1Standard A440 Tuning (C3 to C5)
Inputs
Result
Two octaves from C3 (130.81 Hz) to C5 (523.25 Hz) with 25 notes including both endpoints.
Notes
25
A4
440 Hz
Offset
0 cents
Equal Temperament
25
notes in range
A4 Ref
440 Hz
Cents Offset
0
Inputs
Result
Two octaves from C3 (130.81 Hz) to C5 (523.25 Hz) with 25 notes including both endpoints.
Inputs
Result
Same range at A415: C3 = 123.47 Hz, A4 = 415 Hz, offset of -101 cents from standard.
Equal temperament divides the octave into 12 equal semitones, each with a frequency ratio of 2^(1/12) = 1.05946. This means every key is equally in tune (or equally out of tune) with every other key, allowing free modulation.
| Temperament | Advantage | Disadvantage | Used In |
|---|---|---|---|
| Equal | All keys usable | No pure intervals | Modern piano, guitar |
| Just Intonation | Pure intervals in one key | Out of tune in others | Choral singing, some organs |
| Meantone | Good thirds in some keys | Wolf fifth in remote keys | Historical keyboards |
A432 Hz is claimed to sound warmer and more natural. There is no scientific basis for specific healing properties, but the lower pitch does create a slightly different tonal color. Standard concert pitch A440 was internationally standardized in 1955.
A standard piano has 88 keys spanning from A0 (27.5 Hz) to C8 (4186 Hz), covering over 7 octaves. The lowest audible fundamental is A0 at 27.5 Hz, and the highest key C8 approaches the upper limit of useful musical pitch.
A cent is 1/100 of a semitone. There are 1200 cents per octave. Tuners measure deviation from target pitch in cents. Most people cannot hear a difference smaller than 5 cents; professional tuners aim for ±2 cents accuracy.
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Last Updated: Mar 20, 2026
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