A = 440 Hz or 442 Hz: what it means and which to use
Two musicians who are each perfectly in tune can still clash if one tunes to 440 and the other to 442. This guide explains the reference pitch and how to choose it.
What is the reference pitch
Tuning means comparing your note with a reference. By convention we use the A in the fourth octave (A4, the A above middle C) and measure it in hertz (Hz), vibrations per second. The current international standard (ISO 16) sets A4 = 440 Hz. All other notes are derived with equal temperament, where each semitone multiplies the frequency by the twelfth root of 2 (about 1.0595).
How far apart are 442 and 440
The unit for measuring tuning differences is the cent: a semitone is 100 cents. The formula is 1200 × log₂(f / 440).
| A (Hz) | Difference from 440 | Where it is used |
|---|---|---|
| 415 | −101 ¢ (a semitone lower) | Baroque music on period instruments |
| 430 | −40 ¢ | Rough reference for classical-era music on period instruments |
| 432 | −32 ¢ | Favoured by some; no demonstrated musical advantage |
| 440 | 0 | International standard, bands, schools, most tuners |
| 442 | +7.9 ¢ | Many professional orchestras |
| 443 | +11.8 ¢ | Some European orchestras |
Eight cents (440 versus 442) is a small but audible difference when two instruments play the same note: you get a beat, a slow pulsing in volume. The beat rate equals the difference between the two frequencies, so 440 and 442 Hz produce 2 beats per second.
Why orchestras raise the pitch
Over history the pitch has tended to rise, because a slightly higher sound seems brighter. Documents from 17th and 18th-century Europe show very different pitches by city and period (see the history of pitch). Today many professional orchestras tune above 440, between 442 and 443 Hz, but there is no rule: each orchestra decides.
What about 432 Hz
Claims about special effects of A at 432 Hz circulate online. There is no serious evidence that this pitch is more “natural” or healthy. It is a possible tuning with its own history (see the table), and if your ensemble picks it, that is an aesthetic decision, not a musical truth.
How to agree in an ensemble
- Ask what the group's A is. A band or choir usually uses 440; an orchestra, 442 or 443.
- Everyone tunes to the same source (a piano, an oboe, a tuner or a drone), not each to their own tuner set to a different A.
- With a tuned piano, the piano's A rules. A piano cannot be adjusted on the spot, so the others adapt.
- Set your tuner to the same A. In the Atril tuner you change the reference A under ⚙.
How the pitch changes on your instrument
On wind instruments you adjust by lengthening or shortening the tube: the tuning slide on brass, the barrel on flute and clarinet. Pulling out lowers the pitch, pushing in raises it. A 2 Hz difference is usually a matter of a few millimetres, but after adjusting you must recheck the other notes, because every instrument has its own tendencies.
Open the tuner Drone (reference A)
More data and sources: History of pitch and tempo. Next: how to tune well.
Frequently asked questions
Which A should I use when practising alone?
440 Hz: it is the standard and what almost every tuner, app and backing track uses. If you join an orchestra that tunes higher, adjust when asked.
Can you hear the difference between 440 and 442?
Yes, when they sound together: 2 Hz apart gives 2 beats per second, heard as a pulse. On its own it is hard to notice without comparing.
What is the difference between a tuning fork and a tuner?
A tuning fork produces one fixed note (normally A 440). An electronic tuner measures the note you play and shows how far you are from the reference you choose.