Disclaimer: This post assumes you have some basic theory knowledge, know simple chords and at least a major scale in all modes.

It’s happened to all of us at some point… You’re getting together with some buddies to jam out some songs, your friend is telling you how a tune goes and says something like “The chorus is G, C, Em, Em9.”

Wait, what?

If you’ve studied theory for a couple years, this may be no problem. But for most guitarists, that will throw you for a loop.

Once you get beyond the basic major/minor chords, there are a lot of possibilities for what comes next. Just a few of them are…

6/m6

7/maj7/m7

9/maj9/m9

11/m11

13/maj13/m13

There are obviously way more possibilities, but by covering these to start, I think you’ll be on the right track. The trouble with these is, they’re generally presented in a single chord context. IE – here’s a C7 and this is how you play it. But if you don’t memorize where your fingers go, you’re out of luck. And relying on memorizing fingers gives you no ability to figure out other chords on your own.

Fundamentals

Let’s set some ground rules here, for the sake of these examples we’ll use C as our root. We’ll only cover one voicing/fingering for each chord as well – as that is a whole separate blog topic. And just to be clear, here’s our scale:

1 – C

2 – D

3 – E

4 – F

5 – G

6 – A

7 – B

For any basic level of theory knowledge, it’s not only important to be able to name the notes in a scale, but also sort out where they fit in a numerical sense. Associating numbers will make learning chords a ton easier as you’ll see the patterns involved.

Triads

This is some more basic information, but it is essential to know that all of the chords I referenced above (13 different ones) are built on a major or minor triad. That’s 1-3-5. You should know that already, but it’s still important to point out that this is the same foundation as you get into more confusing chords.

So for our example, all the major chords are built off of C-E-G. All the minor chords are built off of C-Eb-G.

Triads are easy, what next?

6 Chords

Let’s start with the easiest of the list, 6/m6. 6 chords are simply a major triad plus the 6th.

So C6 is… C-E-G-A.

m6? Same deal but change it to a minor triad.

Cm6 is C-Eb-G-A

7 Chords

Piece of cake, right? How about 7th chords? That’s where things get a little more confusing… the basic 7 chord still uses the major triad, but tricks you with a dominant 7th. That means, minor 7th. The maj7 is the same deal, but a major 7. m7 is just like m6, it’s the minor triad plus the 7 (dominant 7).

So the trick is whenever a chord say “maj” it’s referring to the 7. Otherwise, the 7 is dominant (minor).

C7 = C-E-G-Bb

Cmaj7 = C-E-G-B

Cm7 = C-Eb-G-Bb

I didn’t mention it in my original list, but the logic I just outlined would extend to something like Cm(maj7) and give you C-Eb-G-B

9/11/13 Chords

If you have everything down already, things get way easier than you might expect from this point on. 9/11/13 chords all use the 7 as the foundation, and keep adding from there. So the 9 is 1-3-5-7-9. 11 is 1-3-5-7-9-11. 13 is, you guessed it, 1-3-5-7-9-11-13 (yeah, 7 note scale, have fun with that). The major/minor triad rules still apply, and the 7 is dominant unless noted otherwise.

And for those a little more beginner level with their theory, you might get thrown by these numbers as there are only 7 notes in our scale… well, just keep counting. 8 is the octave up of the root, 9 is the octave up from 2, etc.

As for that impossible fingering I hinted at, that’s where things get fuzzy. In most cases, when you’re dealing with chords in the 9+ territory the triad gets hacked a bit. The 3 is generally the more important one as it will distinguish major/minor for you. But regardless, you can generally get the full triad in on a 9. 11 usually dumps the 5. 13 will usually lose the 3 & 5, maybe even the root.

Here are just a few examples for you.

C9

Cmaj9

Cm11

C13

Cmaj13

The Possibilities are Endless

These are just the basics really. There’s so much more, and hopefully this actually does help you understand chords on a systematic level. There are fairly easy rules to all of this and once you know a few of them, you can guess at a lot of the others.

Few random examples are:

add9 chords are a triad with an added 9. That means it does not include a 7. That goes for any “add” chord.

“Sus” chords are neither major or minor as they have no 3rd. The 3 gets replaced by whatever is noted in the “sus” part (2nd or 4th).

Augmented/Diminished chords refers to changes in the 5th. Aug = major triad with a raised (sharp) 5th. Dim = minor triad with a lowered (flat) 5th.

So now when you are learning a song and see C9sus4, you should be able to piece it together without searching for a chord chart.