Augmented triads (and all triads) in root position consist of an interval of a third from the root note to the "third," or middle note, and another interval of a third from the middle note ("third") to the top note, called the "fifth."

The other interval at play in a triad is the distance from the "root" to the "fifth," which is an interval of a fifth.

An interval of a third can be qualified as either major or minor.

A major third is four half steps, and a minor third is three half steps.

An interval of a "perfect" fifth is seven half steps, but an "augmented" fifth is eight half steps.

An augmented chord in root position (the root being the lowest note) is made up of an interval of a major third from the "root" to the "third," and another interval of a major third from the "third" to the "fifth." This means the distance is from the root to the fifth is one half step more than a "perfect" fifth, and so it is "augmented."

In the chart below the intervals are represented:

Major third = M3
Minor third = m3
Augmented fifth = A5