Free Musical Notes Converter
Convert MIDI note numbers to frequencies (Hz) and note names instantly. Enter any MIDI number or frequency and get Scientific pitch, Solfège, Helmholtz, octave, and more. Free.
Exact Conversion Formula & Multipliers
Musical pitch conversion is governed by one internationally standardized reference: concert pitch A4 = 440 Hz, fixed by ISO 16:1975. From that anchor, any MIDI note number (n) converts to frequency via the equal-temperament formula: frequency = 440 × 2^((n − 69) / 12), where 69 is the MIDI number assigned to A4. This exponential relationship reflects how human pitch perception is logarithmic — each octave doubles the frequency, not adds a fixed amount.
Practical Real-World Scenarios
- Music production and synthesis: software synthesizers and samplers use MIDI note numbers internally, converting to frequency in Hz when precise oscillator tuning is required.
- Instrument tuning: electronic tuners display frequency in Hz, which musicians then relate to note names when tuning instruments to standard or alternate concert pitches.
- Audio engineering and acoustics: sound design and audio analysis work frequently in Hz for filtering and EQ, converting to musical note names when communicating with musicians rather than engineers.
Historical & Technical Background
Concert pitch varied significantly by region and era before the 20th century — orchestras in different European cities tuned A4 anywhere from roughly 415 Hz to 460 Hz, causing real complications for traveling musicians and instrument builders. The International Organization for Standardization formalized A4 = 440 Hz in 1955 (reaffirmed in 1975) specifically to end this fragmentation, though some orchestras today still deliberately tune slightly sharp (442–444 Hz) by tradition or preference, showing the standard is followed by convention rather than physical necessity.
Precision & Accuracy Statement
Frequencies use twelve-tone equal temperament with A4 = 440 Hz (ISO 16): f = 440 × 2^((n − 69)/12), with MIDI note 60 = C4 (middle C, Helmholtz c′). Results are shown to 10 significant digits. The wavelength assumes sound in dry air at 20 °C (343 m/s), a convention; the real value changes with temperature. Other tunings (for example A4 = 442 Hz or historical temperaments) give different frequencies.
How This Converter Works
MIDI maps notes to integers 0–127. Frequencies double with each octave. Enter a MIDI number or Hz frequency and instantly see the note name in Scientific, Solfège (Do-Re-Mi), and Helmholtz notation, plus octave, pitch class, and wavelength.
Common Conversions
| MIDI | Note | Frequency (Hz) | Scientific Pitch |
|---|---|---|---|
| 57 | A3 | 220.00 Hz | A below middle C |
| 60 | Middle C | 261.63 Hz | C₄ — universally referenced |
| 69 | Concert A | 440.00 Hz | A₄ — international tuning standard |
| 72 | C5 | 523.25 Hz | One octave above middle C |
| 84 | C6 | 1046.50 Hz | Two octaves above middle C |
| 127 | G9 | 12,543.85 Hz | Highest MIDI note |