Tool

The harmonic field of A major

3 sharps in the key signature. Click a degree to hear it, or hear the whole field.

Triads

DegreeSymbolNotesFunction
IAA · C♯ · ETonic
iiBmB · D · F♯Subdominant
iiiCmC♯ · E · G♯Tonic
IVDD · F♯ · ASubdominant
VEE · G♯ · BDominant
viFmF♯ · A · C♯Tonic
vii°GdimG♯ · B · DDominant

Seventh chords

DegreeSymbolNotesFunction
Imaj7Amaj7A · C♯ · E · G♯Tonic
ii7Bm7B · D · F♯ · ASubdominant
iii7Cm7C♯ · E · G♯ · BTonic
IVmaj7Dmaj7D · F♯ · A · C♯Subdominant
V7E7E · G♯ · B · DDominant
vi7Fm7F♯ · A · C♯ · ETonic
viiø7Gm7♭5G♯ · B · D · F♯Dominant

The notes are spelled in octave 4, from A4. The function is assigned by degree — tonic on I, III and VI; subdominant on II and IV; dominant on V and VII — which is how the harmonic field is taught. Context can change that reading, and the tool reports the degree.