Tone generator

Any frequency from 1 Hz to 22 kHz. Four waveforms, left or right channel, keyboard control, and a WAV of exactly what you hear.

Silent
Left Right
Hz

Keyboard: space plays and stops, arrow keys step the frequency (hold shift for ten at a time), and the letter keys A to K play a scale from C4.

A frequency generator that does the three awkward things

Most online tone generators will play you a sine wave. Fewer will send it to one ear only, almost none let you drive it from the keyboard while your hands are busy holding a speaker cabinet, and hardly any will hand you the tone as a file afterwards. This one does all three, because those are the moments when a browser tool usually sends you looking for an app.

The frequency slider is logarithmic, which matters more than it sounds. Pitch is perceived in octaves, so on a linear slider every useful bass frequency is crushed into the first few pixels and the remaining nine tenths of the track is treble. On a logarithmic track an octave takes the same travel wherever you are, and 40 Hz is as easy to land on as 4 kHz.

Reading the note and cents display

Beside the frequency you get the nearest note and how far the current frequency sits from it, in cents. A cent is one hundredth of a semitone; a difference of about five cents is the point where most people stop hearing a mistuning on a sustained note. Concert A at 440 Hz reads as A4 exactly, and the alternative 432 Hz tuning reads as A4 about 32 cents flat, which is the honest way to describe it — a third of a semitone below standard pitch, not a different note.

What each waveform is good for

A sine wave is a single frequency with no harmonics. Use it for anything where you care about the number: hearing tests, channel checks, speaker response, tuning. A square wave contains every odd harmonic and is much louder for the same amplitude, which makes it the fastest way to find a buzz in a cabinet, a loose grille or a trim panel in a car. A sawtooth contains every harmonic and is the classic synthesiser sound, useful for hearing distortion in an amplifier. A triangle sits between a sine and a square: a little brighter than a sine, far gentler than a square.

Common frequencies and what they are for

FrequencyUsually used for
20–30 HzChecking whether a subwoofer produces anything at the very bottom
40–60 HzSubwoofer level matching, finding rattles in furniture and panels
50 or 60 HzRecognising mains hum — 50 Hz in most of the world, 60 Hz in North America
440 HzConcert pitch, and a safe all-purpose test tone
1 kHzThe reference frequency for comparing levels between systems
3–4 kHzWhere the ear is most sensitive; a good check for harshness
8–12 kHzConfirming the tweeter or the top end of a headphone is working
17–19 kHzThe "mosquito" range, audible mostly to younger listeners

The frequency bands underneath

Every frequency you can set here falls into one of seven bands, and knowing which one you are in explains most surprises — particularly why a tone you can see on the trace produces no sound from a laptop.

  • Sub-bass (20 Hz–60 Hz): Felt more than heard. Most laptop and phone speakers produce nothing here.
  • Bass (60 Hz–250 Hz): Kick drum and bass guitar. A small speaker usually starts somewhere in this band.
  • Low mids (250 Hz–500 Hz): Body and warmth. Too much here sounds boxy.
  • Mids (500 Hz–2 kHz): Where most of a voice lives. Every speaker reproduces this band.
  • Upper mids (2 kHz–6 kHz): Consonants and presence. The ear is most sensitive around 3 kHz.
  • Treble (6 kHz–12 kHz): Cymbals and air. Cheap earbuds often roll off before the top of this band.
  • Top end (12 kHz–22 kHz): Hearing here narrows with age, and most music carries little of it.

Exporting a WAV

The download gives you a five-second 16-bit stereo WAV at your device's sample rate, with a ten millisecond fade at each end so it starts and stops silently rather than clicking. Channel routing is preserved, so a left-only tone stays left-only wherever you play it back. Because it is a real file, you can loop it in an editor, load it onto a phone for testing a car system, or drop it into a video as a reference tone.

If you need a whole test sequence rather than one tone, the sound test runs the five standard checks in order, and the bass test and hearing range test sweep the two ends of the spectrum for you.

Frequently asked questions

What is an online tone generator?

It is a page that produces a single audio frequency on demand instead of playing a recording. The browser calculates the waveform sample by sample, so the tone is exact, starts instantly and can be any frequency you type rather than one of a fixed set of files.

What frequency range does it cover?

One hertz to 22,000 Hz. Below about 20 Hz you will feel a large speaker moving rather than hear a pitch, and above roughly 17 kHz most adults hear nothing at all even though the signal is still there.

Can I play a tone in one ear only?

Yes. Set Output to left or right. The signal is routed through separate gain stages into a two-channel merger, so a left-only tone is true silence on the right rather than a quiet version of the same sound.

Can I download the tone as a file?

Yes. The download button renders exactly what is on screen — frequency, waveform and channel — as a five-second 16-bit stereo WAV, faded at both ends so it does not click. The file is built in your browser; nothing is uploaded or requested from a server.

How do I use the keyboard?

Space starts and stops the tone. The up and down arrows move the frequency one hertz at a time, or ten with shift held. The letters A through K play a C major scale from C4 to C5, which is enough to check an instrument against concert pitch.

Which waveform should I use?

A sine wave for anything involving measurement or hearing, because it contains one frequency and nothing else. A square or sawtooth wave contains harmonics all the way up, which makes it louder, harsher and much better at revealing a rattle in a speaker cabinet or a panel in a car door.

What is 440 Hz used for?

It is concert pitch, the A above middle C, and the reference most instruments are tuned to. It is also a convenient general-purpose test tone because every speaker reproduces it easily.

Why does a low tone sound quiet?

Two reasons at once. Human hearing is far less sensitive below about 200 Hz, so an equally powerful tone genuinely sounds quieter; and most small speakers produce very little down there to begin with. Do not compensate by raising the volume a long way, because the power reaching the driver is real even when the perceived loudness is not.

Is a tone generator safe for my speakers?

At moderate volume, yes. Risk comes from sustained high-output tones, particularly square waves into tweeters and very low frequencies into small drivers. Keep the volume at a level where nothing distorts or rattles, and do not leave a loud tone running unattended.

Can I use this to tune an instrument?

For a rough tuning, yes — play the note, match it by ear, and watch for the beating between the two pitches slowing down as you get closer. The readout shows the nearest note and how many cents away the current frequency is, so you can also set a deliberately flat or sharp reference such as 432 Hz.

Does it work on a phone?

Yes, including the WAV download on both iOS and Android. On a phone the output is a small speaker with almost no low-frequency response, so anything below about 300 Hz will be faint or inaudible regardless of the volume.

Why does my tone sound rough or buzzy at high frequencies?

If you are using a square or sawtooth wave, the harmonics above the fundamental fold back down as aliasing at high frequencies, which sounds gritty. Switch to a sine wave, which has no harmonics to fold.

Does the page record any audio?

No. It never requests microphone access and it has nothing to record with. Everything happens in the audio output path of your own browser.

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