Use the free Tone and Frequency Generator below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
One number, one sound, total control
Sound is vibration, and the speed of that vibration is measured in hertz: one hertz means one vibration per second, and a tone at 440 hertz vibrates 440 times per second. That single number decides the pitch you hear, and this tone and frequency generator gives you direct control over it. Type any frequency from 20 hertz, the bottom of human hearing, to 20,000 hertz, the top, and the tool plays a pure tone at exactly that frequency. There is no recording, no sample, and no approximation: an oscillator in your browser generates the wave live, at the frequency you asked for.
The slider covers 20 to 2,000 hertz, which is where most practical work happens, while the number box accepts the full range for exact values. That split is deliberate. Dragging is fast when you are exploring, and typing is precise when you need a specific frequency, such as 1,000 hertz for a hearing check or 15,000 hertz to test whether you can still hear high frequencies. Preset buttons for C4, A4, A5, 1,000 hertz, and 15,000 hertz give you one-tap starting points, and the result box always shows the nearest musical note, its distance in cents, and the period of the wave in milliseconds.
Waveforms change the character, not the pitch
The same frequency sounds different depending on the waveform, which is the shape of the vibration. A sine wave is the purest tone, smooth and flute-like, with no extra harmonics. A triangle wave is slightly brighter but still gentle. A square wave is buzzy and hollow, like an old video game, because it adds strong odd harmonics. A sawtooth wave is the brightest and richest of the four, close to the sound of a bowed string, because it contains harmonics at every multiple of the frequency. Switching waveforms while the tone plays, or stopping and restarting with a new one, is the fastest way to learn what harmonics actually sound like, because you hear the same pitch with four different characters in under a minute.
This matters beyond curiosity. Audio engineers test speakers and headphones with sine waves because a pure tone reveals rattles and resonances that music hides. Musicians tune instruments against a reference tone, and the waveform they choose affects how easy the tuning is to hear: a sine wave is cleanest for matching pitch, while a sawtooth is easier to hear in a noisy room. Teachers demonstrate beats, the pulsing sound that appears when two close frequencies play together, by generating two tones a few hertz apart, and this tool supplies one of them.
What the note display tells you
Every frequency sits near a musical note, and the display names it. At 440 hertz the note is A4, exactly, with zero cents of difference. At 445 hertz the note is still A4, but about 20 cents sharp, meaning it sits slightly above the standard pitch. A cent is one hundredth of a semitone, so 100 cents is the distance between two neighbouring piano keys. That number is what tuners live by: an instrument within a few cents of its target sounds in tune, while one 30 or 40 cents off sounds noticeably wrong. If you are testing your hearing, the note display is irrelevant and the frequency number is everything. If you are tuning, the cents number is the one to watch.
The period display is the same information from the other side: the time for one complete vibration. At 440 hertz the period is about 2.27 milliseconds, and at 100 hertz it is 10 milliseconds. Seeing frequency and period together helps students grasp that they are reciprocals: double the frequency, halve the period, and the pitch rises by exactly one octave. That relationship is the backbone of how pitch works, and hearing it while reading the numbers makes it concrete instead of abstract.
Use it safely and well
Keep the volume low, especially above 5,000 hertz, where tones can feel piercing even at moderate levels, and never use high-volume tones with headphones for long periods. Start at a low volume, raise it only until the tone is clear, and take breaks if you are running hearing tests. The tool generates sound only while you ask it to: press Stop when you are done, and nothing continues in the background. Your frequency choices are never uploaded, because the oscillator runs entirely on your device, which also means the tool works wherever your browser works, with no downloads and no sign-up.