Free Tone Generator

Worked example

Type 1000 into "Frequency", keep "Sine", leave "Speakers" on "Both", keep Volume at its default 20%, and set "Duration" to 10 s. The big readout shows 1,000 Hz and the line under it reads "B5 +21 c", meaning 21 cents above B5. "Play" sounds a steady tone until you press "Stop"; the duration only applies to files and sweeps. "Download WAV" saves tone-1000hz-sine.wav: mono, 16-bit, 48,000 Hz, 10 seconds, 960,044 bytes (937.5 KB). Because "Louder file: normalise to -1 dBFS (ignores volume)" is ticked by default, the page says "File peak: -1.0 dBFS". Untick it and the line changes to "File peak: -20.0 dBFS", which is what 20% volume means. Switch "Speakers" to "Left only" and the same 10 seconds becomes a stereo file with silence on the right, named tone-1000hz-sine-left.wav, about 1.8 MB.

Which settings to use, and the limits

• Choose a steady tone or a sweep. "Steady tone" plays one frequency until you stop it. "Frequency sweep" glides from "Start frequency" to "End frequency" over the "Duration" and then stops, or repeats if you tick "Repeat sweep". "Logarithmic" spends equal time on each octave, which sounds even; "Linear" spends equal time on each hertz, so most of the time is spent at high pitches. For 20 Hz to 20,000 Hz over 10 seconds, the logarithmic sweep is at about 632 Hz after 5 seconds and the linear one at about 10,000 Hz. The noise waveforms have no sweep.
• Set the pitch exactly, by number or by note. The range is 1 Hz to 22,000 Hz. Use the slider (it is logarithmic), type a number (it is rounded to 0.01 Hz), or step with the -10, -1, -0.1, +0.1, +1 and +10 buttons. A number outside the range is pulled back with the note "Limited to the range 1–22,000 Hz." "Jump to note" lists the 72 notes from C2 to B7, and "A4 =" sets the reference to 440, 432, 415 or 442 Hz. The note line shows the nearest note and how many cents sharp or flat you are. While a steady tone plays, changes to the frequency, waveform and volume apply straight away.
• Use the presets for quick checks. Under "Hearing test" are 1, 4, 8, 12, 15 and 17 kHz. Under "Bass test" are 20, 30, 40, 50, 63 and 100 Hz. Under "Tuning" are E2, A2, D3, G3, B3, E4 and A4, which at A4 = 440 Hz are 82.41, 110, 146.83, 196, 246.94, 329.63 and 440 Hz, and which follow the "A4 =" setting (at 432 Hz, E2 becomes 80.91 Hz). Below 20 Hz you feel the speaker cone move more than you hear a tone. What you hear depends on your speakers or headphones and on your own hearing.
• Start quiet, and choose the speaker side. Volume starts at 20%. In live playback 100% is an amplitude of 0.5 (-6 dBFS) and 20% is -20 dBFS, so the slider only sets a level relative to your device volume. Keep it low with headphones, as the page warns. "Speakers" offers "Both", "Left only", "Right only" and "L then R", which switches side every second and says "Playing in the left channel" or "Playing in the right channel". Changing the side while playing restarts the tone. "Auto-stop" can end playback after 1, 5, 15, 30 or 60 minutes, and "Keep the screen awake while playing" appears in browsers that support it.
• Use noise when a tone is not what you need. "White noise", "Pink noise" and "Brown noise" sit on their own row under the four waveforms. Pink noise falls by about 3 dB per octave and brown noise by about 6 dB per octave, so brown sounds the deepest. When you pick one, the frequency controls disappear. Live playback loops a 10-second noise buffer with a 0.25-second crossfade at the join, so it repeats every 9.75 seconds. A downloaded file is generated fresh for the whole duration, and is named like white-noise.wav.
• Pick the length and format of the download. "Duration" offers 1, 3, 5, 10, 30 and 60 seconds, then 2, 5 and 10 minutes, or "Custom…" for 1 to 600 seconds. Files are 48,000 Hz and 16-bit. A 10-minute WAV is 54.9 MB as mono ("Both") and 109.9 MB as stereo ("Left only", "Right only" or "L then R"). Square, triangle and sawtooth files are built from harmonics that stop below half the sample rate, so they do not alias. MP3 and M4A are made at 192 kbps and need a one-time encoder download of about 30 MB; WAV needs none. A fade of 10 milliseconds at each end avoids clicks.

Common problems and how to fix them

It says "Your browser could not start Web Audio, so the tone cannot play here. Try a recent version of Chrome, Edge, Firefox or Safari."

The page could not create an audio engine. This happens in some in-app browsers (the ones built into other apps) and in very old browsers. Open the page in a current Chrome, Edge, Firefox or Safari and press "Play" again.

"Play" turns into "Stop" but I hear nothing on my phone.

The page prints this advice under the button: "No sound on a phone? Turn off silent mode and raise the media volume." Also check that the Volume slider is above 0%, that "Speakers" is not set to the side your headphones lack, and that the tone is not below what your speaker can reproduce (very low bass tones on a phone speaker, for example). Newer Safari versions are told to play the tone as media so the silent switch is ignored, but older ones still honour it.

It says "Could not create the file. Try WAV or a shorter length."

This message is shown when the WAV could not be built. Pick a shorter "Duration" (a 10-minute stereo WAV is about 110 MB) or try again. If you chose MP3 or M4A, the page shows the encoder's own message instead, for example "Failed to load the encoder. Check your internet connection and try again." The encoder is a one-time download of about 30 MB, so connect to the internet, or choose WAV, which needs no encoder.

It says "Limited to the range 1–22,000 Hz."

You typed a number below 1 Hz or above 22,000 Hz, and the field was set to the nearest allowed value. The tool cannot make a tone outside this range. The value is applied when you leave the field or press Enter, and numbers in range take effect as you type.

The downloaded file is much louder than what I heard, and the Volume slider seems to do nothing to it.

"Louder file: normalise to -1 dBFS (ignores volume)" is ticked by default, so every file is scaled to a peak of -1 dBFS whatever the Volume setting. Untick it and the file takes the Volume setting, with "File peak" showing the level, for example -20.0 dBFS at 20%. If Volume is at 0%, the file is made at the 50% level (about -12.0 dBFS) rather than silent.

How it compares

Live playback uses your browser's built-in oscillator, while downloaded files are rendered by the page itself at 48,000 Hz, so the file itself is identical on any device, while live playback depends on your browser. MP3 and M4A are lossy, so keep WAV when you need an exact test tone. The Volume setting is relative to digital full scale, not to sound pressure, and nothing here is calibrated, so this is not a substitute for a hearing test by a professional or a hardware signal generator. Your speakers decide what you actually hear, and many laptop and phone speakers cannot produce the lowest bass or highest treble in the range. It makes one tone, one sweep or one kind of noise at a time: no chords, no mixing, and no different frequency per ear. For checking left and right speakers, finding a room or speaker resonance with a sweep, or tuning by ear, that is usually enough.