Here is a quick guide to chords in the key of Bb major.
| 1st | 2nd | 3rd | 4th | 5th | 6th | 7th |
| Major | Minor | Minor | Major | Major | Minor | Dim |
| I | ii | iii | IV | V | vi | viiº |
| Bb | Cm | Dm | Eb | F | Gm | Aº |
| A# | B# | C## | D# | E# | F## | G## |
The notes of an Bb major scale are:
| 1st | 2nd | 3rd | 4th | 5th | 6th | 7th |
| Bb | C | D | Eb | F | G | A |
Written as A# major, this would be:
| 1st | 2nd | 3rd | 4th | 5th | 6th | 7th |
| A# | B# | C## | D# | E# | F## | G## |
These two scales sound exactly the same, and so are ‘enharmonically equivalent’. The only difference is how they are written.
However, because of the improbable note names (double sharps, in particular), this version of the scale is more theoretical than practical, and would almost always be written as Bb.
Major Scale Formula
The scale notes above follow the 'major' scale formula of 'steps':
WHOLE – WHOLE – HALF – WHOLE – WHOLE – WHOLE – HALF
Or 'tones':
TONE – TONE – SEMITONE – TONE – TONE – TONE – SEMITONE
Or even frets:
Two Frets – Two Frets – One Fret – Two Frets – Two Frets – Two Frets – One Fret
Which gives us the following interval relationships from the tonic (1st note):
- Unison
- Major 2nd
- Major 3rd
- Perfect 4th
- Perfect 5th
- Major 6th
- Major 7th
- Octave
All the chords in the key of Bb major are made up of notes from the Bb major scale.
The notes of each chord in Bb major
| Chord Name | 1st | 3rd | 5th |
| Bb major | Bb | D | F |
| C minor | C | Eb | G |
| D minor | D | F | A |
| Eb major | Eb | G | Bb |
| F major | F | A | C |
| G minor | G | Bb | D |
| A diminished | A | C | Eb |
The relative minor scale of A#/Bb major is G minor, which comes from the 6th note of the Bb major scale.
