Tone generator
The tone generator plays any frequency from 1 to 20,000 Hz as a sine, square, sawtooth or triangle wave. No install needed; start with the volume low.
In hertz, from 1 to 20,000. The up and down arrow keys change it by 1 Hz, Page Up and Page Down by one octave.
Start quiet and turn up slowly. Loud tones can damage your hearing and your speakers, and very high ones can be loud before you notice them.
Runs in your browser. Test data stays on your device.
- Nearest note
- A4In tune · note at 440 Hz
Presets
Frequency sweep
The pitch moves evenly, octave by octave. At the end the tone fades out and the frequency goes back to the start. Changing the frequency or stopping the tone ends the sweep early.
- Period
- 2.27msWavelength in air: 78 cm
How to use the tone generator
- Turn your speakers or headphones down first.
- Set the frequency: type it in hertz and press Enter, drag the slider, use the −1 Hz, +1 Hz, −1 oct. and +1 oct. buttons, or pick a preset.
- Choose a waveform: Sine, Square, Sawtooth or Triangle.
- Press Play tone, then raise the volume slowly, first with the Volume slider and then, if needed, on your device.
- Press Stop tone when you are done. Copy link copies the tone together with a link that reopens the same frequency and waveform.
In the frequency field, the up and down arrow keys change the frequency by 1 Hz, and Page Up and Page Down by one octave. An octave up doubles the frequency, and an octave down halves it. The slider is logarithmic, so every octave has the same width. A shared link only sets the controls: sound starts when you press Play tone.
Presets and readouts
The tool shows the frequency, the nearest musical note, and the period and wavelength of the tone.
| Result | What it means | What to do |
|---|---|---|
| 20 Hz | The low end of hearing. Laptop, phone and small desktop speakers cannot play it, so silence there is normal. | Try headphones or a subwoofer. Below 20 Hz you feel a sine more than you hear it, and the other waves are heard only as clicks. |
| 50 Hz and 60 Hz | The AC power (mains) frequency: 50 Hz in Europe and most of the world, 60 Hz in North America and parts of South America and Asia. | Play the one for your country to learn what a power hum sounds like. |
| 100 Hz | Bass. Laptop and phone speakers play tones under about 100 to 200 Hz weakly or not at all. | If it is faint, raise the frequency until the tone gets clearly louder. That is roughly where your speakers start to play. |
| 440 Hz | A4, the tuning pitch, and the tone the page starts with. | Tune an instrument to it by ear. The cents readout shows how far a frequency is from the nearest note. |
| 1 kHz (1,000 Hz) | The usual reference tone for audio checks. | Move Balance fully left, then fully right, to check that each channel plays on its own side. |
| 10 kHz | High treble. The tone sounds thin and sharp. | Keep the volume low: very high tones can be loud before you notice them. |
| 15 kHz | Very high. Many adults hear it weakly or not at all. | Do not turn the volume up to hear it. The tool is not a hearing test. |
Waveform is the shape of the sound wave. A sine has one frequency and sounds pure. A square wave adds the odd multiples of that frequency (3×, 5×, 7× and so on), a sawtooth adds all multiples, and a triangle adds odd multiples that fade quickly, so it sounds softer than a square. The extra frequencies make the sound brighter. The generator lowers a square, sawtooth or triangle wave where it would sound louder than a sine at the same Volume setting, so switching shape should not make the tone jump.
Nearest note is the musical note closest to the tone in equal temperament, with A4 at 440 Hz. Cents show the distance from that note: a semitone is 100 cents, and the readout runs from 50 cents flat to 50 cents sharp. A difference of a few cents is hard to hear.
Period is how long one cycle lasts, 2.27 ms at 440 Hz. Wavelength in air is how long one cycle is, 78 cm at 440 Hz and 3.43 m at 100 Hz. Bass tones have wavelengths of several meters, which is why a room can boom at some frequencies.
Sweep glides the pitch from the From value to the To value over the chosen Duration of 5, 10, 20, 30 or 60 seconds, and starts with 20 Hz to 20,000 Hz over 10 seconds. Every octave takes the same time, which matches how pitch is heard; the default range covers about ten octaves, around one second each. Start sweep also starts the tone if it is silent. Stop sweep freezes the pitch and the tone keeps playing. At the end of a sweep the tone fades out and stops, and the frequency goes back to the start.
Tone generator not working?
The tone generator asks for no permission, so it has few ways to fail. When it cannot start, it shows a message in place of the display.
Your browser does not support this test
The browser has no Web Audio API, which the tone generator needs to make sound. Update the browser or open the page in Chrome, Edge, Firefox or Safari.
Something went wrong
The browser refused to start the sound, or the page could not build it. Browsers play sound only after a click or a key press, so press Play tone again. If it keeps happening, reload the page or try another browser.
It says Playing, but there is no sound
- Volume: the Volume slider starts at 25%. Raise it, then your system volume, then the volume on the speakers or headphones.
- Output device: check that the sound goes where you expect. On Windows, click the speaker icon in the taskbar and choose the output. On a Mac, open System Settings > Sound > Output. Bluetooth headphones may be connected to another device.
- Muted tab: a muted tab shows a crossed-out speaker icon. Click it to unmute.
- Balance: keep it in the middle. Fully left or fully right, only one channel plays.
- iPhone and iPad: the page asks iOS to play the tone like music, which lets current Safari play it even when the phone is set to silent. If you hear nothing, check the silent mode and the volume, or use headphones.
- Very low or very high tones: small speakers do not play tones under about 100 to 200 Hz, and many cannot play the highest ones. Try 1,000 Hz, which almost any speaker plays.
The tone stops by itself
The tone stops when the page is hidden, for example when you switch to another tab, and when the system takes the audio away, such as during a call on a phone or when another app starts playing. The page then goes back to Play tone, so press it again. A sweep also ends with a stopped tone, and the frequency goes back to the start.
The sound crackles, distorts or rattles
The tone generator cannot hear what your speakers do with the sound. Distortion at high volume usually means the speakers or the amplifier have reached their limit, so turn it down. Square and sawtooth waves carry strong high harmonics and sound harsher, so try a sine first. A rattle at one pitch is a loose part, a cable or a panel: use the sweep, and press Stop sweep where the rattle starts.
How we measure
The tone generator makes the sound in your browser with the Web Audio API: one oscillator, set to a sine, square, sawtooth or triangle wave at your frequency, passes through a volume stage and a stereo balance stage to your output device. The Volume slider follows a squared curve, so its 25% starting point plays about 24 dB below full scale for a sine, and the square, sawtooth and triangle waves are lowered where they would sound louder than a sine at the same setting. The nearest note uses equal temperament with A4 at 440 Hz, and the wavelength assumes sound traveling at 343 m/s (air at 20 °C). A browser cannot measure what leaves your speakers, so the tool shows the frequency it asks for and no loudness in decibels, and the sound card and the speakers decide how faithfully it is played.
Frequently asked questions
How loud should I play a test tone?
Quietly. Turn the volume down before you press Play tone, then raise it slowly until you can hear the tone clearly, and no further. The Volume slider starts at 25%, and very high tones can be loud before you notice them. Loud tones, especially long ones, can damage your hearing and your speakers.
Why can’t I hear the highest tones?
Many adults hear little or nothing above about 15,000 Hz, and many speakers play such tones weakly, so a faint result is common. What you hear depends on your ears, your speakers and the volume. The tone generator is not a hearing test, so do not raise the volume to force a tone through.
What are the 50 Hz and 60 Hz tones for?
They are the AC power (mains) frequency, 50 Hz in Europe and most of the world and 60 Hz in North America and parts of South America and Asia. Playing the one for your country shows what a hum from power wiring sounds like. Such a hum often comes from a ground loop or from a cable laid next to a power line.
How can I find where my speakers start to play?
Use the sweep. Keep the defaults, 20 to 20,000 Hz over 10 seconds, turn the volume down and press Start sweep. Press Stop sweep the moment you first hear the tone, and the pitch freezes with its frequency on screen. Do the same where it fades at the top. It is done by ear, so treat the result as an estimate.
Can I tune an instrument with the tone generator?
Yes, as a reference tone. Play the frequency of the note you want, such as 440 Hz for A4 or 110 Hz for the A string of a guitar, and tune the instrument by ear until the two sound steady together. The tool does not listen to your instrument, so it cannot tell you whether you are in tune.
Does the sound leave my device?
No. Your browser makes the tone on your device and plays it to your speakers or headphones. The tool uses no microphone and records nothing. Your frequency and waveform are written after the # in the page address so that Copy link can reopen them.