|Other instruments||Bass guitar|
|Advantages||Closely approximates standard tuning|
|Disadvantages||Difficult to play conventional music|
|Left-handed tuning||All-fifths tuning|
|Jazz musician Stanley Jordan stated that all-fourths tuning "simplifies the fingerboard, making it logical".|
|Regular tunings (semitones)|
|Minor thirds (3)|
|Major thirds (4)|
|All fourths (5)|
|Augmented fourths (6)|
|New standard (7, 3)|
|All fifths (7)|
|Minor sixths (8)|
Among alternative tunings for the guitar, all-fourths tuning is a regular tuning. In contrast, the standard tuning has one irregularity--a major third between the third and second strings--while having perfect fourths between the other successive strings. The standard tuning's irregular major-third is replaced by a perfect fourth in all-fourths tuning, which has the open notes E2-A2-D3-G3-C4-F4.
Among regular tunings, this all-fourths tuning best approximates the standard tuning.
In all guitar tunings, the higher-octave version of a chord can be found by translating a chord by twelve frets higher along the fretboard. In every regular tuning, for example in all-fourths tuning, chords and intervals can be moved also diagonally. For all-fourths tuning, all twelve major chords (in the first or open positions) are generated by two chords, the open F major chord and the D major chord. The regularity of chord-patterns reduces the number of finger positions that need to be memorized. Jazz musician Stanley Jordan plays guitar in all-fourths tuning; he has stated that all-fourths tuning "simplifies the fingerboard, making it logical".
Among all regular tunings, all-fourths tuning E-A-D-G-C-F is the best approximation of standard tuning, which is more popular. An advantage of standard tuning is that it has many six-string chords, unlike all-fourths tuning. All-fourths tuning is traditionally used for the bass guitar; it is also used for the bajo sexto.
All-fourths tuning is closely related to all-fifths tuning. All-fourths tuning is based on the perfect fourth (five semitones), and all-fifths tuning is based on the perfect fifth (seven semitones). These perfect-fourth and perfect-fifth intervals are termed "inverse" intervals in music theory, and the chords of all-fourth and all-fifths are paired as inverted chords. Consequently, chord charts for all-fifths tunings may be used for left-handed all-fourths tuning.
Sethares, Bill (2001). "Regular tunings". Alternate tuning guide (pdf). Madison, Wisconsin: University of Wisconsin; Department of Electrical Engineering. pp. 52-67. 2010 Alternate tuning guide, including a revised chapter on regular tunings. Retrieved 2012.