Scale & Chord Harmonizer

Explore how chords are constructed by harmonizing scale degrees across keys and modes.
What is Harmonizing a Scale? (Click to toggle guide)

Harmonizing a scale means building a chord on each scale degree using only the notes belonging to that scale. By taking a note (the Root), skipping the next scale note, taking the next one (the Third), skipping the next, and taking the next (the Fifth), we stack thirds to build a three-note chord called a Triad. Stacking one more third (the Seventh) creates a 7th Chord.

This interactive tool shows you exactly which chords belong to which keys, maps them visually on a note wheel, a piano, and a fretboard, and lets you play them to hear their character.

Harmonized Degrees

Hover over a row to highlight its chord on the visualizers. Click "Play Chord" to hear it.
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Chromatic Note Wheel

Root Note
In Scale
In Active Chord

Circle of 5ths Diagram

Visualizes 5th key relationships and neighboring trad key modes.

Root Key
Diatonic Scale Note
Active Chord Note
Fretboard Instrument & Tuning:
Root Note
In Scale
In Active Chord

Understanding Modal Chords in Folk Music

What is a "Mode"?

A mode is a permutation of the major scale. If you play the notes of the **C Major scale** starting on **C**, you are in the **Ionian mode (Major)**. But if you play the exact same notes (no sharps, no flats) starting on **D**, you are playing in **D Dorian**. Because the home note (tonic) has shifted to D, the intervals change, creating a minor, mysterious sound.

Irish Traditional Modes

Traditional Irish tunes are modal. You will frequently encounter:

  • Major (Ionian): Happy, bright. e.g. Cooley's Reel (G major).
  • Mixolydian: Major-like, but with a flattened 7th (b7) giving a bluesy or bagpipe-like feel. e.g. The Morrison's Jig (E Mixolydian).
  • Dorian: Minor-like, but with a raised 6th note, creating a haunting, driving sound. e.g. Drowsy Maggie (E Dorian).
  • Aeolian (Natural Minor): Sad, dark, and soft. e.g. The Star of Munster (A Aeolian).

Modal Chord Functions

Accompanists (guitar/bouzouki players) use modes to find chord substitutions. For example, in **D Dorian** (which uses the notes of C Major), the major IV chord is **G Major**, and the flattened 7th chord is **C Major**. Accompanying a Dorian tune using standard minor scale chords (like A minor or G minor) would clash, because the raised 6th note of Dorian dictates a G Major chord!