A 4/5 chord is the 4th chord in a major key, with the 5th note in the bass.
A 4/5 chord in the key of D Major would be G/A.
The enharmonic spelling is an 11 chord (chord construction). For example:
G/A = A G B D
A11 = A G B D (leaving out C# and E, the third and fifth of the chord)
A 4/5 chord is not used as a substitute for a 4 chord, as one might think. It is actually a substitute for a 5 chord. For example:
Instead of using an Asus chord in the key of D, one might use an A11 or G/A which still contains the sus (the 11) but also contains a dominant seventh and a ninth. Now that is a big thick chord!!
A 4/5 chord is complex sounding, and a really great tool for a Guitar Thinker. Four over five chords are actually more common than you might think!
It is quite useable in pop music. If you have ever listened to James Taylor, you will recognize this chord immediately. He used it all the time.
Here is a chart of common keys and their corresponding 4/5 chords. I hope it is helpful.
A Major – 4/5 in this key is D/E
C Major – 4/5 in this key is F/G
D Major – 4/5 in this key is G/A (see example above)
E Major – 4/5 in this key is A/B
G Major – 4/5 in this key is C/D
Nate Dean is a session guitarist, arranger, Worship leader, and songwriter. He has played on hundreds of recording sessions in both Nashville and his hometown Kansas City.