Hobbies Playing Music The Importance of the Third Interval Share PINTEREST Email Print Playing Music Playing Piano Tutorials Piano Chords Buying Advice Music Education Playing Guitar Home Recording By Brandy Kraemer Updated April 22, 2019 A third is an interval equal to three scale degrees that is most commonly major or minor*: Major Third (M3)Equal to four half steps; the distance between G—B is a major third. Minor Third (m3)Equal to three half steps; G—B♭ *By itself, the word "third" often refers to the major third (it’s common to omit the word ‘major’ when speaking of intervals, chords, and keys.) The Third as a Scale Degree This refers to the third note or chord on a musical scale. When reading or playing a scale, the third note will be the first clue as to whether that scale is major or minor. Compare the following G scales: G Major: G - A - B - C - D - E - F♯ G Minor: G - A - B♭ - C - D - E♭ - F The Role of the Third in Chords In many chord types, the third is an important building block. For example, major and minor chords are built similarly, except for their thirds: G Major TriadRoot Note: GMajor Third: BPerfect Fifth: D G Minor TriadRoot Note: GMinor Third: B♭Perfect Fifth: D