Tool

The harmonic field of B♭ major

2 flats in the key signature. Click a degree to hear it, or hear the whole field.

Triads

DegreeSymbolNotesFunction
IBB♭ · D · FTonic
iiCmC · E♭ · GSubdominant
iiiDmD · F · ATonic
IVEE♭ · G · B♭Subdominant
VFF · A · CDominant
viGmG · B♭ · DTonic
vii°AdimA · C · E♭Dominant

Seventh chords

DegreeSymbolNotesFunction
Imaj7Bmaj7B♭ · D · F · ATonic
ii7Cm7C · E♭ · G · B♭Subdominant
iii7Dm7D · F · A · CTonic
IVmaj7Emaj7E♭ · G · B♭ · DSubdominant
V7F7F · A · C · E♭Dominant
vi7Gm7G · B♭ · D · FTonic
viiø7Am7♭5A · C · E♭ · GDominant

The notes are spelled in octave 4, from B♭4. 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.