Tone Generator

Play a pure sine, square, triangle or sawtooth tone from 20 Hz to 20 kHz and sweep between two frequencies.

Play a test tone

Waveform

Frequency Hz

Sweep between two frequencies

Sweep end Hz

Sweep time 5 s

Level 20%

Frequency: 440 Hz

Nearest note: A4

Cents from that note: 0

Status: Stopped

Warning: turn your volume down before pressing play. A loud tone held close to a speaker or ear can damage hearing and drivers.

Pick a waveform and set the frequency with the slider or an exact value in hertz.
Press Play tone and turn the level up slowly from a low setting.
Tick the sweep box to glide between the frequency and the sweep end instead.

Common questions about the free online tone generator.

Choose a waveform, set the frequency with the slider and press Play tone. The sound is synthesised in your browser with the Web Audio API.

Sine, square, triangle and sawtooth. A sine is a clean single frequency while square and sawtooth waves add harmonics.

The slider covers 20 Hz to 20 kHz on a logarithmic scale, and the box beside it takes any exact value such as 440 for concert pitch A4.

Tick the sweep box and the tone glides from the chosen frequency to the sweep end, then back again, taking the sweep time you set for each pass.

It names the nearest musical note to the current frequency and shows how many cents sharp or flat that frequency sits from the note.

Yes at low levels, but keep the volume down and avoid long loud tones, especially very low or very high frequencies that strain drivers.

Yes. Sweep from 20 Hz to 20 kHz at a low level to check where your hearing or your headphones start and stop responding.

Browsers suspend audio for background tabs in some cases, so the tone stops as soon as the tab is no longer active or the context is closed.

Last updated: October 10, 2026