Play any frequency from 1 Hz to 20,000 Hz with this free online tone generator. Set the Hz with the dial, slider or keyboard, pick a sine, square, triangle or sawtooth wave and press Play. It is the quickest Hz sound test for speakers, headphones and your own ears, and it runs in your browser with no download.
Tone Generator
Space play/stop · ↑↓ ±1 Hz · Shift+↑↓ octave
A4±0 cents2.27 msλ 78.0 cm
OUTPUT OFFCONTL + R
Arrow keys: ±1 semitone
Loud setting: turn it down if you use headphones.
Protect your hearing: the volume starts low on purpose. Put headphones on only after pressing Play, raise the level slowly, and keep it low for very high or very low tones: you can barely hear them, but they can still harm your ears. Stop if you feel discomfort or ringing.
Press Play.
The tone is made by your browser (Web Audio), sample-accurate and without a microphone. What you hear also depends on your speakers: phone and laptop speakers rarely play below 100 Hz.
Related Tools
- Frequency Detector
The opposite job: measure the Hz of a sound through your microphone.
- Hearing Test
Find the highest and lowest tones you can hear, step by step.
- Instrument Tuner
Tune any instrument by ear or with the live needle.
- Note to Frequency Converter
Look up the exact Hz of any note in any tuning.
- Spectrogram Viewer
See this tone and its harmonics as a live picture.
- Pitch Matching Game
Hear a tone, sing it back and score your accuracy.
How to Use the Tone Generator
- Press Play. The volume starts at 20% on purpose; raise it slowly.
- Set the frequency: turn the dial (one turn = one octave), drag the logarithmic slider, type a value such as 432 or 1234.5, or use ±1 Hz, ±0.1 Hz, ×2 and ÷2 (one octave up or down).
- Pick a waveform: sine, square, triangle or sawtooth. The trace on the display shows its shape.
- Read the nearest note and cents under the number, for example A4 ±0 cents at 440 Hz, plus the period and the wavelength in air.
- Use a preset (A440, middle C, 432 Hz, 50/60 Hz hum, 1 kHz, 30 Hz bass, 10 kHz, beats, A major chord or a full sweep), or open the Mode card for a sweep or pulse beep.
- Press Copy link to this tone to share it, for example
/tone-generator/?f=440&w=sine.
Keyboard: Space plays and stops, ↑ and ↓ change the tone by 1 Hz, Shift + ↑ / ↓ jumps an octave. On the dial, the arrow keys move one semitone.
Hz Sound Test for Speakers and Headphones
A Hz sound test simply plays known frequencies so you can hear what your system does with them. Start at a low volume and try these:
| Test | Frequency | What it tells you |
|---|---|---|
| Bass extension | 20–60 Hz | Where your speaker or headphones stop producing bass. Phone and laptop speakers usually fade out below 100–150 Hz. |
| Mains hum check | 50 Hz or 60 Hz | Compare with a hum you hear from an amplifier or fridge: Europe, Asia, Africa and Australia use 50 Hz, North America 60 Hz. |
| Reference tone | 1,000 Hz | The standard audio test tone for levels and channel checks. |
| Treble check | 10,000–16,000 Hz | Cheap earbuds and some speakers roll off here; if a tone disappears on one device and not another, it is the device. |
| Full sweep | 20 Hz → 20 kHz | One smooth glide through the whole range; listen for rattles, buzzes and dips. |
For a left/right speaker test, open the Speaker check card and press Left only or Right only: the tone plays in one channel so you can spot swapped or dead channels. The balance slider moves the tone smoothly between the two. When you want to measure a sound instead of making one, use the frequency detector listed above.
A440 Tone and Other Tuning Notes
The A440 tone is the note A above middle C at exactly 440 Hz, the concert pitch most orchestras and tuners use. Press the A440 preset to play it as a pure sine wave, or change the A4 value in the note card to 442 or 415 for other ensembles. Our guide to the A440 tuning standard explains where the number comes from.
Middle C is 261.63 Hz in standard tuning. The 432 Hz preset plays the alternative A that some musicians prefer; the comparison of 432 Hz vs 440 Hz sets out what is fact and what is myth. To pick any other note, choose it in Play a musical note, or see every value on the musical note frequency chart.
The cents figure tells you how far the tone is from the nearest note: 100 cents make one semitone, and about 5 cents is the smallest step most trained ears notice. Read more in cents in music tuning explained.
Sine, Square, Triangle and Sawtooth Waves
| Waveform | Harmonics | How it sounds | Good for |
|---|---|---|---|
| Sine | none, one pure frequency | soft, flute-like | hearing tests, tuning, exact Hz checks |
| Square | odd harmonics (3×, 5×, 7×…), falling as 1/n | hollow, buzzy, like a clarinet or old video game | rattle checks, a clearly audible beep |
| Triangle | odd harmonics, falling fast (1/n²) | between sine and square, soft | gentle reference tones |
| Sawtooth | all harmonics, falling as 1/n | bright, brassy, like a string section | synth sounds, bright test signals |
Square and sawtooth tones are band-limited, so they do not alias into strange extra tones at high frequencies, and every waveform is levelled so switching shape does not make a sudden jump in loudness.
Play Several Tones: Beats and Chords
Switch on Tone 2 and Tone 3 to play up to three frequencies together. Two tones a few Hz apart, such as 440 and 443 Hz, produce beats: the sound swells and fades 3 times per second, exactly the difference between the two. Musicians tune by making the beats slow down and vanish. Three tones in the right ratios make a chord: the A major preset plays A4, C♯5 and E5. It is a handy way to hear intervals before you train them in interval ear training.
Sweep, Pulse and Timer
- Sweep glides from a start to an end frequency over the time you choose. Logarithmic gives each octave equal time (how we hear pitch); linear moves the same number of Hz every second. Play it once, repeat it, or go up and down.
- Pulse turns the tone into beeps with an on time and a pause, from 10 ms to 5 seconds. Each beep fades in and out in 5 ms, so there are no clicks.
- Timer stops the tone by itself after 10 seconds up to 30 minutes.
- Every start and stop fades over a few milliseconds, which keeps speakers and ears free of pops.
Keep Your Hearing Safe
Very high and very low tones can be damaging at levels where they sound quiet, because the ear is less sensitive there. Start low, put headphones on only after the tone is playing, and never turn the volume up just to hear a tone at the edge of your range. Stop if you feel discomfort, pressure or ringing. A shared link never sets the volume, so it always opens at the safe default.
Frequently Asked Questions
What is a Hz sound test?
Playing tones of known frequency (in hertz) to check what a speaker, headphone or ear can reproduce or hear. Type a frequency here, press Play and listen; the sweep preset checks the whole 20 Hz to 20 kHz range in one go.
How accurate is the frequency?
The tone is synthesised by your browser’s audio engine at the exact frequency you set, to 0.01 Hz. In our tests the recorded output matched the setting within 0.01%. Your speakers can change the loudness of a tone, but not its frequency.
Why can’t I hear 30 Hz or 20,000 Hz?
Most phone and laptop speakers cannot play below about 100 Hz, and the upper limit of human hearing falls with age, often to 15–17 kHz for adults. Try headphones, then check your own range with the hearing test above.
What frequency is the A440 tone?
Exactly 440 Hz: the A above middle C in standard tuning. Press the A440 preset or open ?f=440&w=sine.
Can I play two frequencies at the same time?
Yes, up to three. Turn on Tone 2 and Tone 3 in the More tones card; each can have its own frequency and waveform.
Does it work offline or on a phone?
It works in any modern browser on phone, tablet or computer. Once the page has loaded, the tone is generated on your device, so nothing is streamed.