Basic Chord Theory
Chord FormulasWhat Makes a Chord?
Chord formulas refer to the actual notes being played in a chord and associates the numbers (1 through 8 ) of the major scale to those notes. Actually sometimes we repeat the scale an octave higher and continue counting up to number 13.
1 2 3 4 5 6 7 8 9 10 11 12 13... C D E F G A B C D E F G A...
Major Chords. For example, the C major chord is comprised of the notes C, E and G. When we look at the C major scale, we notice that these are notes numbered 1, 3, and 5. We then can deduce that the ‘chord formula’ of the major chord is 1,3,5. If we want to know the notes of any major chord, we can jump to that chord’s major scale and find notes 1,3,5 and know which notes we are playing. Thus the G chord is played by notes G, B, D. The D chord is comprised of notes D, F#, A. Etc.
Minor Chords. A minor chord takes the the 3rd note of the major chord and “flats” it, or lowers it a half step. It’s chord formula is 1,♭3,5. We can look at the C scale, and take the notes C, E♭, and G. ‘E’ is the 3rd note which gets “flatted”, and becomes an ‘E♭’ to make the Cm chord. The Dm is comprised of notes D,F,A.
Other Chord Variations. Sometimes we see chords like C2, Csus, C6, C7, Cm7, Cmaj7, Cmaj9, Cadd9, etc. These notations refer to special ways of handling the numbered notes of the chord’s major scale. Look at the following chart:
Chord Name Formula Notes Diagram
C2, Csus2 1,2,5 C,D,G x3x033 Csus, Csus4 1,4,5 C,F,G x33011 C6 1,3,5,6 C,E,G,A x32210 Cmaj7 1,3,5,7 C,E,G,B x32000 C7 1,3,5,b7 C,E,G,Bb x32310 Cadd9 1,3,5,9 C,E,G,D x32033
Click here for a much broader chart on chord formulas.
Look at the chart below to see the notes on the first four frets of the guitar. The sharped/flatted notes are left out to avoid clutter. But this chart can be used to modify the open chords you play, using the chord formulas in this section.
Click for PDF File
Hi,
how about diminished and augmented chord? How do you formulate it?
Thanks.
A diminished chord is 1 b3 b5, so Cdim would be C Eb Gb. Sometimes you will see a dim7 which would add bb7 (really the 6) so a Cdim7 would be C Eb Gb A.
An augmented is 1 3 #5, so a Caug would be C E G#.
Hi David,
I’m writing a website that dynamically generates chord charts based on fret and finger placements stored in a MySQL database. I generate the chord charts on-the-fly using JavaScript. I understand how to determine which notes need to be played (i.e. 1, 3, 5 of the scale, etc.) Do you know of a mathematical formula where, given a chord name, I could dynamically determine which strings/frets should be played and with which fingers? This way I could generate the chord chart for any chord based only on the chord name. I realize that a given chord might be played in several places on the fretboard, but for my purposes, I’d want the one closest to the nut.
Thanks….
I don’t have any other formulas other than what are on this page: http://titusvillebranchfellowship.org/guitar1/chords/chord-formulas/
As to how you would incorporate these into different algorithms is beyond me. You’d probably have to set up a different one for each type of variation, ie one for the sus2, one for the sus4, one for the 6th, one for the 7th, one for the maj7, etc.
Thanks for checking out my website. I hope it’s been helpful.
David
So now I know how to formulate chords, but how to know the strings that are not to be played in the formed chord? Like for example, in D chord 5th & 6th are not played.
Basically, as a general rule (but sometimes have to make exceptions), the lowest note (pitch) played in the chord is to be the root note (or the 1 note). That’s why the D chord is xx0232… bc that makes the D note as the lowest played. If we played it like this x00232, technically it becomes a D/A chord, or a D with the A in the bass. You can read my section on slash chords to understand them a little better. Let me know if I should try explain this better or differently. Thanks for checking out my web site. ~ David
Is there any formula that uses a “math equation” style. In other words, is there a formula where the fret number and string name can be used to show beginners the notes and chords easier rather than using the guitar alphabet? For example, say we take D Major since its the first chord that we learn in a guitar class. Wouldn’t it be easier to understand if the teacher wrote it:
D Major= A+D4+G5+B4+e
A bit of extra writing but it would simplify guitar chords a bit since we all already know how to add. That’s how they have it set up for video games like Mortal Kombat or Street Fighter; as a result, it’s easier to understand since some game guides use the actual button instead of the codes like HP or LK. It confuses so many beginners when it says that instead of saying the actual button on the control. Same with learning how to play guitar. It confuses many beginners when they hear C Minor or E Major or other chords like that. What I mean is, if there is a key or a legend from notes and chords to mathematical style equations, what is the name or where can I find this style?
If you read this entire thing, and respond to me about if such a method of learning notes and chords, I thank you SO much for your time.
Hi Patrick,
Wow. I’ve never heard of such a system. And quite, honestly, I’m not quite sure I understand the question and how your ‘D Major = A+D4+G5+B4+e’ relates to it. I don’t know if what you might be thinking would be in an expression like this for a D major chord: xx0232 where each place represents the strings (EADGBe) and the ‘x’ or number represents the fret number. I’m not sure this is what you are refering to however. Could you maybe pose your question another way?
Thanks, David
is it necessary for the root note to be on the lowest strings??
As a general rule yes. Sometimes it is not possible and so we might have to “cheat”. For example, many people play a Bm like this: xx4432. Here the lowest note played is F#. Also, if you’re playing with a band and you have a bass or keyboard player who is playing the low end notes, it’s not important.
can you teetch me how to defined the family chords???
I’m sorry Raymond. I do not understand your question.
Hi
I really appreciate this site. I am a self taught guitarist, which means I only copy what I see others are doing with regards to putting my fingers to the frets to form a chord without knowing how it arrived there. Now I know why. I feel I gained a lot in music through your site. Thanks so much.
Thanks for your encouraging feedback, Bernard.
Very helpful ! Thanks a lot ! If I were to leave out the 5 in a major 6 chord , I’d be playing 1-3-6. How would u name it ?
I would name it one of two ways, either C6(no 5), or Am/C.
I’m confused as to why the d chord is d f# a because if it’s 1,3,5 then surely it should be d f a.
To find the notes of any major chord, we must first start with the major scale of that chord. Because we are talking about the D chord, we start with the D major scale which is D E F# G A B C# D. Then we take notes 1,3,5 which are D F# and A.
actually i’m a Sri Lankan, I thank you for the effort that you are being done to give music knwladge for us .THis site really helped me a lot.So carry on what you are doing good luck.
thanks david…your lessons are really helpful….i just had a doubt, like when we want to find out the notes of a chord e.g. C ,we consider its major scale..then root out the 1st 3rd n 5th notes…and if we want a cmin chord we take 1st 3rdflat and 5th note from the c major scale…okay…but i was wondering why just the major scal?e…why the minor scale is not used? even when trying to figure out the family chords… i think we again use the major scale… does the minor scale have any role to play for these things? like what if you want to find the notes for gmin chord….or you want to know the major and minor family chords of gmin scale?
Hi Enoch,
We stick with the major for chord formulas, it’s kind of a standard. Adaptations could be made from minor scales and others. The downside to determining what chords would be in a minor key is that there are different minor scales: natural minor, harmonic minor and melodic minor. To me, the major scale seems easiest. If I’m playing in a minor key, I personally envision the major key (Em -> G) and then listen by ear for any variations. For example, in the key of Em, though it is technically 1 sharp, the key of G, sometimes the Bm is changed to a B major chord. But developing your ear can help with some of these variations.
David
PS – sorry for the late response.
thank u very much brother
The Roman numerals stand for the chords in a key. Arabic or regular numbers represent the NOTES in a chord. When looking for notes in a chord, find that chord’s major scale, number the notes, and take notes 1, 3, and 5. For G we get G A B C D E F# G. If we number these, then the notes in spots 1, 3 and 5 are the notes that make up the G major chord. These notes are G, B and D.
If, however, we are searching for the major chords in the key of G, we still use the G major scale, and number the notes. We look at the notes in spots 1, 4 and 5. These indicate which chords are major in the key of G. Chords G, C and D are major. And we use roman numerals when referring to them as chords: I, IV and V. Incidentally, 2, 3 and 6 indicate the chords that are minor in the key. So in the key of G, they would be Am, Bm and Em, and we number them with lowercase roman numerals, ii, iii, and vi.
Does this help?
David
Hi,
I’m confused with Chord Families (Major) where I, IV, V to be played.
But, in this page, you mention 1,3,5 as a Major Chord.
What are these two? pls explain.