Frequency Precision & Calibration Tones

Dial in exact frequencies to 0.01 Hz for reference and calibration

Set any frequency to two decimals — try 440.25 Hz.

What 0.01 Hz precision means

You can set any frequency between 20 Hz and 20,000 Hz to two decimal places — a resolution of 0.01 Hz. The exact value you enter is sent straight to the browser's oscillator, so a value like 440.25 Hz plays at 440.25 Hz rather than being rounded to a whole number. This matters for calibration and reference work, where a fraction of a hertz can be exactly the difference you are checking for.

How to set an exact frequency

There are three ways to reach a precise value:

Type the value directly into the Hz box, including decimals — for example 440.25.
Nudge it with the step buttons: ±0.1 Hz for fine adjustments, ±1 Hz and ±10 Hz for larger jumps.
Click the Hz box and use the up and down arrow keys to step by 0.01 Hz at a time.

Common reference & calibration tones

These frequencies are widely used as references. Select one to hear it, then fine-tune from there.

Frequency	Common use
440 Hz	Concert pitch (A4) — the standard tuning reference defined by ISO 16.
256 Hz	Scientific (philosophical) pitch, where middle C is an exact power of two.
1000 Hz	A standard reference tone for audio level and equipment checks.
50 / 60 Hz	Mains-frequency tones (50 Hz or 60 Hz) for tracing electrical hum and ground loops.

Tip: The tool sets the frequency to the exact value you enter, but the pitch your speakers or headphones actually produce also depends on your device's audio hardware and its sample rate.

Sources: W3C Web Audio API

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