Music and Audio Math: BPM Delay, Note Frequency and Decibels
The calculations behind music production — delay times locked to the beat, note frequencies, how decibels fall with distance, sample rate and bit depth, and sizing audio files.
Note Frequency Calculator
Verified formula Updated Jun 2026 Private — runs on your device
Verified formula
Private
Frequency
440.00
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
How to use the Note Frequency Calculator
The Note Frequency Calculator works out your frequency in an instant. Enter semitones from a4 (440 hz) and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
- Enter the semitones from a4 (440 hz).
- Read off your frequency — the calculator updates automatically, with no button to press.
Formula
The Note Frequency Calculator uses the formula:
Frequency = 440 × (2)^(Semitones from A4 (440 Hz) ÷ 12)
Worked example
For example, with semitones from a4 (440 hz) of 0, the frequency is 440.00.
| Semitones from A4 (440 Hz) | 0 |
|---|
| Frequency | 440.00 |
|---|
Results are estimates for educational use, not professional advice.
Frequently asked questions
Use 440 × 2^(semitones ÷ 12), counting semitones from A4. A4 itself (0 semitones) is 440 Hz.
440 Hz is the modern standard pitch for A above middle C, used to tune most instruments.
Each semitone is one key on a piano. A5 is 12 semitones above A4; one semitone below A4 is G♯4.
An octave is 12 semitones and doubles the frequency. A5 is 880 Hz, twice A4's 440 Hz.
The Note Frequency Calculator uses the formula: Frequency = 440 × (2)^(Semitones from A4 (440 Hz) ÷ 12). For example, with semitones from a4 (440 hz) of 0, the frequency is 440.00.
Enter the semitones from a4 (440 hz). Read off your frequency — the calculator updates automatically, with no button to press.
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