What Is A Triad?
A triad is a chord made from three notes: a root note, a 3rd and a 5th. What type of triad it is (major, minor, diminished or augmented) depends on the distances between those three notes, which we measure in semitones - the smallest step on a piano, from one key to the very next key, whether it is black or white.
Method 1: The Formula
Every root position triad can be built with a formula of the form 'X +a Y +b Z', where X is the root note, Y is the middle note (the 3rd) and Z is the highest note (the 5th), and the numbers are how many semitones to count up between them. There are four formulas, one for each type of triad. Each animation here builds the chord starting on C. They play automatically without sound - press 'Play Audio' to restart one and hear it once through.
C Major: X +4 Y +3 Z
Count up 4 semitones from the root to reach the 3rd, then 3 more to reach the 5th.
C Minor: X +3 Y +4 Z
The same two gaps in the opposite order: 3 semitones to the 3rd, then 4 more to the 5th. The smaller first gap is what makes the chord sound minor.
C Diminished: X +3 Y +3 Z
Two gaps of 3 semitones, which squeezes the 5th down to just 6 semitones above the root.
C Augmented: X +4 Y +4 Z
Two gaps of 4 semitones, which stretches the 5th up to 8 semitones above the root.
Alternative Methods For Major And Minor Triads
Using key signatures / scales: every major or minor chord is the first diatonic chord (I or i) of the key with the same root note and tonality (see 'Diatonic Chord Charts'). Limit yourself to only the notes of that scale, then 'play a note, miss a note, play a note, miss a note, play a note' - or in other words, play the 1st, 3rd and 5th notes of the scale.
Using alternative key signatures: the same chord is also a diatonic chord in several other keys, for example C Major is the 4th chord (IV) in the key of G Major. If you are more comfortable with major scales, limit yourself to the notes of one of those keys, begin on the root of the chord and play a note, miss a note, play a note, miss a note, play a note.
Alternative Method For Diminished Triads
A diminished triad is always the 7th diatonic chord (viidim) of one major key (for example B diminished in the key of C Major) and the 2nd diatonic chord (iidim) of one minor key. Limit yourself to the notes of that scale, begin on the root of the chord and play a note, miss a note, play a note, miss a note, play a note.
Augmented Triads
Augmented triads are not diatonic chords of any major or natural minor scale, so the formula is the way to build them.
