Let’s say you come across a new chord, and you don’t have a published shape for it to hand. We’ll take an utterly crazy example chord to show that this works in all situations: G#m7(#5). Either our musical theory knowledge or a quick glance at the chord theory page shows us that a minor seventh (m7) chord is made up of the root, minor third, fifth and dominant seventh.

Referring to the tables in the music theory page if necessary, we determine that, for G#m7, these notes are G#, B, D# and F#. The (#5) in the chord name indicates that the fifth is to be sharpened a semitone to Dx (D double-sharp), which is the same as E on a guitar.

So how do we work out a finger pattern? Let’s draw a grid and put marks where notes in this chord lie:

   0   1   2   3   4   5   6
E  |---|-x-|---|-x-|---|---| E F# G#
B  |---|---|---|---|-x-|---| B E
G  |-x-|---|---|-x-|---|---| G# B
D  |---|-x-|---|-x-|---|-x-| E F# G#
A  |---|-x-|---|---|---|---| B
E  |---|---|---|-x-|---|---| G#

Here, an -x- marks a potential finger position. We want to ensure as many notes from the chord as possible are present: if notes are omitted, the chord can become ambiguous and not sound as intended.

Now we need to work out a compromise between easy fingering and including the important notes in the chord (arguably, all of them!). Looking at the grid above, the most obvious shape is this:

   3   4   5   6   7         
E  |(1)|---|---|---| G#
B  |---|-2-|---|---| E (=Dx)
G  |(1)|---|---|---| B
D  |(1)|---|---|---| F#
A X|---|---|---|---| 
E  |(1)|---|---|---| G#

Note that we start on fret 3 now, not the nut, and that the A string is not played. In the absence of a bass player, I’d probably pluck the bottom string with my thumb; if I had a bassist or someone else playing the low G#, I’d probably just strum the top four strings. As this does not use any open strings, it can be used anywhere on the neck for arbitrary m7(#5) chords.

That’s an extreme example of a very complex chord that you are unlikely to ever need—unless you need to play the Bee Gees’ I Could Not Love You More. Here are some simpler “real-world” examples:

Amaj9

The chord theory page tells us that this is root, third, fifth, major seventh and ninth, and conveniently provides the notes: A-C#-E-G#-B. The first thing to notice is that three of these notes correspond to open strings.

Let’s assume a five-string chord, starting on the open A string, as a variant of the standard A chord. As this could be simple, let’s work it out without the chart. Working up from the open A string, there’s an E on the second fret of the D string, a G# on the first fret of the G, and the B and E can be left open. That gives us:

   0   1   2   3   4    
E O|---|---|---|---| E
B O|---|---|---|---| B
G  |-1-|---|---|---| G#
D  |---|-2-|---|---| E
A O|---|---|---|---| A
E X|---|---|---|---|

Pretty easy to finger. The disadvantage is that it omits the third (C#), which gives the chord its major feel. In practice, this doesn’t really affect things. If you were really bothered about this, you could soon work out:

   4   5   6   7   8    
E  |---|---|-4-|---| B 
B  |-1-|---|---|---| E 
G  |---|-3-|---|---| C#
D  |---|-2-|---|---| G#
A O|---|---|---|---| A
E X|---|---|---|---|

This is a bit harder to finger, but includes all the notes.

Dmaj7/G

We’ll start from the basic open D chord that most people know:

   0   1   2   3   4    
E  |---|-2-|---|---| F#
B  |---|---|-3-|---| D
G  |---|-1-|---|---| A
D O|---|---|---|---| D
A X|---|---|---|---| 
E X|---|---|---|---|

Turning this into a Dmaj7 chord requires a C# (see chord theory page if necessary). It’s easy to see what to do here:

   0   1   2   3   4    
E  |---|-3-|---|---| F#
B  |---|-2-|---|---| C#
G  |---|-1-|---|---| A
D O|---|---|---|---| D
A X|---|---|---|---| 
E X|---|---|---|---|

OK—now we need to get a G in the bass. We could turn this into a three-string chord without the open D and with an open G string, but that would be a weak-sounding chord. The lowest G is the third fret of the low E string, although it’d be hard to get a finger there from the shape above. The solution is to use a partial bar:

   0   1   2   3   4    
E  |---|(1)|---|---| F#
B  |---|(1)|---|---| C#
G  |---|(1)|---|---| A
D O|---|---|---|---| D
A X|---|---|---|---| 
E  |---|---|-3-|---| G

The A string is not played here—I use my right thumb to pluck the string whilst strumming the top four with my fingers. The A could theoretically be played open, but the small interval (tone) between the low G and low A would give a very muddy sound.

Ebsus4

Eb is awkward with standard tuning. The standard E-shape for Eb major (without the sus4) would need the bar at fret 11, which is highly impractical for general use. The A-shape is at fret 6, so let’s try that.

   5   6   7   8   9    
E  |(1)|---|---|---| Bb
B  |---|---|-4-|---| G
G  |---|---|-3-|---| Eb
D  |---|---|-2-|---| Bb
A  |(1)|---|---|---| Eb 
E X|---|---|---|---|

The sus4 replaces the major third (G) with the fourth (Ab). There’s only one G in the chord above, so to go up a semitone is pretty easy.

   5   6   7   8   9    
E  |(1)|---|---|---| Bb
B  |---|---|---|-4-| Ab
G  |---|---|-3-|---| Eb
D  |---|---|-2-|---| Bb
A  |(1)|---|---|---| Eb 
E X|---|---|---|---|

An alternative for long-fingered players would be to turn the open D into a four-string Eb:

   0   1   2   3   4    
E  |---|---|-3-|---| G
B  |---|---|---|-4-| Eb
G  |---|---|-2-|---| Bb 
D  |-1-|---|---|---| Eb
A X|---|---|---|---| 
E X|---|---|---|---|

…and raise the G as above:

   0   1   2   3   4    
E  |---|---|---|-4-| Ab
B  |---|---|---|-3-| Eb
G  |---|---|-2-|---| Bb 
D  |-1-|---|---|---| Eb
A X|---|---|---|---| 
E X|---|---|---|---|

Cm6/Eb

This isn’t even close to a standard chord, so we’ll have to start from scratch. Cm6 is C-Eb-G-A, and we want the first inversion with the Eb as the lowest note.

Let’s mark out possible finger positions again:

   0   1   2   3   4   5   6   7   8
E  |---|---|-x-|---|-x-|---|---|-x-| G A C
B  |-x-|---|---|-x-|---|---|---|-x-| C Eb G
G  |---|-x-|---|---|-x-|---|---|-x-| G A C Eb
D  |-x-|---|---|---|-x-|---|-x-|---| Eb G A
A  |---|---|-x-|---|---|-x-|---|---| A C Eb
E  |---|---|-x-|---|-x-|---|---|-x-| G A C

The bottom E string is no use, as an Eb in the bass would be on fret 11. I’d try this for a bar chord:

   4   5   6   7   8    
E  |(1)|---|---|---| A
B  |---|---|---|-4-| G
G  |(1)|---|---|---| C
D  |(1)|---|---|---| G
A  |---|-2-|---|---| Eb
E X|---|---|---|---|

Again, as a bar chord, this can be used for any m6 first inversion.

A four-string version of the chord is:

   0   1   2   3   4    
E  |---|---|-4-|---| G
B  |-2-|---|---|---| C
G  |---|-3-|---|---| A
D  |-1-|---|---|---| Eb
A X|---|---|---|---|
E X|---|---|---|---|

Like the standard F chord, this is not a bar chord (no bar) but it also isn’t an open chord (no open strings), so it can also be used in any position.