This online tone generator plays any frequency from 1 Hz to 20 kHz, decimals included, as a sine, square, triangle or sawtooth wave. Type a value, drag the slider or pick a note: the page shows the nearest note and how many cents away it is.
The sound is generated by your browser itself (Web Audio API), with no file to download, no sign-up and nothing sent to a server.
How to use it
- Type a frequency, drag the slider or tap a preset (60 Hz, 440 Hz, 1 kHz…).
- Tap Play with the volume low and turn it up gradually, especially on headphones.
- Use −1, −0.1, +0.1 and +1 for fine tuning, and ÷2 or ×2 to jump an octave.
- To play a note, choose the note and octave; the Reference A (440, 432, 442…) recalculates every note.
- To test speakers or headphones, pick a channel or use the sweep.
What an online tone generator is for
Tuning by ear: play the string's note (E2, 82.41 Hz, a guitar's low E) and adjust until the beating, the “wah-wah” between the two sounds, stops. Ear training: play a note, sing the fifth above and check it. Speaker and headphone tests: a 20–200 Hz sweep shows where the bass drops out and where something rattles; the channel selector checks each side.
DIY hearing check: sweep from 8 kHz to 20 kHz at low volume and tap Stop when you can no longer hear it. It is a curiosity, not a medical test: it depends on your headphones and the room, and it does not replace a hearing test by an audiologist.
Sine, square, triangle and sawtooth waves
The sine wave is a pure tone, the best for tuning and for testing hearing and speakers. The triangle sounds similar, a little brighter. The square wave has only odd harmonics and sounds hollow, like an old video game; the sawtooth has all of them and sounds buzzy, like a synth. Because those two seem louder, the generator plays them more quietly. Above about 7 kHz all four sound the same: their harmonics are beyond hearing.
What frequency range can humans hear?
The textbook figure is 20 Hz to 20 kHz, but that applies to young people. The upper limit drops with age: teenagers often hear up to 17 or 18 kHz, adults in their 30s and 40s up to 14 to 16 kHz, and people over 50 up to around 12 kHz. It varies a lot from person to person, and many headphones and phones can't reproduce the extremes.
Tips
- To check your headphones, play 1 kHz at low volume and switch between Left and Right: the sound should come from the correct side at the same level.
- Don't turn up the volume to “hunt” for a high tone you can't hear: loud high frequencies tire your ears even when they seem faint.
- Phones barely reproduce anything below 150 to 200 Hz; for real bass, use speakers or a subwoofer.
- For the hearing check, repeat the sweep going down (swap From and To) and compare.
Frequently asked questions
How do I test my subwoofer with a tone generator?
With the volume low, play 60 Hz and turn it up slowly. Then sweep from 20 to 200 Hz over about 30 seconds: where the sound fades out is the speaker's limit, and where something buzzes or rattles is a resonance (a loose screw, panel or grille).
Why can't I hear frequencies above 15 kHz?
It may be age, since the upper limit drops over the years, or your gear: many headphones and speakers stop at 15 or 16 kHz. Try another pair before drawing conclusions.
Is it safe to listen to high-frequency tones?
At low volume and for short periods, yes: keep the level low, especially on headphones, and stop if you feel discomfort or ringing in your ears. Loud steady tones can also damage speakers, and a loud square wave can overheat a tweeter.
What is the frequency of A4?
440 Hz, the international tuning standard. Each octave doubles or halves it: A3 is 220 Hz and A5 is 880 Hz. Many orchestras tune slightly higher, to 442 Hz.
What is 432 Hz tuning?
Tuning A to 432 Hz instead of 440: everything sounds about 32 cents (a third of a semitone) lower. There is no scientific evidence for the healing effects claimed for it. To play notes at 432, change the Reference A.
What are 60 Hz and 1 kHz tones used for?
60 Hz is the mains frequency in North America (50 Hz in the UK, Europe, India and Australia): the ground-loop hum of cables and amps sits there. 1 kHz is audio's reference tone, used to line up levels on mixers and audio interfaces.
There's no sound. What should I do?
Check your media volume, any Bluetooth headphones and, on iPhone, silent mode. Try 440 Hz: very low and very high tones may not come out of a phone speaker. To measure what's playing, open the online tuner on another device.