440 Hz tone
Concert A itself — the pitch the musical world agrees on.
440 Hz
Stopped
Nearest note: A4 · exactly in tune (440 Hz)
The most agreed-upon pitch on Earth
When an orchestra tunes, the oboe sounds A4 and every section matches it — that note is 440 Hz, standardized internationally (ISO 16) in the 1950s after decades of competing pitches. This player produces it with zero cents deviation: not near A, but A itself, the reference against which tuners, keyboards, and broadcast tones are calibrated.
Its fingerprints are everywhere in daily life. The classic North American telephone dial tone blends 350 Hz with 440 Hz, guitar tuners default to it, and music-theory examples use it as the anchor for explaining octaves and cents. If you learn only one frequency by heart, this is the one.
Tuning and testing with concert A
To tune, play the tone at a moderate level and adjust your instrument until the wavering beats between the two sources slow to a standstill — stillness means match. Wind players should warm up first, since cold instruments read flat, and guitarists should check intonation at the twelfth fret as well as the open string.
Studios treat 440 Hz as the daily sanity check: play it through a new interface or monitor controller and confirm meters, tuners, and your ears all agree before a session starts. A mismatch caught here saves hours of mysteriously out-of-tune overdubs later.
As a midrange test signal, 440 Hz sits where ears are sensitive and speakers are honest, so left-right comparisons here expose real imbalances. Pair it with the 432 Hz tone to train your ear on flat-versus-standard color, or stack it in the multi tone generator to build beats and chords from a known-good root.
More frequencies
Frequently asked questions
Why is 440 Hz the standard tuning pitch?
International conferences settled on A4 = 440 Hz to end decades of incompatible orchestra pitches, and ISO 16 formalized it in the 1950s. One shared reference lets instruments built in different countries play together, and tuner makers, broadcasters, and educators all calibrate to it.
How do I tune my guitar to 440 Hz?
Play this tone, match your high E string fifth-fret harmonic region by ear, or tune the A string fifth fret area against it and work outward. Listen for beats — the pulsing clash between slightly different pitches — and tighten or loosen until the pulsing stops completely.
Where else does 440 Hz appear?
The North American dial tone mixes 350 and 440 Hz, electronic tuners beep it as their default, and countless ear-training recordings use it as the starting reference. Whenever a device needs one trustworthy pitch, concert A is the usual choice.