Classical A432 quick reference
- A4 reference
- 432 Hz
- Relative to A440
- -31.8 cents
- Meter range
- A0–C8
What this reference means
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.
Sample calculated key targets
The meter applies the same formula to all 88 keys. These sample values make the selected reference visible before microphone use.
| Piano key | Note | MIDI | Frequency |
|---|---|---|---|
| 1 | A0 | 21 | 27.00 Hz |
| 40 | C4 | 60 | 256.87 Hz |
| 49 | A4 | 69 | 432.00 Hz |
| 52 | C5 | 72 | 513.74 Hz |
| 88 | C8 | 108 | 4109.90 Hz |
Need every key? Open the interactive 88-key frequency chart.
Instrument safety and scope
Use this page to measure or compare pitch, not as instructions for retensioning an acoustic piano.
Method and sources
Each displayed target uses frequency = 432 × 2((MIDI − 69) / 12). This is a transparent equal-temperament calculation. A real piano's string inharmonicity leads technicians to stretch octaves, so a browser target is not a complete tuning curve.
Classical A432 FAQ
What does Classical A432 mean?
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.
Does this page really use A4 = 432 Hz?
Yes. Every key target is recalculated from A4 = 432 Hz using the 12-tone equal-temperament formula. The selected reference changes both automatic note matching and fixed-key targets.
Can I retune an acoustic piano to 432 Hz with this page?
This page can measure and compare pitch, but it cannot assess the instrument's structure, unisons, stretch, or stability. Ask a qualified piano technician before changing an acoustic piano's overall pitch.