What is 440 Hz?
440 Hz is the international standard pitch for the note A above middle C (A4). It is the reference that most orchestras, tuners, and digital instruments use, which makes it the most useful single tone to have on hand when tuning an instrument or checking pitch.
Before the standard was adopted, tuning varied widely between regions, time periods, and even individual ensembles. Today, 440 Hz gives musicians a common starting point, even though some listeners prefer alternative tunings such as 432 Hz for their own reasons.
In practical terms, if you play a string instrument, a wind instrument, or sing in a group, the ability to generate a clean 440 Hz reference is genuinely valuable. It is the note you check against time and again, and an unreliable reference can throw an entire section off-key.
How to use this 440 Hz generator
Press Play to start a steady 440 Hz sine tone. A pure sine wave is usually the easiest reference to match when tuning a string or wind instrument, because it is clean and contains only the fundamental pitch with no confusing overtones.
Adjust the volume so the tone is clear but not louder than your instrument — you want to hear both together, not drown out the string you are tuning. Start with a low volume and raise it only as needed.
If you need a brighter timbre for a different listening test, switch to triangle or sawtooth. The download controls let you export a short WAV file for use in other projects or for keeping an offline reference on a phone.
The tone auto-stops after 60 seconds, and you can press Stop at any time.
Why 440 Hz matters
Because nearly every commercial instrument and tuner defaults to 440 Hz, knowing this pitch is practically useful. Ensembles check it before playing, and a misplaced reference can throw an entire group off-key before a note is even played.
This page gives you an instant, free reference tone without a metronome app or tuner, on any device. Keep it open while you tune, and you can generate a fresh 440 Hz tone whenever you need to check a string again.