Chord Progression Calculator — Diatonic Chords for Any Key
Choose a key root (C through B) and mode (major or natural minor), then pick from 7 common progression patterns. The calculator instantly shows the correct diatonic chord names — major, minor or diminished — for every chord in the progression.
Key
Mode
Progression
How does this calculator work?
In a major key the 7 diatonic chord qualities are always I(M) ii(m) iii(m) IV(M) V(M) vi(m) vii°(dim); in natural minor: i(m) ii°(dim) III(M) iv(m) v(m) VI(M) VII(M). Select a key root, major or minor, and one of 7 common patterns (I–V–vi–IV, ii–V–I, etc.) to get the exact chord names for that key.
Formula
How this is calculated
A diatonic chord progression uses only chords built from notes that belong to the current key's scale. In a major key, stacking thirds on each of the seven scale degrees gives the chords: I (major), ii (minor), iii (minor), IV (major), V (major), vi (minor), vii° (diminished). These qualities are fixed by the major scale's interval structure — they do not change when you transpose to a different root, only the note names shift.
The natural minor scale has its own fixed pattern of chord qualities: i (minor), ii° (diminished), III (major), iv (minor), v (minor), VI (major), VII (major). The calculator builds the scale from the chosen root by adding the appropriate semitone offsets, then maps each Roman numeral in the chosen progression to its note name plus the fixed quality suffix.
Familiar naming conventions are used: uppercase Roman numerals for major chords (I, IV, V), lowercase for minor (ii, vi) and a degree symbol for diminished (vii°). The progression patterns range from a 3-chord blues (I–IV–V) to the ubiquitous pop axis (I–V–vi–IV), the jazz ii–V–I turnaround, and the Andalusian cadence often heard in flamenco and rock.
Frequently asked questions
The chord quality (major/minor/diminished) is determined by the intervals of the scale, not a free choice. In C major, the note E is the third scale degree; stacking thirds from E using only white keys gives E–G–B, which is a minor chord. From F they give F–A–C, a major chord. The pattern of qualities (M-m-m-M-M-m-dim) is the same in every major key — only the note names change.
Often called the "axis progression" or "pop progression", it is arguably the most common pattern in Western popular music (thousands of songs, from "Let It Be" to "Someone Like You"). In C major it gives C – G – Am – F. Its power comes from the strong resolution from V back to I and the relative minor vi providing emotional contrast.
Yes — borrowed chords, secondary dominants and modal mixture are all ways to add colour beyond strict diatonic progressions. This calculator shows only diatonic chords (strictly within the key) as a starting point. From here, a common move is to borrow the iv chord from the parallel minor (e.g. Fm in C major) for a darker colour on a beat that would normally be IV.
TG we-Calculate Editorial Team. (2026). Chord Progression Calculator — Diatonic Chords for Any Key [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/chord-progression-calculator
TG we-Calculate Editorial Team. "Chord Progression Calculator — Diatonic Chords for Any Key." TG we-Calculate. 2026. https://we-calculate.com/calculator/chord-progression-calculator.
TG we-Calculate Editorial Team, "Chord Progression Calculator — Diatonic Chords for Any Key," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/chord-progression-calculator
@misc{wecalculate_chord_progression_calculator, title = {Chord Progression Calculator — Diatonic Chords for Any Key}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/chord-progression-calculator}}, year = {2026}, note = {TG we-Calculate} }
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