The major third (M3) is one of the defining intervals of tonal harmony. It spans 4 semitones and gives major chords their bright, stable character.
Construction and spelling
M3 runs from a note to its third letter name, such as C to E, F to A, or D to F#. It belongs to the major/minor interval family. Correct spelling matters because it distinguishes major function from enharmonic alternatives.
Harmonic and melodic usage
Harmonically, M3 is the quality-defining interval in major triads. Melodically, it sounds open and consonant, often used to outline key center and chord identity. In voice leading, major thirds connect smoothly to related chord tones.
Examples
- Major triads built from root, major third, and perfect fifth
- Melodic motifs that outline tonic and dominant harmony
- Arpeggiated lines emphasizing bright tonal color
In practice
Practice M3 from multiple roots and sing it against a drone to hear its stable brightness. Compare M3 with m3 to internalize major versus minor quality. Strong M3 recognition improves chord hearing, intonation, and harmonic analysis.
