Baroque A415 quick reference
- A4 reference
- 415 Hz
- Relative to A440
- -101.3 cents
- Meter range
- A0–C8
What this reference means
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.
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 | 25.94 Hz |
| 40 | C4 | 60 | 246.76 Hz |
| 49 | A4 | 69 | 415.00 Hz |
| 52 | C5 | 72 | 493.52 Hz |
| 88 | C8 | 108 | 3948.17 Hz |
Need every key? Open the interactive 88-key frequency chart.
Instrument safety and scope
Do not lower an acoustic piano from A440 without discussing the tension change with a piano technician.
Method and sources
Each displayed target uses frequency = 415 × 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.
Baroque A415 FAQ
What does Baroque A415 mean?
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.
Does this page really use A4 = 415 Hz?
Yes. Every key target is recalculated from A4 = 415 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 415 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.