Chord Progression Generator

How the Chord Progression Generator Works

This tool builds diatonic chord progressions in any key. Choose a key (C, D, E flat, and so on), pick major or natural minor, and select a Roman-numeral pattern such as I–V–vi–IV. The generator instantly names the chords and also lists all seven diatonic chords of the key so you can experiment with your own progressions.

The Formula

A major scale is built from a fixed step pattern of whole and half steps (W-W-H-W-W-W-H), giving seven notes. Stacking thirds on each note produces the seven diatonic triads, and those triads always follow the same quality pattern:

Major key: I ii iii IV V vi vii°
Minor key: i ii° III iv v VI VII

Each Roman numeral points to a scale degree. The generator finds that degree’s note in your chosen key and attaches the correct quality (major, minor or diminished). Because the pattern is fixed, the same numeral set transposes perfectly to every key.

Worked Example

In the key of C major with the pop progression I–V–vi–IV:

• I is the 1st degree, major → C
• V is the 5th degree, major → G
• vi is the 6th degree, minor → Am
• IV is the 4th degree, major → F

So I–V–vi–IV in C major is C – G – Am – F. Switch the key to G and the very same pattern becomes G – D – Em – C.

Diatonic Chords by Scale

Roman	Major quality	Minor quality
1	I major	i minor
2	ii minor	ii° diminished
3	iii minor	III major
4	IV major	iv minor
5	V major	v minor
6	vi minor	VI major
7	vii° diminished	VII major

Why Roman Numerals Help

Writing progressions in Roman numerals keeps them key-independent. A songwriter who learns I–V–vi–IV can instantly play it in any key by reading the chord table. This is why so many hit songs share the same numeral pattern even though they sound different — they are simply the same progression transposed to a new key.