Just as we have formulas for scales we also have formulas for chords. Chords are built  from different scale degrees within the key that you’re working in. This is why it’s 

Just as we have formulas for scales we also have formulas for chords. Chords are built  from different scale degrees within the key that you’re working in. This is why it’s 

Just as we have formulas for scales we also have formulas for chords. Chords are built from different scale degrees within the key that you’re working in. This is why it’s important that you have an understanding of basic scale structure. If you haven’t viewed the lesson on Major diatonic scales do so now and then return here. Chords are built in upwards of 3 rds . A basic three note chord, called a triad, is built from the 1 st ,3 rd and 5 th degree of a scale. Taking a major 3 rd and stacking a minor 3 rd on top gives a major chord 1, 3, 5. Taking a minor 3 rd and stacking a major 3 rd on top gives a minor chord 1,3b,5. See figures 2a and 2b below.
Four note chords such as 6 th and 7 th chords are used to add a bit more color to the basic three­note triad or chord. You’ll see these type chords used a lot in modern blues and Jazz. The following list of chord formulas are the ones to learn first. Illustrated in C Major Major minor augmented diminished sus2 sus4 Major 7 Dominate 7 th minor 7 minor 7b5 diminished 7 Major 6 minor 6 1 3 5 (C E G) 1 3 5 (C E G) 1 3 5 (C E G ) 1 3 5 (C E G ) 1 2 5 (C D G) 1 4 5 (C F G) 1 3 5 7 (C E G B) 1 3 5 7 (C E G B ) 1 3 5 7 (C E G B ) 1 3 5 7 (C E G B ) 1 3 5 7(6) (C E G B or A) 1 3 5 6 (C E G A) 1 3 5 6 (C E G A) You can build any chord you want from the Major scale of the key that you’re in as long as you know the formula. Let’s take a look at the chords that make up the C Major Key.
Notes Function Function if in Root note key. I or 1 chord is C Maj C, E, G 1, 3, 5 II or 2 chord is Dm D, F, A 2, 4, 6 ( 1,3b,5 if in Dm) III or 3 chord is Em E, G, B 3, 5, 7 ( 1,3b,5 if in Em) IV or 4 chord is F Maj F, A, C 4, 6, 1 ( 1,3,5 if in F Maj) V or 5 chord is G Maj G, B, D 5, 7, 2 ( 1,3,5 if in G Maj) VI or 6 chord is Am A, C, E 6, 1, 3 ( 1,3b,5 if in Am) VII or 7 chord is B dim B, D, F 7, 2, 4 ( 1,3b,5b if in B dim) All these chords are diatonic to the scale of C Major and are considered diatonic chords. Notice how the note functions are different between the key of C Major and if the chords were in there own Key. Example: D, F, A note functions in the key of C Major are 2,4,6, or the Dm chord. However if you were in the key of D minor the notes D,F,A would be 1,3b.5. Let’s look at another example of how we can build any chord from a Major scale. Let’s say we want to build the chord A min 7. The first step would be to write out the A major scale. A Major A, B, C#, D, E, F#, G# Function 1 2 3 4 5 6 7 Maj Formula w w h w w w Second we know that a min 7 th chord is built using the formula 1 ,3 b , 5 7 b We have to flat the 3 rd and 7 th of the A Major scale so the notes would be A, C, E, and G. The C# becomes C and the G# becomes G. that’s really all there is to it. You can write out any chord this way. Let’s take a look at root 6 and root 5 bar chords and how they are made up. In the following example we’ll start off with root 6 bar chords. Root 6 bar chords have the open E shape that is moveable up and down the neck of the guitar. See the following diagrams.
The numbers in the circles now indicate the chord formula. Open E Major 1 5 1 3 5 1 A Major root 6 bar chord 1 5 1 3 5 1 You can see the outline in red of the open E shape chord. Notice the formula for the 6­ note chord. It’s 1,5,1,3,5,1 the same as the open E only now you have an A Major chord. Say you want to make this chord a minor chord. You know the formula for minor chords is 1,3 b , 5, so just flat the 3 rd . A minor root 6 bar chord 1 5 1 3 b 5 1 Let’s take a look at root 5 bar chords. These chords are based on the open A shape. The 6 th string or open E string is not used with root 5 bar chords.
Open A Major 1 5 1 3 5 C Major root 5 bar chord 1 5 1 3 5 So if we want to make this a minor chord, all we do is flat the 3 rd . C minor root 5 bar chord 1 5 1 3 b 5 Let’s make it a C 6 th chord C 6 th root 5 bar chord 1 3 5 6 You can see how important it is to know your chord formulas and the numbering system. With it you can build any chord