How to use the tone generator
- Enter a frequency from 20 to 20,000 Hz, or pick a common tone.
- Choose a wave shape: sine, triangle, square or sawtooth, and the volume, starting low.
- Optionally choose a timer so the sound stops by itself.
- Press Play tone. You can change the frequency, shape and volume while it plays. Press Stop when you are done.
What the tone is
A tone is a wave that repeats at a steady rate, and the number of repeats a second is its frequency in hertz. A higher frequency sounds higher in pitch. 440 Hz is the A above middle C, the usual tuning reference, and 261.63 Hz is middle C. The page shows the nearest note and how far off it is in cents, where 100 cents is one semitone: 1,000 Hz is closest to B5 and 21 cents sharp, and 100 Hz is closest to G2 and 35 cents sharp.
It also shows the period, which is the time for one repeat, and the wavelength in air at 343 meters a second. At 440 Hz the period is 2.273 milliseconds and the wavelength is about 78 centimeters. The wave shape changes the color of the sound. A sine is pure, a triangle is soft with a few overtones, and square and sawtooth waves are bright and buzzy because they hold many overtones.
Using it safely
Sound starts only when you press Play, and the volume begins low. Loud sound, and very high or very low tones, can hurt hearing and damage small speakers, so raise the volume slowly and never use headphones at an uncomfortable level. Square and sawtooth waves are scaled down because they sound louder than a sine at the same setting. Many small speakers cannot play low frequencies, so a tone below about 100 Hz may be quiet or silent on a phone.
This is a simple signal source for tuning, checking speakers and headphones, finding a rattle or testing a sound system. It is not a hearing test and should not be used to judge your hearing. If the browser cannot start audio, for example when no output device is available, the page says so and you can press Play again.
Related tools and privacy
To tune an instrument with the microphone, use the Online Tuner. To convert between note names and frequencies, use the Note Frequency Converter, and to play notes on a keyboard the Online Piano. The White Noise Generator plays steady noise, and the Song Length Calculator plans the length of a piece. The sound is generated in your browser, and nothing is recorded or uploaded.
Assumptions and limits
- The frequency is from 20 to 20,000 Hz. Your device may not reproduce the whole range.
- Notes use equal temperament with A4 at 440 Hz. The wavelength uses 343 meters a second.
- Volume is scaled by wave shape, so equal slider settings are not equal loudness across shapes.
- Nothing is recorded, uploaded or stored.
Frequently asked questions
How do I play a specific frequency?
Enter the frequency in hertz, choose a wave shape and press Play tone. The page plays it until you stop it or a timer ends it, and shows the nearest note.
What frequency is the note A?
The A above middle C is 440 Hz in the usual tuning. Other octaves of A are 220 Hz, 880 Hz and so on, doubling or halving each time.
Why can I not hear low tones on my phone?
Small speakers cannot move enough air to make low frequencies, so tones below roughly 100 Hz may be very quiet or silent even though they are playing. Headphones or a larger speaker help.
Is it safe to play a tone loudly?
No. Loud sound can damage hearing and speakers. Start with a low volume, raise it slowly, and stop if it is uncomfortable. The tool is not a hearing test.