What Is a Major Third?

A major third is an interval of four half steps — C up to E, or A up to C♯. It's the interval that makes major chords sound major: bright, open, resolved. Shrink it by one half step and you get the darker minor third.

The shape on the fretboard

From a root on the low E or A string, the major third is one string up and one fret back:

On a single string it's four frets up. And it's baked into the guitar itself: the G and B strings are tuned a major third apart — the one exception in standard tuning that bends every shape crossing it.

Where you'll meet it

• Root + major third + perfect fifth = the major triad.
• The third is the note that answers "is this chord happy or sad?" — which is why chord-tone soloists target thirds above all.
• Ear anchors: the first two notes of "Oh, When the Saints" (more here).

The full comparison with its minor sibling is in Major Third vs Minor Third.

Related terms

• Minor third — one half step narrower
• Major triad — the chord it defines
• Interval shapes on the fretboard — the whole visual system