Note Frequency Calculator
Find the frequency in hertz for any musical note and octave, or identify the closest note to a given frequency, free in your browser.
Enter Values
How to use this calculator
- Enter the number of semitones from A4 (440 Hz).
- Read the frequency.
How it works
Frequency = 440 × 2^(semitones ÷ 12) — equal temperament.
Worked example
+3 semitones from A4. = 523.25 Hz (C5).
Common mistakes
- Forgetting +12 semitones = one octave (double the frequency).
- Using a different reference pitch (some use A4 = 442 Hz).
Frequently asked questions
How is a note's frequency calculated?
From equal temperament: each semitone multiplies frequency by 2^(1/12), referenced to A4 = 440 Hz.
Why is A4 = 440 Hz?
It is the modern concert-pitch standard; some orchestras tune slightly higher (442–443 Hz), which shifts every note's frequency.
Why is A4 440 Hz?
It's the modern concert-pitch standard; the whole equal-tempered scale is built around it.
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Cite this tool
Zerdly. (2026). Note Frequency Calculator. Retrieved from https://www.zerdly.com/tools/note-frequency-calculator/
Tip: Enter any known values to calculate the remaining results.
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