Note Frequency Calculator — Musical Pitch to Hz
Select any note (C through B) and octave (0–9) to see its frequency in hertz, its wavelength at room temperature, its period, and the frequencies one octave above and below. You can also adjust the concert-A reference pitch (standard 440 Hz, baroque 415 Hz, modern 442 Hz, etc.).
Note
Octave
Hz
A4 — MIDI note 69
- 1
MIDI note number
(4 + 1) × 12 + 9 = 69 - 2
Semitones from A4
69 − 69 = 0A4 is MIDI note 69, the universal pitch reference at 440 Hz. - 3
Frequency
440 × 2^(0 ÷ 12) = 440
How does this calculator work?
In equal temperament, every note frequency is f = 440 × 2^((MIDI − 69) / 12) Hz, anchored at A4 = 440 Hz. Each octave doubles the frequency; each semitone step multiplies by 2^(1/12) ≈ 1.0595. Select a note and octave to get its Hz, wavelength, period and octave neighbours.
Formula
How this is calculated
Modern Western music uses the equal-temperament system, which divides each octave into 12 equal semitones. Two notes an octave apart have a frequency ratio of exactly 2:1. By dividing that factor evenly, each semitone step multiplies frequency by 2^(1/12) ≈ 1.05946. Concert A4 is anchored at 440 Hz (ISO 16) and assigned MIDI note number 69; every other note is derived by raising or lowering from that anchor.
The formula is f = 440 × 2^((n − 69) / 12), where n is the MIDI note number. For C4 (middle C), n = 60, giving 261.63 Hz; for A5, n = 81, giving 880 Hz — exactly double A4. The reference pitch field lets you explore historical or regional tunings: baroque music often uses A = 415 Hz (one semitone below modern concert pitch), and some orchestras tune to 442 or 443 Hz for a brighter sound.
Wavelength is derived from the speed of sound at sea level and ~20 °C (343 m/s): λ = 343 / f. Lower notes have longer wavelengths and are harder to block acoustically; this is why bass sound travels through walls more easily. The period (1/f in milliseconds) is the duration of one complete oscillation.
Frequently asked questions
Concert A (A4) is internationally standardised at 440 Hz (ISO 16:1975). Some orchestras prefer A = 442 or 443 Hz for a brighter timbre, and baroque ensembles often use A = 415 Hz — a semitone below modern pitch. The reference pitch field lets you switch between any of these.
Middle C is C4 — MIDI note 60. In standard 440 Hz tuning its frequency is 440 × 2^((60 − 69)/12) ≈ 261.63 Hz. It marks the boundary between bass and treble clef notation and is the C on or just below the middle of a standard 88-key piano.
Human pitch perception is roughly logarithmic: each doubling of frequency is heard as the same musical interval (an octave). Equal temperament divides one doubling (2:1) into 12 equal multiplicative steps (each 2^(1/12) ≈ 1.0595), so the same note letter repeats every 12 semitones.
Also known as
TG we-Calculate Editorial Team. (2026). Note Frequency Calculator — Musical Pitch to Hz [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/note-frequency-calculator
TG we-Calculate Editorial Team. "Note Frequency Calculator — Musical Pitch to Hz." TG we-Calculate. 2026. https://we-calculate.com/calculator/note-frequency-calculator.
TG we-Calculate Editorial Team, "Note Frequency Calculator — Musical Pitch to Hz," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/note-frequency-calculator
@misc{wecalculate_note_frequency_calculator, title = {Note Frequency Calculator — Musical Pitch to Hz}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/note-frequency-calculator}}, year = {2026}, note = {TG we-Calculate} }
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