A Major Triad

Chord Tones: A Major Triad

Symbol: M, maj, (none), Formula: 1-3-5

Chord Notation

Roman numeral (e.g. I, IV, V) and Nashville Number notation are key-dependent. See Keys pages for chord function within specific keys.

Inversions

Harmonic Function

The A major chord commonly functions as the submediant (vi) in C major or dominant (V) in D major. Its harmonic role varies by key, in major keys it provides stable harmonic grounding.

The major triad is the most fundamental chord in Western music, built from the root, major third, and perfect fifth. It has a bright, stable, and resolved sound. The A Major Triad specifically contains 3 notes: A, C♯, E (formula: 1-3-5). On guitar, A-rooted chords anchor to the open A string (5th string), and barre chord shapes rooted on A form the basis of the "A-shape" CAGED system. Blues, rock, and country music use A-rooted chords extensively, the classic 12-bar blues often starts on A, and many rock power chord riffs center on the open A string.

Common Progressions

The A Major Triad frequently appears in these progression patterns (shown in Roman numeral notation relative to key):

• I-IV-V-I-major
• I-V-vi-IV

Songs Featuring the Major Triad

Well-known songs where the A Major Triad, or this chord type, plays a prominent role:

• Let It Be – Beatles
• Don't Stop Believin' – Journey
• Imagine – John Lennon

Tuning Frequencies Across Temperaments

Frequencies shown at A=440 Hz. View full temperament data for any note.

Scales Containing the A Major Triad

These scales include the A Major Triad as a diatonic or characteristic chord: