9.2
87	107	3951.07	0.253	8.7
88	108	4186.01	0.239	8.2

The formula

Equal temperament divides each octave into twelve equal ratios, so a note n semitones above A4 has frequency f = 440 × 2^n/12. With MIDI numbers, f = 440 × 2^{(m − 69)/12}. Period is 1000 / f in milliseconds; wavelength is the speed of sound divided by f. The table updates when you change the reference pitch above.

For the cents between two frequencies, use 1200 × log₂(f₂ / f₁); the cents article works through examples, and the tuner shows it live.

Questions

What is the frequency of middle C?

Middle C, C4, is 261.63 Hz when A4 is tuned to 440 Hz. It is MIDI note 60 and the fortieth key of an 88-key piano.

What frequency is A4?

A4 is 440 Hz in modern concert pitch, MIDI note 69. Some orchestras tune a little higher, 442 to 445 Hz, and period-instrument groups often use 415 Hz.

How do you calculate the frequency of a note?

f = 440 × 2^((n − 69) / 12), where n is the MIDI note number. Each semitone multiplies the frequency by the twelfth root of two, about 1.0595, and each octave doubles it.

What are the lowest and highest piano notes?

The lowest key, A0, is 27.5 Hz (MIDI 21). The highest, C8, is 4186.01 Hz (MIDI 108). Together they span a little over seven octaves.

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Note frequencies

The formula

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