Harmonic Analysis Calculator

It means that chord's root note doesn't belong to the seven notes of the major scale built on your chosen key, so it falls outside the diatonic chords a key would normally generate — this describes borrowed chords, secondary dominants, and other chromatic harmony deliberately reaching outside the key for color or tension. A non-diatonic chord isn't a mistake in your progression; it's simply harmony the standard seven scale degrees can't label with a single Roman numeral.

This four-chord pattern, often called the 'pop-punk progression' or '4 chords' progression, has become one of the most widely used chord sequences in mainstream popular music across many genres and decades, which is reflected in the higher common-usage score this calculator assigns it. The score is a rough reflection of documented prevalence in popular songwriting, not a judgment about musical quality or which progression is objectively better.

It analyzes scale degrees using the major scale's interval pattern regardless of which key root you enter, so a minor-key progression will still get labeled with major-scale degree numbers rather than the minor scale's own natural degree relationships. For genuinely minor-key harmonic analysis, treat the degree numbers as relative to the major scale built on that same root, not as minor-key Roman numerals with their own distinct chord qualities.

It simply means your progression falls outside this calculator's short reference list of especially common patterns, not that it's incorrect or unusual — countless great progressions in jazz, classical, and other styles never appear on lists limited to the handful of sequences that dominate mainstream pop, rock, and blues. The individual scale degrees for each chord are still accurate and useful for understanding the progression's harmonic function even without a named-pattern match.