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 A I Tonic Diatonic B m ii Subdominant Diatonic C ♯ m iii Tonic Diatonic D IV Subdominant Diatonic E V Dominant Diatonic F ♯ m vi Tonic Diatonic G ♯ dim vii° Dominant Diatonic
Degree Symbol Notes Function I A A · C♯ · E Tonic ii B m B · D · F♯ Subdominant iii C ♯ m C♯ · E · G♯ Tonic IV D D · F♯ · A Subdominant V E E · G♯ · B Dominant vi F ♯ m F♯ · A · C♯ Tonic vii° G ♯ dim G♯ · B · D Dominant
Seventh chords A maj7 Imaj7 Tonic Diatonic B m7 ii7 Subdominant Diatonic C ♯ m7 iii7 Tonic Diatonic D maj7 IVmaj7 Subdominant Diatonic E 7 V7 Dominant Diatonic F ♯ m7 vi7 Tonic Diatonic G ♯ m7 ♭5 viiø7 Dominant Diatonic
Degree Symbol Notes Function Imaj7 A maj7 A · C♯ · E · G♯ Tonic ii7 B m7 B · D · F♯ · A Subdominant iii7 C ♯ m7 C♯ · E · G♯ · B Tonic IVmaj7 D maj7 D · F♯ · A · C♯ Subdominant V7 E 7 E · G♯ · B · D Dominant vi7 F ♯ m7 F♯ · A · C♯ · E Tonic viiø7 G ♯ m7 ♭5 G♯ · 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.
Related keys F♯ minor Relative: the same key signature, in the other mode. A minor Parallel: the same tonic, in the other mode. A in the dictionary The tonic triad: notes, staff, keyboard and guitar shapes. Read about Diatonic harmony The chords that arise from stacking thirds on each degree of a scale, and why each quality lands where it does. Harmonic function The role each degree plays — tonic, subdominant, or dominant — and the tension that moves one to the next. Roman numeral analysis The notation that describes a chord by the position it occupies in the key rather than by the note it sits on. Minor key harmony The minor harmonic field, which is not one field: the three minor scales produce different chords on the same degree. 
