Online tone generator
A precise sine wave generator for testing gear, tuning instruments and experiments. Pick a frequency, a waveform and a level, then press play.
Volume first. Turn your device volume down before pressing play, then raise it slowly. Tones start quiet on purpose. High-frequency tones can seem silent and then turn painfully loud when volume goes up. Never raise the volume just because you hear nothing.
How to use the tone generator
- Lower your device volume, then press Play tone. The output starts at −30 dBFS.
- Drag the frequency slider, type an exact value, or use ×2 and ÷2 to jump an octave. The semitone buttons step through the musical scale.
- Use Balance to send the tone to one side only, which is handy for checking a single speaker or earcup.
- Switch waveform to hear how harmonics change the sound. The scope shows the wave shape in real time.
What a frequency number actually means
Hertz counts how many times per second the air pressure swings back and forth. Drag the slider and watch 10 milliseconds of the wave: low notes fit only a few slow cycles, high notes cram in hundreds. Because sound travels at about 343 metres per second in room-temperature air, every frequency also has a physical size, its wavelength.
- Cycles in 10 ms
- 6.3
- One cycle lasts
- 1.58 ms
- Wavelength in air
- 54.3 cm
- Nearest note
- D♯5
A 632 Hz wave is about the length of a ruler. That is why bass fills a whole room and bends round corners while treble beams straight from a tweeter and is easily blocked.
Sound needs air to travel, which is why the Moon is utterly silent; how sunlight falling on it produces the phases we see is the subject of a narrated explainer from ahaboo.
Frequencies with their own page
Some frequencies get searched for by name because they have a job: tuning standards, mains hum, audiometry and hearing-age tones. Each page plays the tone and explains where it is used.
- 20 HzThe bottom edge of human hearing
- 30 HzDeep sub-bass
- 40 HzThe low E of a bass guitar, roughly
- 50 HzEuropean mains hum
- 60 HzNorth American mains hum
- 80 HzThe usual subwoofer crossover
- 100 HzUpper bass
- 128 HzA tuning-fork favourite
- 200 HzLow midrange
- 256 HzScientific middle C
- 432 HzThe alternative tuning
- 440 HzConcert A, the tuning standard
- 500 HzA standard audiometry frequency
- 528 HzThe "Solfeggio" frequency
- 1,000 HzThe reference test tone
- 2,000 HzPresence region
- 4,000 HzPeak ear sensitivity
- 8,000 HzUpper treble
- 10,000 HzHigh treble
- 15,000 HzThe age threshold starts here
- 17,400 HzThe "mosquito" tone
- 20,000 HzThe top edge of human hearing
Questions people ask
What is the difference between sine, square, triangle and sawtooth?
A sine wave is a single pure frequency. Square and triangle waves add odd harmonics (3×, 5×, 7× the base frequency), square much more strongly, so they sound hollow and buzzy. A sawtooth has every harmonic and sounds bright and brassy. Use sine for testing; the others are useful for synth work and for checking distortion.
What frequency range can I play?
From 1 Hz to 22,000 Hz. Your device limits what actually comes out: most phone speakers roll off below about 200 Hz, laptop speakers below about 100 Hz, and many Bluetooth links cut off above 16–20 kHz.
Can I use this to tune an instrument?
Yes. The display shows the nearest note and how many cents sharp or flat the frequency is, based on A4 = 440 Hz equal temperament. Set the generator to the note you need and tune until the beating between the tone and your string disappears.
Is it safe to play tones through headphones?
Yes, at sensible levels. Start with the device volume low; pure tones can sound much louder than music at the same setting, especially between 2 and 5 kHz where the ear is most sensitive.
Keep testing
- Multiple tonesUp to six tones at once: beats, chords, IMD and dial tones.
- Frequency sweepLogarithmic or linear sweeps over any range and duration.
- Spectrum analyzerReal-time FFT of your microphone with peak hold and note readout.