The Chord Calculator is a free utility to readers of The Essential Guitar Guide. To get the most out of the calculator, please review the instructions and notes below:
The window to the left displays the chord calculator in it's default state, set up to calculate a Cmaj chord.
To use the calculator, first select the root note of your chord, indicating whether you require the note to be sharpened or flattened by checking the relevant radio button. Setting the root note to B#, Cb, E# or Fb will generate an error message and the calculator will default back to the nearest valid note.
Next, specify the chord type by checking the relevant radio button. Note that the 1st and 2nd extension notes will blank out when selecting the Aug or Dim chord types. The 1st extension will default to 7 when selecting a Dom chord type, and a 4 when selecting a Sus chord type.
You may then specify the 1st extension to the chord (e.g, the 7 in Cmaj7). The 1st extension may contain a 2, 4, 6, 7, 9, 11, or 13 depending upon the chord type selected. If you have selected an extension that is meaningless to a certain chord type, the extension will default. You may only specify an extension of 2 or 4 when a Sus chord type is selected, and cannot set extensions of 1, 3, 5, 8, 10, 12 or anything greater than 13.
You cannot specify a 2nd extension when describing Sus chords, Aug chords or Dim chords (unless specifying a flattened fifth to describe a Diminished fifth chord), nor can you describe 2nd extensions without specifying a 1st extension (unless describing a Diminished Fifth). The calculator will also perform syntax checks on your chord description and correct any mistakes or invalid chord descriptions either during description or during calculation. Chords such as Cmaj11 with 9 as the 2nd extension will be reset to Cmaj11 during calculation since the 9 is redundant (an 11 chord will display the 9 and the 11th notes).
Note that you specify a Dom chord type when calculating chords that are actually written without a chord type, but do have at least 1 extension (don't confuse this with a chord simply written as 'C' - that refers to a Cmaj chord). For example, a Cmin7 chord is actually a C-minor-7 chord. A C7 chord is actually a C-dominant-7 chord. In music, we don't use the word 'dominant' and use the shorthand version instead. This also applies to C9, C11, C13 chords and altered chords such as C7#5, C7b9, C11b9 and C13#5.
You can use the calculator to describe virtually any chord you can think of. The example below describes a D#9#11 (D# dominant 9th augmented 11th) chord. One of the many uses of the chord calculator is for working out arpeggios and chord substitutions. If you look carefully at the notes displayed in the example below, you will see it contains the triad of an A#min chord (A# C# F) and the notes of an A#min/majth chord (A# C# F A). This means that you can use an A#min or A#min/maj7 chord or arepeggio containing these notes to comp over a D#9#11 chord.
When you have set the calculator to reflect your chord description, press the 'Display Chord Notes' button. You will see the notes that make up the described chord in the text box labelled 'Chord Notes'. The notes are displayed with the triad first (i.e., root, third, fifth) and extensions afterwards. If you have specified an extension greater than 7, every note will be displayed in order. For example, if you described a C11 chord, you will see the triad, plus the 7th note, the 9th note and the 11th note. This is harmonically correct in real terms, although you would not be able to play every note on the guitar due to the limited number of available strings and fingers.
The Chord Calculator does not compute polychords, (also know as slash chords), but working them out is very easy. A A/C# chord is simply an Amaj chord with an C# as the first bass note.
Whilst I have attempted to make the calculator as accurate as possible, there will be some altered chords that display the right note with the wrong enharmonic name. An example of this can be found when calculating a Cmaj7#9 chord. The notes that are returned for that chord description are C E G B Eb. Although the Eb note is correct, the strict key signiture would require that note to be referred to as a D#.
A six/nine chord (written 6/9) can be calculated if you describe the chord as a major 6th with an added 9th note.
'Add' chords can be calculated by describing a major chord with a 9th note as the 2nd extension, e.g., Cadd9 is really C major with the 2nd extension set to 9. Describing chords this way allows you to calculate add6, add9, add11 and add13 chords.
A Diminshed fifth chord can be described by specifying a chord type of 'Maj', no 1st extension and a flattened 5 as the 2nd extension. If you see the term 'undefined' in the Chord Notes display box, it means that you have tried to describe a new chord in the wrong order. If you work from the top down, this will rarely occur. To calculate the chord without this error, click the 'Display Chord Notes' button once again and the error should clear. If that fails, either describe the chord again, either with or without resetting the calculator with the 'Reset Calculator' button.
Copyright Dale Churchett © 1995. All Rights Reserved.