Musical Note Frequency Calculator: Find Precise Pitch for Any Note and Octave

How to use the tool

1 Choose your desired note

Select a chromatic note (C through B, sharps/flats included).

• Sample A: G♯ (value 8)
• Sample B: F♯ (value 6)

2 Enter its octave

Type an integer from 0 (lowest) to 8 (highest).

• Sample A: 2
• Sample B: 7

3 Set a reference note

Pick any note that you know the frequency of—A is only the default.

• Sample A: F (value 5)
• Sample B: C♯ (value 1)

4 Enter the reference octave

This must match the octave of the reference frequency you type next.

• Sample A: 4
• Sample B: 3

5 Type the reference frequency (Hz)

Acceptable range: 16 – 20 000 Hz.

• Sample A: 349.23 Hz (standard F4)
• Sample B: 277.18 Hz (standard C♯3)

6 Read the result

The calculator multiplies or divides the reference by precise semitone ratios and returns the pitch to two decimals.

Formula used

Semitone distance $$n=(d\!-\!r)+12(o_d\!-\!o_r)$$ Frequency $$f=f_0 \times 2^{rac{n}{12}}$$ where d = desired-note value, r = reference-note value, o_d = desired octave, o_r = reference octave.

Example calculation A

• Desired G♯2, Reference F4 = 349.23 Hz
• n = (8 − 5)+(2 − 4)×12 = −21 semitones
• f = 349.23 × 2^{−21/12} ≈ 103.7 Hz

Example calculation B

• Desired D6, Reference C3 = 130.81 Hz
• n = (2 − 0)+(6 − 3)×12 = 38
• f = 130.81 × 2^{38/12} ≈ 1 175.9 Hz

Quick-Facts

• Concert pitch: A4 = 440 Hz (ISO 16:1975)
• Piano span: 27.5 Hz (A0) – 4 186 Hz (C8) (Steinway & Sons Specs)
• Human hearing: 20 – 20 000 Hz (NIH, 2013)
• An octave equals 12 equal-tempered semitones (Benward & Saker, 2003)

FAQ

What does the calculator do?

It converts any note/octave into an exact frequency using equal-temperament math, eliminating guesswork for tuning (ISO 16:1975).

How accurate is the output?

Outputs use double-precision JavaScript math, giving ±0.01 Hz resolution—far finer than the ±1 Hz tolerance of most clip-on tuners (Peterson Tuners Spec Sheet).

Can I change concert pitch?

Yes. Set A4 to 432 Hz for Verdi tuning or 415 Hz for Baroque repertoire and all other notes shift automatically (Baroque Pitch Standard, ASCAP).

Why does frequency double every octave?

Octave perception follows the logarithmic nature of hearing; doubling f maintains interval identity (Hartmann, Signals Sound and Sensory Perception 2011).

How are sharps and flats handled?

The tool labels enharmonic pairs (e.g., C♯/D♭) with one numeric value, so both map to the same frequency in equal temperament (Benward & Saker, 2003).

What if I enter out-of-range values?

The underlying script blocks numbers below 16 Hz or above 20 000 Hz, matching common audio-interface limits (Focusrite Scarlett Manual).

Is it useful for microtonal music?

Compute adjacent semitones, then derive quarter-tone frequencies using the geometric mean formula shown earlier (Wilson, Microtonal Music, 2018).

Does it work offline?

Yes. The HTML & JS run locally in any browser; no server round-trip is required—“all math executes client-side” (MDN Web Docs).