Press Play for a 440 Hz sine tone, then drag or type any frequency from 20 to 20,000 Hz.
Tone Generator: 440 Hz sine tone
Start with your device volume low.
Sine wave · both channels
Hz
Period 2.27 ms
Wavelength 78 cm (30.7 in)
The note A4
Ready. It starts quiet and fades in over half a second.
A steady tone can harm ears and speakers before it sounds loud. Hear nothing? Do not turn it up to find the tone: small speakers cannot play very low tones, and many adults cannot hear very high ones.
Percent of this tool's loudest. Your device volume does the rest.
This online tone generator is an adjustable frequency generator for sound: it plays a constant tone in your browser at any frequency you type, to two decimal places. Left on Sine it is a pure tone generator.
Read the full guide
How to use the sound frequency generator
Press Play: a 440 Hz sine wave fades in at 10 percent volume. Type a frequency on the big number, or open More options to drag the slider or press a chip from 20 Hz to 10,000 Hz. Save WAV downloads about 30 seconds of the same signal.
A tone player for one speaker at a time
Each row under the tool sets a frequency, a waveform and a side in one press. As a tone player or frequency player it can check one speaker: Sine wave from the left speaker sends the sound to the left channel alone.
×2 and ÷2 move the tone one octave. The minus and plus beside the number step it by one hertz.
Need a tone maker for a recording? Save WAV keeps the frequency, waveform and side you picked.
Questions and answers
Is this a frequency generator app?
No. It is a website, so there is nothing to install: this online frequency generator runs in the browser of a phone, tablet or computer. Save WAV gives a file that plays with no connection.
Is it only a sine wave generator?
No. Sine is where it starts. The Waveform buttons switch to square, sawtooth or triangle at the same frequency: a sine is one frequency, and the other three add harmonics, which the presets list.
What range does this sound generator cover?
20 to 20,000 Hz, the range usually given as audible to humans, and no higher. Under 60 Hz and over 14,000 Hz this audio frequency generator warns that you may hear nothing and should not turn it up to find the tone.
Is there a frequency generator with decimals?
Yes. The big number takes two decimal places, so 261.63 Hz plays as typed. For a 1 kHz tone generator type 1000 or 1 kHz on the big number; any other number, such as 2,000, goes there too.
Does it work as a 528 Hz frequency generator?
It plays 528 Hz like any other number: press the big number and type 528. The page is a test tone generator, not a treatment or a hearing test, and it makes no claim for any frequency.
All 12 presets
Four waveforms at 440 Hz 4
Sawtooth wave, every harmonicEvery whole multiple of 440 Hz, even and odd: 880 Hz, 1,320 Hz, 1,760 Hz and so on. Usually described as harsh and clear. A bow drives a string in a sawtooth-like motion, so this wave is a common start for synthesized string sounds.
Sine wave, a pure tone with no harmonicsOne frequency and nothing else, which is why a sine wave is called a pure tone. It is the sound this page opens with: 440 Hz, the A above middle C that instruments are tuned to.
Square wave, strong odd harmonicsThe same odd harmonics as the triangle, far stronger: each has the fundamental's amplitude divided by its number, so the third is at a third and the fifth at a fifth. Musicians often describe the sound as hollow.
Triangle wave, faint odd harmonicsThe 440 Hz fundamental plus odd harmonics only: 1,320 Hz, 2,200 Hz, 3,080 Hz and up. Each is weaker by the square of its number, so the third harmonic has a ninth of the fundamental's amplitude. Of the three, the nearest to a sine.
Show all 12 presets (8 more)
Waveforms low and high 4
High square wave, two octaves upA 1,760 Hz square wave: odd harmonics at 5,280 Hz, 8,800 Hz and 12,320 Hz. A saved file keeps nothing above 20,000 Hz, so its last harmonic is the eleventh, at 19,360 Hz.
High triangle wave, two octaves up1,760 Hz, two octaves over the 440 Hz rows. The first two harmonics are at 5,280 Hz and 8,800 Hz, with a ninth and a twenty-fifth of the fundamental's amplitude.
Low sawtooth wave, two octaves downA 110 Hz sawtooth has a harmonic every 110 Hz: 220 Hz, 330 Hz, 440 Hz and on. A saved file keeps them up to the 181st, at 19,910 Hz, the last one under the 20,000 Hz ceiling.
Low square wave, two octaves down110 Hz, two octaves under the 440 Hz rows. Its harmonics sit at 330 Hz, 550 Hz and 770 Hz, so a speaker too small to play much at 110 Hz still plays those. Press Sine afterward to hear the 110 Hz fundamental by itself.
One side at a time 4
Sine wave from the left speakerThe 440 Hz sine in the left channel and silence in the right. On headphones the tone should sit wholly in the left ear.
Sine wave from the right speakerThe mirror of the row above. The page sends nothing to the other channel, so a faint tone on the silent side comes from the equipment and not from this page.
Square wave from the left speakerA 440 Hz square wave has odd harmonics from 1,320 Hz to well past 10,000 Hz, and a tweeter typically covers 2,000 to 20,000 Hz. So where the left speaker has a woofer and a tweeter, both get something to play.
Square wave from the right speakerThe right-hand twin of the row above. Save WAV writes a sound that sits on one side as a two-channel file, and a sound on both sides as one channel.
How this list was compiled: Presets written for this page. Each one is a frequency, a waveform and a side, which are settings of this page's own tone generator, and every tone is made in the visitor's browser. Which harmonics each waveform carries was checked on 2026-10-02 against Wikipedia: https://en.wikipedia.org/wiki/Sine_wave (a sine wave is one frequency and no harmonics, a pure tone), https://en.wikipedia.org/wiki/Square_wave_(waveform) (only odd harmonics; often described as sounding hollow), https://en.wikipedia.org/wiki/Triangle_wave (only odd harmonics, which fall away with the square of the harmonic number, where a square wave's fall away with the number itself) and https://en.wikipedia.org/wiki/Sawtooth_wave (even and odd harmonics; a harsh, clear sound; a bow drives a string in a sawtooth-like motion, which is why the wave is used for synthesized string sounds). That 440 Hz is the tuning standard for the A above middle C was checked at https://en.wikipedia.org/wiki/A440_(pitch_standard), and that a tweeter typically covers 2,000 to 20,000 Hz at https://en.wikipedia.org/wiki/Tweeter. Wikipedia's text is under CC BY-SA 4.0; the facts were checked there and the wording is this site's own. Computed, not looked up: every harmonic frequency (the fundamental multiplied by a whole number) and the amplitude fractions (one over the harmonic number for a square wave, one over its square for a triangle wave). How a saved file is made (no harmonic above 20,000 Hz; one channel unless the sound is on one side, then two) was read from this site's own tone generator code on 2026-10-02. Licence: own work