Online Tone Generator — Free Frequency | LazyTools
Music Tool

Online Tone Generator — Pure Tones, Binaural Beats & Note Picker

Generate pure tones at any frequency using sine, square, sawtooth or triangle waveforms. The Note Picker tab shows a piano keyboard — click any key to instantly set its frequency and play the tone. Furthermore, the Binaural Beat mode plays two slightly different frequencies in each ear — useful for focus, relaxation and sleep. One-click presets include 40 Hz Gamma, 10 Hz Alpha, 4 Hz Theta and 1 Hz Delta. Download any tone as a 10-second WAV file.

4 waveformsNote Picker keyboardBinaural Beats + presetsWAV downloadFrequency → note display
A4
Closest note
4
Octave
0
Cents offset
77.5
Wavelength (cm)

How to use the Online Tone Generator

1

Enter a frequency or use the Note Picker

Type any frequency in Hz in the Single Tone tab (20–20,000 Hz). Furthermore, the Note Picker tab shows a three-octave piano keyboard — click any key to set its exact frequency automatically and begin playing. The stat strip shows the closest musical note, octave, cents offset and wavelength.

2

Select a waveform

Choose from sine (pure, smooth), square (buzzy, rich in harmonics), sawtooth (bright, harsh) or triangle (warm, gentle). Furthermore, each waveform has a distinct timbre — sine is the purest tone with no harmonics; square adds strong odd harmonics; sawtooth adds all harmonics; triangle has softer, quieter harmonics.

3

Adjust volume and press Play

Set the volume slider to a comfortable level — start low, especially with headphones. Furthermore, click Play Tone or press Enter to start the tone. The tone plays continuously until you press Stop. The frequency stat strip updates instantly when you change the frequency while playing.

4

Try the Binaural Beats mode

Click the Binaural Beats tab and select a preset — 40 Hz Gamma for focus, 10 Hz Alpha for relaxation, 4 Hz Theta for meditation or 1 Hz Delta for sleep. Furthermore, put on headphones (essential for binaural beats) and press Play Binaural Tone. The left and right ear hear slightly different frequencies, creating a perceived beat at the difference.

5

Download a WAV file

Click Download WAV to render a 10-second WAV file of the current tone at the current frequency and waveform. Furthermore, this file is compatible with every audio software and can be used as a reference tone, test signal or sound design starting point. The filename includes the frequency for easy identification.

The four waveforms and their uses

Each waveform has a distinct harmonic content that determines its timbre. Furthermore, the same frequency played through different waveforms sounds completely different — this is the foundation of synthesis and sound design.

WaveformHarmonic contentSound characterCommon uses
SineFundamental only (no harmonics)Pure, smooth, clinicalTuning reference, hearing tests, tinnitus matching, audio testing
SquareOdd harmonics (3rd, 5th, 7th…)Buzzy, hollow, retroChiptune/8-bit sounds, clarinets, vintage synths
SawtoothAll harmonics (odd and even)Bright, harsh, aggressiveStrings, brass simulation, lead synth sounds
TriangleOdd harmonics (quieter than square)Soft, warm, flute-likeFlutes, soft leads, sub bass augmentation

Musical note frequencies

The standard tuning reference is A4 = 440 Hz — the note A in the fourth octave. Furthermore, all other notes derive from this reference using the equal temperament formula: each semitone is a ratio of 2 to the power of 1/12 (approximately 1.05946). Moreover, the Note Picker tab handles this calculation automatically — click a key and the correct frequency appears instantly.

How tone frequency relates to musical notes

The equal temperament system places all 12 semitones of the octave at equal frequency ratios. Furthermore, doubling a frequency raises the pitch by exactly one octave. This means A4 = 440 Hz, A5 = 880 Hz and A3 = 220 Hz.

Frequency = 440 × 2^((MIDI note − 69) / 12)
A4 = MIDI 69 = 440 Hz (standard concert pitch)
Middle C = MIDI 60 = 261.63 Hz
C5 = MIDI 72 = 523.25 Hz
Wavelength = 343 m/s ÷ frequency (speed of sound in air at 20°C)

How binaural beats work

Binaural beats require headphones. Furthermore, the left ear hears one frequency and the right ear hears a slightly different frequency. The brain perceives the difference between the two frequencies as a slow pulsing beat. Moreover, at 10 Hz difference (Alpha range), some users report increased relaxation. At 40 Hz (Gamma range), users report heightened focus. These effects are studied but not conclusively proven in clinical research.

Worked example: setting up a binaural Alpha session

A user wants to use 10 Hz Alpha binaural beats for a 20-minute relaxation session. Here is the setup:

SettingValueNote
Left ear frequency200 HzA carrier in the comfortable hearing range
Right ear frequency210 HzCarrier + 10 Hz beat frequency
Perceived beat10 Hz (Alpha)The difference the brain perceives
WaveformSine (both ears)Purest tone for binaural use
Volume20–30%Just audible — keep it low
The 10 Hz Alpha preset configures these values automatically. Furthermore, headphones are essential — without them, both frequencies mix in air and no binaural beat occurs. The Alpha range (8–13 Hz) is associated with relaxed but alert mental states. Use at a low, comfortable volume and avoid driving or operating machinery during binaural sessions.

What is a tone generator?

A tone generator produces sound at a precisely controlled frequency and waveform. Furthermore, it uses electronic oscillation — in this case the Web Audio API — to create tones from 20 Hz (the lower limit of human hearing) to 20,000 Hz (the upper limit for most adults). A pure sine wave contains only the fundamental frequency with no harmonics.

Tone generators have been core instruments in audio engineering for over a century. Furthermore, they test microphones, speakers, amplifiers and hearing. Sound designers use them as synthesis starting points. Music teachers use reference tones to help students tune instruments. Moreover, the tool also serves occupational health — audiologists use calibrated tones to test hearing thresholds across frequencies.

Tinnitus matching

People with tinnitus often use tone generators to identify the frequency of their ringing. Furthermore, by matching the generator frequency to the perceived ringing, they can identify the precise pitch. This information helps audiologists design tinnitus masking therapies. Moreover, knowing the tinnitus frequency also helps users find sound masking content tuned to that specific range.

Audio equipment testing

Audio engineers use tone generators to test equipment frequency response. Furthermore, sweeping from 20 Hz to 20,000 Hz through speakers reveals resonances, roll-offs and distortion points. Moreover, the downloadable WAV files can be played through any audio system to test frequency response without requiring specialised equipment.

Why tone generators matter for musicians and engineers

Every piece of audio equipment handles different frequencies differently. Furthermore, a subwoofer designed to reproduce 20–80 Hz will sound very different from a tweeter designed for 2,000–20,000 Hz. A tone generator lets you probe these differences directly. Moreover, testing monitors, headphones and room acoustics with sine sweeps reveals the true frequency response of your listening environment.

The Note Picker keyboard bridges music theory and signal analysis. Furthermore, when you need to know the exact frequency of middle C for a software synthesiser calibration, clicking the C4 key gives you 261.63 Hz instantly. Moreover, the cents display shows how far any custom frequency deviates from the nearest equal temperament note — valuable for just intonation experiments and microtonal music.

Binaural beats in productivity and wellness

Binaural beats have gained significant attention in wellness and productivity communities. Furthermore, while the clinical evidence remains mixed, millions of users report benefits for focus, relaxation and sleep onset when using binaural frequencies consistently. Moreover, the four presets — Gamma (40 Hz), Alpha (10 Hz), Theta (4 Hz) and Delta (1 Hz) — cover the four main brainwave ranges studied in this field.

Frequently asked questions

Extended exposure to loud sounds at any frequency can damage hearing. Furthermore, keep the volume at a comfortable, quiet level — the slider should stay below 30% in most cases, especially with headphones. Very high frequencies (above 15,000 Hz) become inaudible to many adults and serve mainly for equipment testing. Moreover, very low frequencies (below 30 Hz) require significant volume to hear and can cause ear fatigue.
The scientific evidence for binaural beats is intriguing but not conclusive. Furthermore, a number of small studies report measurable effects on relaxation, focus and sleep onset, but larger controlled trials show more mixed results. Moreover, the effect requires headphones — without stereo separation, no binaural beat is perceived. Many users report subjective benefits regardless of the research status. Keep volume low and use for short sessions to start.
A440 is the international standard concert pitch — the note A in the fourth octave is defined as exactly 440 Hz. Furthermore, this standard was adopted internationally in 1939 and confirmed by ISO in 1975. Some orchestras and ensembles tune to 442–443 Hz for a brighter sound. Moreover, historical instruments often used A415 (a semitone below 440 Hz) — the baroque standard. You can explore these alternatives using the frequency input.
The waveform determines which harmonics are present alongside the fundamental frequency. Furthermore, a sine wave contains only the fundamental — it is the purest possible tone. A sawtooth wave adds all harmonics (2nd, 3rd, 4th… in decreasing amplitude), creating a bright, rich sound. Moreover, the brain interprets this as a completely different timbre even at the same fundamental frequency — this is the entire basis of electronic synthesis and why two instruments can play the same note but sound completely different.
Yes — the binaural beat presets are specifically designed for these uses. Furthermore, the 1 Hz Delta preset (associated with deep sleep states), 4 Hz Theta (deep meditation) and 10 Hz Alpha (relaxed alertness) are the most commonly used ranges for these purposes. Use headphones, set the volume to a barely audible level and allow 10–20 minutes for any effect to develop. Moreover, the tone generator works silently in your browser tab while you do other things.

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