Use the free Tone Generator Online below: pick a frequency, pick a wave shape, press Play, and listen to a steady tone in your browser. Sound starts only after you press Play.
How to use the tone generator
Set the frequency slider to the pitch you want, from 20 Hz to 2000 Hz. Choose a wave shape: sine for a smooth pure tone, square for a buzzy tone, triangle for a soft tone, or sawtooth for a bright tone. Set the volume, then press Play tone. The tone plays until you press Stop tone. You can move the frequency slider while the tone plays, and the pitch changes at once. You can also change the wave shape while it plays, so you can compare sounds without stopping.
The live waveform picture shows the shape of the sound you picked. A sine wave is a smooth curve. A square wave jumps between high and low. A triangle wave rises and falls in straight lines. A sawtooth wave climbs slowly and drops fast. Below the picture, the tool names the note closest to your frequency. This helps when you tune an instrument or test what a pitch sounds like.
Worked example: 440 Hz sine is concert A
Set the frequency to 440 Hz and the wave shape to sine, then press Play. You hear a smooth tone, and the tool shows that 440 Hz is closest to note A4. This is concert A, the pitch orchestras tune to before a concert. It is a middle pitch, easy to hear on most speakers and headphones. Now move the slider to 880 Hz without stopping. The note is still A, but one octave higher, and it sounds clearly higher and brighter. Move it down to 220 Hz and you hear the same note one octave lower, deeper and calmer. This one test shows how doubling the frequency raises a note by one octave, and halving it lowers it by one octave.
Try a second test with wave shapes. Keep 440 Hz, switch to square, and the tone turns buzzy and harsh. Switch to triangle and it turns soft and mellow. Switch to sawtooth and it turns bright and full. The pitch stays the same in all four cases, because the frequency did not change. Only the colour of the sound changes. This is why musicians talk about pitch and tone colour as two separate things.
What you can use it for
Musicians use a steady tone to tune an instrument by ear. Play 440 Hz, then play the A string or key on your instrument, and adjust until the two sounds match and the beating between them stops. Teachers use tones to show students what frequency means and how octaves work. People who test speakers or headphones use low tones to check bass and high tones to check treble. A steady tone is also useful for hearing tests at home, for checking whether a room echoes, and for simple sound experiments with children.
You can also use the tone as a reference for singing. Play a note, sing it back, and check whether your voice matches. Start with middle pitches near 440 Hz, because very low and very high tones are harder to sing in tune. If you practise an instrument, play a slow scale against a steady tone and listen for notes that clash. This trains your ear faster than playing alone.
Honest limits
Sound starts only after you press Play, because browsers block sound before you click anything. If the Tone.js sound library fails to load, the tool shows a plain error instead of a fake tone, so reload the page and try again. Pitch accuracy depends on your device and browser, but for tuning and practice it is close enough. Very low tones under 100 Hz may be hard to hear on small phone speakers, so use headphones for bass tests. This tool plays one steady tone at a time, so it cannot play chords or melodies.
Frequently asked questions
What frequency should I start with? Start with 440 Hz sine. It is concert A, a comfortable middle pitch, and most people hear it clearly. From there, move up or down to explore.
Why does the square wave sound harsher than the sine wave? A sine wave has only one pure pitch. A square wave adds many higher overtones on top of the same pitch, and those extra overtones make it sound buzzy and harsh.
Can I use this tone to tune a guitar? Yes. Play 440 Hz for the A string, then tune the string until it matches. For other strings, set the frequency to the pitch of that string and repeat the same step.
Why is there no sound until I press Play? Browsers block sound until the user clicks, to stop sites from playing ads out loud. Pressing Play is the click that unlocks sound, and this is normal on every browser.
Spanish version: Generador de Tonos Online