Note Frequency Calculator - Musical Note Hz & Pitch
Calculate the frequency of any musical note, convert between note names and Hz, and explore pitch relationships across the full chromatic scale.
Enter a note name (A–G with optional sharp/flat), octave number, and optional base frequency to compute the exact pitch in Hz.
Note Frequency Calculator - Musical Note Hz & Pitch
Calculate the frequency of any musical note, convert between note names and Hz, and explore pitch relationships across the full chromatic scale.
About the Note Frequency Calculator
Every musical pitch is a sound wave vibrating at a specific number of cycles per second, measured in hertz (Hz). The note A4 — the A above middle C — is universally tuned to 440 Hz in the modern equal temperament standard, though historically it ranged from 415 Hz (Baroque pitch) to as high as 452 Hz in some 19th-century orchestras. The 440 Hz standard was formally adopted by the International Organization for Standardization (ISO) in 1975 and is now used by virtually every instrument manufacturer, tuner, and digital audio workstation.
In equal temperament, the octave is divided into exactly 12 semitones, and each semitone has a frequency ratio of the twelfth root of 2 (approximately 1.05946). This means that going up one semitone multiplies the frequency by this ratio, going down one semitone divides by it, and going up a full octave exactly doubles the frequency. The Note Frequency Calculator uses this formula — f = 440 × 2^((n − 69) / 12) — where n is the MIDI note number, to compute the exact frequency of any pitch.
MIDI note numbers are the standard encoding used in digital music. Middle C (C4) is MIDI note 60. A4 is MIDI note 69. The formula translates naturally: a MIDI note of 69 gives exactly 440 Hz, and each integer step up or down multiplies or divides by the twelfth root of 2.
The wavelength of a sound wave in air depends on the speed of sound, which varies with temperature. At 20°C (68°F), sound travels at approximately 343 meters per second. Wavelength = speed / frequency. For A4 at 440 Hz, the wavelength is 343 / 440 ≈ 0.780 meters (about 78 centimeters). Higher notes have shorter wavelengths; lower notes have longer ones. This matters for loudspeaker design, room acoustics, and microphone placement.
Cents are the logarithmic unit used to measure musical intervals smaller than a semitone. One semitone equals 100 cents; one octave equals 1200 cents. Cents are useful for describing pitch deviations in tuning, vocal pitch correction, and instrument intonation. A violin string tuned 10 cents sharp will sound noticeably out of tune to trained ears even though its frequency differs by less than 0.6%.
The Note Frequency Calculator supports all 12 pitch classes across the full audible range (octaves 0 through 10), handles both sharp (#) and flat (b) notation, and lets you change the base tuning away from the 440 Hz standard — useful for Baroque tuning at A=415 Hz, or for film scoring at A=432 Hz if required by a client.
Note frequency calculator examples
Five representative notes showing frequencies across the piano range and different tuning systems.
| Note | Frequency | Context |
|---|---|---|
| A4, octave 4, base 440 Hz | 440.000 Hz | Concert pitch reference. The standard tuning frequency adopted by ISO 16 in 1975, used by orchestras, recording studios, and digital tuners worldwide. |
| C4 (middle C), octave 4, base 440 Hz | 261.626 Hz | Middle C — the central reference note on a piano keyboard. MIDI note 60. Located near the middle of the 88-key piano range. |
| A4, octave 4, base 432 Hz | 432.000 Hz | 432 Hz tuning used in some alternative music contexts. Each other note is scaled proportionally — C4 becomes ≈256.87 Hz instead of 261.63 Hz. |
| C8 (highest C on piano), octave 8 | 4186.009 Hz | The highest C on a standard 88-key piano. Well within human hearing (20 Hz to 20 kHz) but only young listeners hear it clearly. |
| A0 (lowest note on piano), octave 0 | 27.500 Hz | The lowest A on a standard 88-key piano. At 27.5 Hz, this note is felt as much as it is heard, and requires large speaker cones to reproduce. |
How to use the note frequency calculator
- Type the note name in the Note Name field using letter notation: C, D, E, F, G, A, or B. Add # for sharp (e.g., F#) or b for flat (e.g., Bb).
- Enter the octave number — 4 is the standard middle octave containing middle C and concert A. The full piano range is octaves 0 to 7.
- Optionally change the Base Frequency from the default 440 Hz to another tuning standard such as 432 Hz or 415 Hz.
- Click Calculate to see the exact frequency in Hz, the MIDI note number, the wavelength in air, and the period in milliseconds.
- Use the cents-from-A4 value to check how far any note deviates from A4 in the logarithmic pitch scale.
Note frequency calculator FAQ
What is the standard tuning frequency for A4?
The internationally accepted standard tuning for A4 is 440 Hz, established by ISO 16 in 1975. Some orchestras tune slightly higher (441–444 Hz) for a brighter sound. Historical instruments and Baroque ensembles sometimes use A=415 Hz (one semitone lower), and a minority of musicians prefer A=432 Hz for its claimed psychoacoustic qualities.
How is the frequency of a note calculated?
In equal temperament, the formula is f = 440 × 2^((n − 69) / 12), where n is the MIDI note number. A4 is MIDI 69, C4 is MIDI 60, A5 is MIDI 81, and so on. Each semitone up multiplies the frequency by 2^(1/12) ≈ 1.05946, and each octave up exactly doubles the frequency.
What is equal temperament and why is it used?
Equal temperament divides the octave into 12 equal semitones so that every key sounds equally in tune. Earlier tuning systems like just intonation or meantone temperament sounded better in some keys but noticeably out of tune in others. Equal temperament is the universal compromise that allows a single piano or guitar to play in any key without retuning.
What does the wavelength of a note mean?
Wavelength is the physical distance between successive peaks of the sound wave in air. It equals the speed of sound (≈343 m/s at 20°C) divided by the frequency. A4 at 440 Hz has a wavelength of about 78 cm. Wavelength matters for acoustics — a room's resonant modes and a loudspeaker's bass extension both relate directly to the wavelengths of the notes being reproduced.
What are cents and how are they used for tuning?
A cent is 1/100th of a semitone and is a logarithmic unit for measuring pitch differences. There are 1200 cents in an octave. Tuning apps display deviations in cents to show how flat or sharp a note is. Most trained musicians can detect pitch deviations of about 5–10 cents. Professional tuning targets ±2 cents or better.
Can I use this calculator for non-standard tuning systems?
Yes. By changing the base frequency from 440 Hz to any other value, the calculator rescales all note frequencies proportionally. For A=432 Hz, every note is approximately 32 cents (about 1/3 of a semitone) lower than standard pitch. For Baroque tuning at A=415 Hz, all notes are one semitone lower. Enter your preferred A4 reference frequency to see the resulting frequencies for every note in that tuning system.