liminfoNote Frequency Calculator
Free web tool: Note Frequency Calculator
A4
440.00 Hz
MIDI Note: 69
All Notes in Octave 4
Full Frequency Table (Hz)
| Note | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|---|---|
| C | 16.35 | 32.70 | 65.41 | 130.81 | 261.63 | 523.25 | 1046.5 | 2093.0 | 4186.0 |
| C# | 17.32 | 34.65 | 69.30 | 138.59 | 277.18 | 554.37 | 1108.7 | 2217.5 | 4434.9 |
| D | 18.35 | 36.71 | 73.42 | 146.83 | 293.66 | 587.33 | 1174.7 | 2349.3 | 4698.6 |
| D# | 19.45 | 38.89 | 77.78 | 155.56 | 311.13 | 622.25 | 1244.5 | 2489.0 | 4978.0 |
| E | 20.60 | 41.20 | 82.41 | 164.81 | 329.63 | 659.26 | 1318.5 | 2637.0 | 5274.0 |
| F | 21.83 | 43.65 | 87.31 | 174.61 | 349.23 | 698.46 | 1396.9 | 2793.8 | 5587.7 |
| F# | 23.12 | 46.25 | 92.50 | 185.00 | 369.99 | 739.99 | 1480.0 | 2960.0 | 5919.9 |
| G | 24.50 | 49.00 | 98.00 | 196.00 | 392.00 | 783.99 | 1568.0 | 3136.0 | 6271.9 |
| G# | 25.96 | 51.91 | 103.83 | 207.65 | 415.30 | 830.61 | 1661.2 | 3322.4 | 6644.9 |
| A | 27.50 | 55.00 | 110.00 | 220.00 | 440.00 | 880.00 | 1760.0 | 3520.0 | 7040.0 |
| A# | 29.14 | 58.27 | 116.54 | 233.08 | 466.16 | 932.33 | 1864.7 | 3729.3 | 7458.6 |
| B | 30.87 | 61.74 | 123.47 | 246.94 | 493.88 | 987.77 | 1975.5 | 3951.1 | 7902.1 |
About Note Frequency Calculator
The Note Frequency Calculator converts any musical note to its exact frequency in hertz using the standard equal temperament formula: f = A4 × 2^((n − 49) / 12), where n is the MIDI note number and A4 is the reference pitch. The calculator covers all 12 chromatic notes (C, C#, D, D#, E, F, F#, G, G#, A, A#, B) across 9 octaves (0 through 8), giving access to 108 distinct pitch values — the complete range of a standard 88-key piano and then some.
One of the key features is support for four common tuning standards: A4 = 432 Hz (favored by some performers for its perceived warmth), A4 = 440 Hz (the ISO 16 international standard used by most orchestras and recording studios), A4 = 442 Hz (common in European orchestras and some chamber ensembles), and A4 = 444 Hz (used in certain early music and period instrument contexts). Switching between these tunings instantly recalculates every frequency in the table.
The tool provides three views: a single-note frequency display showing the selected note, octave, and frequency prominently; an octave panel showing all 12 notes in the currently selected octave for quick comparison; and a full chromatic frequency table showing all 108 frequencies (12 notes × 9 octaves) in a scrollable grid. Each note is also labeled with its MIDI note number, which is essential for synthesizer programming, DAW configuration, and digital audio work.
Key Features
- Converts any of 12 chromatic notes (C through B) across octaves 0–8 to exact Hz
- Supports four tuning standards: A4 = 432, 440, 442, and 444 Hz
- Displays MIDI note number for each selected pitch (e.g., A4 = MIDI 69)
- Octave panel shows all 12 notes of the current octave for side-by-side comparison
- Full chromatic frequency table: 108 frequencies in a scrollable 12×9 grid
- Highlights the selected note in both the octave panel and the full table
- Real-time recalculation when tuning standard, note, or octave changes
- 100% client-side — no server calls, works offline, completely free
Frequently Asked Questions
What frequency is middle C (C4)?
At the standard A4 = 440 Hz tuning, middle C (C4) is 261.63 Hz. At A4 = 432 Hz it is 256.87 Hz. At A4 = 442 Hz it is 262.81 Hz. The exact value depends on the tuning reference because in equal temperament all notes are derived by multiplying or dividing the reference pitch by powers of the twelfth root of 2 (2^(1/12) ≈ 1.05946).
What is the formula used to calculate note frequencies?
The equal temperament formula is: f = A4 × 2^(semitones_from_A4 / 12). Semitones from A4 = (octave − 4) × 12 + (note_index − 9), where note index is the chromatic position (C=0, C#=1, D=2, D#=3, E=4, F=5, F#=6, G=7, G#=8, A=9, A#=10, B=11). This formula places exactly 12 equal semitones per octave, doubling the frequency with each octave increase.
Why do some people use 432 Hz instead of 440 Hz?
432 Hz is a tuning standard advocated by some musicians and music theorists who claim it sounds warmer and more natural than 440 Hz. The claim is largely subjective and scientifically unsubstantiated, but it remains popular in certain communities, particularly for meditative music, sound healing, and some folk and world music recordings. The standard A4 = 440 Hz was adopted as the ISO 16 international standard in 1955 and is used by virtually all professional orchestras and recording studios.
What is a MIDI note number?
MIDI (Musical Instrument Digital Interface) note numbers are integers from 0 to 127 used to identify pitches in digital music systems. Middle C (C4) is MIDI note 60, and A4 (concert pitch) is MIDI note 69. Each increment of 1 MIDI note corresponds to one semitone. MIDI numbers are used by synthesizers, DAWs (Digital Audio Workstations), virtual instruments, and music notation software to specify pitches precisely.
What is the highest and lowest audible note?
The standard range of human hearing is roughly 20 Hz to 20,000 Hz. The lowest note in the calculator (C0) is about 16.35 Hz at A4 = 440 Hz, which is below the threshold of most adults' hearing. The highest note (B8) is about 7,902 Hz. A standard piano spans A0 (27.5 Hz) to C8 (4,186 Hz). Most musical content lies between C2 (~65 Hz) and C7 (~2,093 Hz).
How do octaves relate to frequency?
Each octave doubles the frequency. Going from A4 (440 Hz) up one octave to A5 gives exactly 880 Hz. Going down one octave to A3 gives 220 Hz. This doubling relationship is the basis of the equal temperament system and explains why notes with the same letter name (C4, C5, C6) sound similar — they share the same harmonic overtones.
What tuning do orchestras use?
Most modern Western orchestras tune to A4 = 440 Hz as specified by ISO 16. However, some orchestras — particularly in Europe — use A4 = 442 Hz or even 443 Hz, believing the slightly higher pitch produces a brighter, more projected sound. Some baroque and early music ensembles use lower tunings such as A4 = 415 Hz (approximately one semitone below modern pitch) to match historical instrument designs.
Can I use this to tune a guitar or other instrument?
You can use the frequency values as a reference for electronic tuners or tuning apps. The standard guitar strings from low to high are E2 (82.41 Hz), A2 (110.00 Hz), D3 (146.83 Hz), G3 (196.00 Hz), B3 (246.94 Hz), and E4 (329.63 Hz) at A4 = 440 Hz. However, this calculator does not generate audio — you would need a tone generator or digital tuner to produce reference tones.