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Blues Guitar Institute

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Chord Formulas: How to Quickly Multiply the Chords You Know

Lesson ID: TB213

I’m a big fan of chord formulas.

They are short strings of numbers – and a few symbols here and there – that help me remember the structure of a chord. Like this, 1 – 3 – 5, or this, 135. Learning formulas like these helped me multiply my chord vocabulary like nothing else. If you want to get deeper and really understand the chords that you’re playing, they can help you too.

We can use short formulas like 1 – 3 – 5 to communicate the structure of chords and the intervals that make them up. This approach not only saves time but also deepens your understanding of harmony and how chords relate to one another.

So today I’m going to break down:

  1. Why you need to know the major scale and its intervals to get the most from chord formulas
  2. How to use chord formulas to build basic three-note chords you’ll use all the time
  3. What happens when you tweak one note of the major triad
  4. How adding one note to the formula gives you a sophisticated sound, perfect for jazz and blues.

Ready? Let’s dive in.

Master the Major Scale to Understand Chord Formulas

Sure, you can master the major scale by memorizing tons of patterns on the fretboard. Helpful. But, there’s a better way. A way that’s based on the fundamental building blocks of melody and harmony:

Intervals.

Each note in the major scale has a name that refers to the interval it produces against the root.

If you haven’t spent some time learning the intervals and how to find them on the fretboard, I highly recommend it. Knowing the intervals and how to play them is a base layer skill that will help you make sense of the fretboard. I covered this in detail in this lesson:

Guitar Scales 101: Can You Play the Major Scale Anywhere on the Neck?

Here’s a quick recap of the intervals that make up the major scale:

Scale DegreeIntervalHalf Steps Above the Root
1Root0
2Major Second2
3Major Third4
4Major Fourth5
5Perfect Fifth7
6Major Sixth9
7Major Seventh11
8Octave12

If you know how to find the seven intervals in the chart above from any given root, you have the key to unlock the fretboard. This lesson on intervals can help you hone that crucial skill.

But how does this relate to chord formulas?

Well, chords are made by staking different intervals on top of each other. Chord formulas are a quick way to refer to the intervals that make up a chord.

Let’s see this in action with the most basic chord, triads.

Start Using Chord Formulas with Basic Triads

Triads are chords that have just three notes.

Stack the root, third, and fifth intervals from the major scale to form a major triad. Remember that we can label each interval in the major scale with a number which means that we can write the chord numerically like this:

1 – 3 – 5

This is the chord formula for the major triad. Let’s apply this formula to the key of C to build a C major triad.

Scale DegreeIntervalHalf Steps Above the RootNote
1Root0C
3Major Third4E
5Perfect Fifth7G
  • First, substitute the number “1” for a C note since C, is our root.
  • Replace “3” with the note a major third interval above C. Use the chart above and you’ll see you need to count up 4 half-steps for the major third. When you do, you’ll arrive at an E note.
  • Finally, for the “5” in the formula, count up 7 half-steps from the root and arrive at a G note.

Therefore, the notes of a C Major Chord are C, E and G.

Nice! Let’s do the same thing in the key of A.

Scale DegreeIntervalHalf Steps Above the RootNote
1Root0A
3Major Third4C♯
5Perfect Fifth7E

Now we’ve built an A Major chord – A, C♯, E

Yes, you could memorize the notes of every major chord. But why not develop the core skill of finding any interval on the fretboard and then combine intervals into chords using short formulas like, 1 – 3 – 5?

I love this approach. Practice finding intervals of the major scale on your guitar and test yourself by building major triads in different positions. Try different string sets too. Over time and with purposeful practice, this will become second nature.

Change the Formula and You Change the Chord.

Here’s where the formula way of thinking really starts to take off. We can change the major triad formula (1 – 3 – 5) to produce different types of chords.

For example, we can build a minor triad by changing one note. The minor triad formula is:

1 – b3 – 5

Notice the flat symbol ♭ in the formula – sometimes the the letter, “b” is used in place of the flat symbol.

Think of this as an adjustment to the interval from the major scale. The ♭ mark tells us to lower the major third by one half-step – one fret on the fretboard. Some chords contain an interval that’s raised by a half-step. The raised interval in the formula will have a sharp sign – “♯” or “#.”

The formulas for Minor, Augmented and Diminished Triads use these symbols in their formulas:

Minor Triad

  • Formula: 1-♭3-5
  • Example: A minor (A-C-E)

Augmented Triad

  • Formula: 1-3-♯5
  • Example: A augmented (A-C♯-E♯)

Diminished Triad

  • Formula: 1-♭3-♭5
  • Example: A diminished (A-C-E♭)

Maybe you’ve never actually played a diminished triad on your guitar. But armed with your ability to find the basic intervals along with the formula (1 – ♭3 – ♭5), I’ll bet you can find one.\

Try it!

Tweak One Note for Suspended Chords

If you’ve ever strummed along to Tom Petty’s tune, Free Fallin’, you’ve played a suspended chord.

Suspended chords, or “sus” chords, replace the third in a triad with either the second (Sus2) or fourth (Sus4) interval from the major scale.

These chords give an airy feeling to chords and are just one note away from the basic major triad. You can see this clearly in the formula for the Sus2 and Sus4 chords.

Sus2 Chord:

  • Formula: 1-2-5
  • Example: Asus2 (A-B-E)

Sus4 Chord:

  • Formula: 1-4-5
  • Example: Asus4 (A-D-E)

Tips for Using Sus Chords:

  • Try alternating between sus chords and their corresponding major triads
  • Use sus chords to melodically transition between chords
  • Incorporate sus chords into your strumming patterns for added variety

Add One Note to the Triad Stack for Jazzy and Bluesy Sounding Chords

Next, level up your chord game by adding one note to these three-note formulas. Adding some type of 7th interval, you can build Major 7th, Minor 7th and the very bluesy Dominant 7th chords.

Major 7th Chord:

  • Formula: 1-3-5-7
  • Example: CMaj7 (C-E-G-B)

The Major 7th chord has a dreamy quality that’s often used in jazz. To create a Major 7th chord, simply add the 7th scale degree to a major triad.

Minor 7th Chord:

  • Formula: 1-♭3-5-♭7
  • Example: Am7 (A-C-E-G)

Minor 7th chords have a smooth, mellow sound that shows up in many genre’s – you can hear it in this Keb’ Mo’ tune. Build a Minor 7th chord by adding a minor 7th scale degree to a minor triad.

Dominant 7th Chord:

  • Formula: 1-3-5-♭7
  • Example: C7 (C-E-G-B♭)

Dominant 7th chords used extensively in the Blues. To create a Dominant 7th chord, add the minor 7th scale degree to a major triad. More on Dominant 7th chords here.

Recap: Mastering Chord Formulas for Guitar

In this article, we covered:

  • The importance of understanding the major scale and its intervals
  • Building basic triads using chord formulas (major, minor, augmented, diminished)
  • Creating suspended chords by replacing the third with the second or fourth
  • Adding a fourth layer of harmony to create 7th chords (Major 7th, Minor 7th, Dominant 7th)

Practice finding intervals on the fretboard and applying chord formulas. It will help you understand the chords you already play and unlock new ones.

Play On!

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