Data schema
ChordMetric stores pitch classes as integers from 0 to 11 and written notes as a letter plus accidental. Chord qualities store semitone intervals, diatonic degrees, interval names, symbols and formulas. Scale types store semitone intervals and explicit parent-degree letter steps, so pentatonic scales do not inherit a false consecutive-letter rule.
Pitch class and spelling
Sounding pitch and written function are separate fields. A pitch class locates a key in the equal-temperament octave; a spelling identifies the letter and accidental required by the chord, scale or interval. Enharmonic notes can share pitch class without becoming interchangeable theoretical answers.
Frequency and generated audio
Frequency uses 440 × 2^((midi − 69)/12), with A4 at MIDI 69. Playback is created on demand with browser oscillators, begins only after user action and can be stopped. ChordMetric includes no sampled commercial recordings, MIDI files, songs or backing tracks.
Chord and inversion method
Each chord quality combines degree roles with target semitone offsets. Letter names follow the degree number before accidentals are calculated. Inversion rotates the ordered chord tones and reports the new bass; it does not claim one required voicing.
Scale and chromatic method
Seven-note major and minor forms use consecutive degree letters. Major pentatonic uses 1, 2, 3, 5 and 6; minor pentatonic uses 1, ♭3, 4, 5 and ♭7. Chromatic output is a separately labelled directional convention: ascending prefers sharps and descending prefers flats, with context-dependent exceptions acknowledged.
Reverse identification
The finder compares unique pitch-class sets. Exact-set identities are separated from partial supersets. A specified bass can describe inversion, while ambiguous or incomplete sets remain labelled as interpretations rather than a single guaranteed name.
Accuracy approach
ChordMetric states its tuning and spelling conventions, checks representative chords, scales, intervals and inversions, and compares the results with the sources listed below.
Sources
ChordMetric uses established equal-temperament mathematics and conventional theory definitions. The named references below support the conventions described here and do not imply endorsement.
Source ledger — checked 28 August 2026
Hybrid Pedagogy Publishing, “Open Music Theory: Scales and scale degrees”, https://openmusictheory.github.io/scales.html — supports whole/half-step definitions, major and natural-minor patterns, harmonic-minor alteration and classical melodic-minor direction. Hybrid Pedagogy Publishing, “Triads and seventh chords”, https://openmusictheory.github.io/triads.html — supports triad interval qualities, lead-sheet symbols, inversions and diatonic Roman-numeral patterns.
Hybrid Pedagogy Publishing, “Intervals and dyads”, https://openmusictheory.github.io/intervals.html — supports the combined letter-count and semitone method, qualities and inversion relationships. Hybrid Pedagogy Publishing, “Key signatures”, https://openmusictheory.github.io/keySignatures.html — supports signature and relative-key relationships. The MIDI Association, “Microtuning and Alternative Intonation Systems”, https://midi.org/microtuning-and-alternative-intonation-systems — supports MIDI note 69 mapped to A at 440 Hz. W3C, “Web Audio API 1.1”, https://www.w3.org/TR/webaudio/ — supports browser oscillator synthesis and audio-node routing.
Copyright and corrections
Explanations, diagrams and generated tones are original to ChordMetric. The site does not reproduce songs, lyrics, sheet music, third-party MIDI or sampled recordings. Report a material theory or spelling error through the Corrections page so related answers can be reviewed together.