Introduction
A major sixth is nine semitones — wide, warm, and consonant. It is the inversion of the minor third and shares some of that interval's emotional weight, but expanded outward. The major sixth is at the heart of "My Bonnie Lies Over the Ocean" and the love theme from countless film scores.
How to Find It on the Keyboard
Find any major sixth in two simple steps. The number tells you the letter. The semitones tell you the accidental.
- Start on any root note. Count 6 letter names (including the root) up the musical alphabet — that gives you the top letter.
- Now count exactly 9 semitones from the root. If the natural top letter is too high or too low, sharpen or flatten it to land on the right pitch.
- Use the explorer above to check yourself in all 12 keys. The two highlighted notes are the M6 from that root.
Quick check: from C, the M6 lands on A. From G, it lands on E. From E♭, it lands on C.
Hear It — Song Associations for Ear Training
The fastest way to internalise the major sixth is to associate it with a tune you already know. Sing the first two notes of any of these and you have the interval.
The Interval in Chords
Every chord is a stack of intervals. Here is where the major sixth shows up in common harmony.
| Chord | Name | How M6 Appears |
|---|---|---|
| C6 | Major 6th chord | Adds a major 6th to a major triad — bright, jazzy |
| Cm6 | Minor 6th chord | Adds a major 6th to a minor triad — Bond-theme color |
| C°7 | Diminished 7th | The d7 sounds like a major 6th enharmonically |
Inversion: Flip It Upside Down
When you move the bottom note up an octave (or the top note down an octave), the interval inverts. Two simple rules govern interval inversions:
- Numbers sum to 9. A 2nd inverts to a 7th, a 3rd inverts to a 6th, a 4th inverts to a 5th, and so on (1 + 8 = 9 for unison/octave).
- Quality flips. Major ↔ minor, augmented ↔ diminished, perfect stays perfect.
Compound Form
A compound interval is the same interval with an extra octave added on top. The character stays the same but the two notes are spread further apart. The compound form of the major sixth is the Major Thirteenth (M13) — 21 semitones in total.
Why it matters: chord extensions like 9ths, 11ths, and 13ths are compound intervals stacked above the basic triad. Move it up an octave and you get a wider, more open sound — common in piano voicings and orchestral spacing.
Enharmonic Equivalents
Two intervals are enharmonic when they sound the same but are spelled differently. Same physical pitches, different musical meaning.
- Diminished Seventh (d7) — nine semitones, e.g. C–B♭♭
On the keyboard, an enharmonic pair sounds identical. On paper, the spelling tells you which scale or chord the note belongs to — and that changes how it functions in the music.
Frequently Asked Questions
Why does a major sixth sound nostalgic?
It is wide and consonant, with a 5:3 ratio that produces a warm, open sound. The width gives it a "reaching" quality that registers as longing or memory.
What is the inversion?
A minor third. M6 + m3 = 9, major flips to minor.
How is the major sixth different from a diminished seventh?
They span the same nine semitones but are spelled differently. C–A is a major sixth; C–B♭♭ is a diminished seventh.
Where do major sixths appear in scales?
In every major scale, between the 1st and 6th degrees, and between the 3rd and 8th degrees.
How do I sing a major sixth?
Use "My Bon-nie" from "My Bonnie Lies Over the Ocean" — that opening leap is a major sixth.