Piano Reference Pitch Standards

Compare six A4 references and open the 88-key pitch checker with the selected standard.

These are reference pitches, not alternate note layouts. Changing A4 shifts all 88 equal-temperament targets proportionally. It does not model an acoustic piano's instrument-specific octave stretch.

Standard A440

A4 = 440 Hz

88 keys

The ISO standard tuning frequency and the usual reference for modern pianos.

Use A440 unless an ensemble, recording, or technician specifies another reference.

Baroque A415

A4 = 415 Hz

88 keys

A modern reference convention for many historically informed Baroque ensembles.

A415 is about one equal-tempered semitone below A440. Historical pitch varied by place and period.

Concert A442

A4 = 442 Hz

88 keys

A slightly higher reference used by some orchestras and concert settings.

A442 is about 7.85 cents above A440. Confirm the exact reference with the ensemble before a performance.

Classical A432

A4 = 432 Hz

88 keys

An alternative modern reference pitch, eight hertz below A440.

A432 is not the ISO standard. Descriptions of its sound are subjective and do not establish health effects.

French A435

A4 = 435 Hz

88 keys

The historical French diapason normal reference established in 1859.

A435 is useful when studying historical pitch and period performance practice.

Chorton A466

A4 = 466 Hz

88 keys

An approximate high historical organ and church pitch reference.

Chorton was not one universal number; A466 is a practical modern approximation for comparison.