Chorton A466 quick reference
- A4 reference
- 466 Hz
- Relative to A440
- +99.4 cents
- Meter range
- A0–C8
What this reference means
An approximate high historical organ and church pitch reference.
Chorton was not one universal number; A466 is a practical modern approximation for comparison.
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 | 29.13 Hz |
| 40 | C4 | 60 | 277.09 Hz |
| 49 | A4 | 69 | 466.00 Hz |
| 52 | C5 | 72 | 554.17 Hz |
| 88 | C8 | 108 | 4433.36 Hz |
Need every key? Open the interactive 88-key frequency chart.
Instrument safety and scope
Do not raise a modern acoustic piano to A466. The large tension change can damage strings or the instrument.
Method and sources
Each displayed target uses frequency = 466 × 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.
Chorton A466 FAQ
What does Chorton A466 mean?
An approximate high historical organ and church pitch reference. Chorton was not one universal number; A466 is a practical modern approximation for comparison.
Does this page really use A4 = 466 Hz?
Yes. Every key target is recalculated from A4 = 466 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 466 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.