4:5:6

4:5:6 is the classical major triad, also known as the Ptolemaic major triad. It has the lowest odd limit of all the JI triads, odd-limit 5.

Chord information

Harmonics	4:5:6
Subharmonics	1/(15:12:10)
Intervals from root	1/1–5/4–3/2
Cents from root	0¢–386¢–702¢
Step intervals	5/4, 6/5
Step cents	386¢, 316¢
Color name	yo or y
Prime limit	5
Genus	3⋅5 (15)
Intervallic odd limit	5
Otonal odd limit	5
Utonal odd limit	15
Consistent edos (d ≥ 2)	3edo*, 12edo*, 15edo*, 19edo**, …
* 2 ≤ d < 4; ** 4 ≤ d < 8; *** 8 ≤ d < 16; …

It is found on the I (1⁄1), IV (4⁄3), and V (3⁄2) of Ptolemy's intense diatonic scale (Zarlino), a very common 5-limit diatonic.

Common tetrads based on this triad (5-limit except where noted):

• 12:15:18:20 adds 5/3
• 8:10:12:15 adds 15/8
• 36:45:54:64 adds 16/9
• 20:25:30:36 adds 9/5
• 4:5:6:7 adds 7/4 (7-limit)
• 12:15:18:22 adds 11/6 (11-limit)