A versatile online tone generator
This free online tone generator allows you to produce continuous audio frequencies ranging from 20 Hz up to 20,000 Hz. Whether you need to tune a musical instrument, test the frequency response of your audio equipment, or conduct a simple science experiment, this tool provides precise, real-time control over your audio output.
Because the tool relies entirely on your browser's native Web Audio API, everything runs locally on your device. There is no audio streaming from a server, meaning the generator responds instantly to your inputs and works perfectly without consuming your internet bandwidth.
How to use the frequency generator
The interface is designed for both precision and exploration. You can control the output in several ways:
Logarithmic Slider: The main frequency slider is logarithmic rather than linear. Because human hearing perceives pitch logarithmically, this design gives you much finer control over lower frequencies (where small changes are highly noticeable) while still allowing you to sweep all the way up to 20,000 Hz.
Exact Input & Fine Tuning: If you need a specific pitch, you can type it directly into the frequency box. Below the slider, you will find fine-tuning buttons. The -1 and +1 buttons allow for precise adjustments, while the ÷2 and ×2 buttons instantly drop or raise the pitch by exactly one octave.
Quick Presets: We have included common frequency presets at the bottom of the tool. These include 50 Hz and 100 Hz (useful for testing subwoofer hum), 261.63 Hz (Middle C), the standard 440 Hz tone (A4), and high-frequency benchmarks like 10,000 Hz and 15,000 Hz.
Live Adjustments: You do not need to stop and restart the audio to make changes. You can adjust the frequency, volume, and stereo balance (pan) while the tone is playing. The tool applies a slight mathematical smoothing to these changes to prevent harsh audio artifacts or clicking.
Understanding the waveforms
This tool functions as more than just a basic sine wave generator. You can choose between four distinct waveforms, each with a different harmonic structure and practical application:
- Sine: The purest sound possible. A sine wave consists of a single fundamental frequency with absolutely no overtones or harmonics. It is the standard choice for an Hz sound test, checking speaker distortion, or testing hearing limits.
- Square: A harsh, hollow-sounding wave that contains only odd harmonics. Square waves are highly recognizable as the foundation of classic 8-bit video game music and synthesizers.
- Sawtooth: A bright, buzzing sound that contains both even and odd harmonics. Because it is so rich in harmonics, it is frequently used in subtractive synthesizers to create complex sounds like strings or brass.
- Triangle: Similar to a square wave in that it only contains odd harmonics, but the volume of these harmonics drops off much faster. The result is a sound that is softer and less abrasive than a square wave, but slightly brighter than a pure sine wave.
Common uses for a tone generator
Tuning Instruments: The most common use for a frequency generator is tuning musical instruments by ear. By playing a continuous 440 Hz tone, musicians can tune their strings or brass instruments to standard concert pitch. If you need visual feedback while tuning, you can also use our dedicated Guitar Tuner.
Speaker and Headphone Testing: Audio enthusiasts frequently use frequency sweeps to test the capabilities of new speakers or headphones. By sweeping from 20 Hz to 20 kHz, you can identify dead spots, rattling components, or crossover distortion in your setup. You can also use the balance slider to isolate the left or right channels. For a more guided hardware check, try our Speaker Test tool.
Hearing Tests: While not a substitute for a medical audiogram, a tone generator is a quick way to test the upper limits of your hearing. Age and noise exposure naturally reduce our ability to hear high frequencies. By slowly raising the pitch, you can find the exact point where the sound fades out for you.
Science and Education: Tone generators are excellent educational tools for demonstrating the physics of sound. Teachers can use them to explain the relationship between pitch and frequency, demonstrate how octaves work (using the ×2 button), or show how different waveforms alter the timbre of a sound. If you are teaching musical timing alongside pitch, our Metronome is a helpful companion tool.
Safety and hardware limitations
When using any audio testing tool, always start with your system volume set very low. Pure tones, especially high-frequency sine waves, carry a significant amount of acoustic energy. Playing them at maximum volume can be physically painful and may permanently damage your hearing or burn out the tweeters in your speakers.
Additionally, keep in mind the physical limitations of your hardware. If you set the generator to 30 Hz and hear nothing, it does not necessarily mean the tool is broken or your hearing is failing. Most built-in laptop, monitor, and smartphone speakers are physically incapable of moving enough air to reproduce deep sub-bass frequencies. To accurately test frequencies below 80 Hz, you will need a dedicated subwoofer or a pair of high-quality, over-ear headphones.