Online Tone Generator — Free Tool
Online tone generator drawn as a laboratory signal generator: drag the dial for any frequency from 20 Hz to 20 kHz, sine, square, sawtooth and triangle waves, note readout, dual-tone mix, pan, stage mode and free WAV export.
Protect your hearing. Start at a low volume. Never raise the volume to make a tone audible. Levels are shown in dBFS, relative to full scale — not SPL.
How it works
Signals are generated live in your browser with the Web Audio API. Nothing is uploaded or recorded. Levels are reported in dBFS, relative to full scale.
A tone generator is the simplest and most useful audio testing tool: one clean, sustained frequency you can point at any speaker, headphone, or audio chain. This one is drawn as a laboratory signal generator — a bench instrument with a real tuning dial, an engraved log-frequency scale, and a chart recorder that draws the tone you are actually hearing.
The instrument: drag the dial, flip the range
The large dial is a precision tuning control, not a slider. Grab it and rotate: the pointer moves over an engraved log scale, and the readout follows in hertz. Because the scale is logarithmic, every octave occupies the same arc, exactly like a bench oscillator. The RANGE switch shifts the dial by decades — ×1 covers 20–200 Hz, ×10 covers 200 Hz–2 kHz, and ×100 covers 2–20 kHz — so the full 20 Hz to 20 kHz band is always within reach while the dial keeps its resolution. FINE slows the drag for vernier adjustments, and NOTE snaps the pointer to the nearest equal-tempered pitch.
The four waveform shutters select sine, square, sawtooth, or triangle. The live scope above the chart shows the output waveform in the time domain, and the recorder strip below plots the primary frequency over the last eight seconds — both are fed by the Web Audio hardware clock, so they draw what is actually playing rather than a decorative loop.
Dual tones, pan, and the output strip
Enable Channel B for a second independent oscillator with its own frequency and waveform; the two mix at the output for intermodulation and beat-frequency demonstrations. The BALANCE fader places the mix in the stereo field, the OUTPUT LEVEL fader sets the oscillator gain in dBFS, and the meter beside it reports true RMS and peak level with a clip indicator. The playable keyboard (A W S E D F T G Y H U J K) turns your computer keys into notes using the selected waveform.
Stage mode, shareable setups and WAV export
- Stage mode — one tap expands the instrument to the full viewport for practice rooms and silent checks, and requests a screen wake lock so the display stays awake. Press Escape to exit.
- Shareable setups — the URL carries the full state (
?freq=432&wave=sine&mode=dual), so a teacher can send an exact tone link. Your last settings are remembered on this device too. - Free WAV export — download the current tone as a 2-second, 16-bit WAV rendered offline in your browser. Stereo pan and the second tone are included, and the file is generated locally.
Work quickly with the keyboard: ↑/↓ or ←/→ nudge by one semitone, hold Shift for ±10 semitones, R cycles the range, and Space starts or stops the tone.
Sine wave generator
A sine wave is a single frequency with no harmonics. It is the reference for hearing tests, speaker sweeps, and level calibration because it contains nothing but the fundamental. Switch to the sine waveform for the purest possible tone.
Audio frequency generator
Use the frequency dial to sweep from 20 Hz to 20 kHz. The readout is always in hertz, and the note name updates live, so “audio frequency generator”, “sine wave generator”, and “tone generator” all describe the same underlying instrument.
Frequency generator for testing
Low frequencies (20–200 Hz) test subwoofers and bass drivers. Mid frequencies (200 Hz–4 kHz) cover most musical content and speech. High frequencies (8–20 kHz) reveal tweeter response and age-related hearing limits. Pair this tool with the subwoofer and hearing tests for a full picture.
Aliases covered on this page: tone generator, frequency generator, audio frequency generator, and sine wave generator.
Frequently asked questions
What is a tone generator?
A tone generator produces a steady sine, square, sawtooth, or triangle wave at a chosen frequency. It is the building block for testing speakers, headphones, and hearing.
Are the frequencies in Hz or note names?
Both. Drag the tuning dial to a frequency and the tool shows the nearest musical note with its cents deviation (for example 440 Hz is A4, 0 ¢).
Can I play two tones at once?
Yes. Enable the second tone to mix two independent frequencies and waveforms, which is useful for intermodulation and beat-frequency demonstrations.
What does the pan control do?
Pan places the tone in the stereo field from left to right, so you can confirm channel and imaging behaviour.
How do I set an exact frequency such as 432 Hz?
Drag the dial to the value shown in the readout, or focus the dial and use the arrow keys. The URL also carries the setting (?freq=432&wave=sine&mode=dual), so a link reopens the exact tone. Flip the RANGE switch between ×1, ×10 and ×100 to move across the 20 Hz–20 kHz band.
Is this safe for my hearing?
Start at a low volume and never raise the volume to make a tone audible. The tool plays only from a user gesture and provides a persistent Stop and Mute. All levels are shown in dBFS, relative to full scale.
What is an online tone generator used for?
An online tone generator plays steady sine, square, sawtooth or triangle waves at exact frequencies for testing speakers, headphones, rooms and hearing. Use it to find rattles, check channel balance, demonstrate beats between close pitches, or learn note-to-frequency mapping. Everything synthesizes live in your browser; nothing is uploaded and levels read in dBFS.