Dominant 7th Chord Formula: 1-3-5-b7 Explained

The dominant 7th chord formula is 1–3–5–♭7: a root, major third, perfect fifth, and minor seventh. For example, C7 contains C–E–G–B♭. This four-note chord combines a major triad with a lowered seventh, producing the tension heard in blues, jazz, rock, and V7–I progressions.

Understanding the formula is more useful than memorizing isolated shapes. Once you know the intervals, you can spell a dominant seventh chord from any root, recognize its symbol, and see why it often resolves so convincingly.

What Is the Dominant 7th Chord Formula?

A dominant seventh chord uses 1–3–5–♭7. Measured upward from the root, those notes sit at 0, 4, 7, and 10 semitones. Another way to describe the structure is a major third, minor third, and minor third stacked in sequence.

Chord tone	Interval above root	Semitones above root	Note in C7
1	Root	0	C
3	Major third	4	E
5	Perfect fifth	7	G
♭7	Minor seventh	10	B♭

The first three tones form a major triad. If that part of the construction is unfamiliar, start with the major chord formula before adding the seventh.

The chord symbol is normally the root name followed by 7: C7, F7, B♭7, or F♯7. The plain “7” means dominant seventh quality; it does not mean major seventh. Symbols such as Cmaj7 and Cm7 identify different seventh-chord qualities.

How Do You Build a Dominant 7th Chord?

Build a dominant seventh chord by forming a major triad on the chosen root, then adding a note a minor seventh above that root. You can use scale degrees or count semitones, but the written note letters must also be correct.

Start with a major triad

Choose a root, then add its major third and perfect fifth. To build G7, begin with G. Four semitones above G is B, and seven semitones above G is D, giving G–B–D. The interval roles are easier to recognize when you understand how chords are built from scale degrees.

Add the minor seventh

Count 10 semitones above the root or find the seventh note letter and lower it by one semitone from the major seventh. The seventh letter above G is F, and F is already 10 semitones above G, so G7 is G–B–D–F.

The ♭ in ♭7 describes a lowered scale degree, not a requirement that the note’s written name contain a flat. In D7, the ♭7 is C natural, not C♭, because D–C is a minor seventh. In F♯7, the ♭7 is E natural. Correct chord-note spelling keeps each letter name represented once: root, third, fifth, and seventh.

Here is the same method applied to C7:

1. Choose C as the root.
2. Add E, a major third above C.
3. Add G, a perfect fifth above C.
4. Add B♭, a minor seventh above C.

The result is C–E–G–B♭.

What Notes Are in Every Dominant Seventh Chord?

Every dominant seventh chord contains a root, major third, perfect fifth, and minor seventh. The following table applies that formula to all 12 chromatic roots using practical spellings.

Chord	Notes	Chord	Notes
C7	C–E–G–B♭	F♯7	F♯–A♯–C♯–E
D♭7	D♭–F–A♭–C♭	G7	G–B–D–F
D7	D–F♯–A–C	A♭7	A♭–C–E♭–G♭
E♭7	E♭–G–B♭–D♭	A7	A–C♯–E–G
E7	E–G♯–B–D	B♭7	B♭–D–F–A♭
F7	F–A–C–E♭	B7	B–D♯–F♯–A

D♭7 includes C♭ rather than B because C is the seventh letter above D. The two notes sound the same in equal temperament, but C♭ shows the chord’s structure correctly. On guitar or piano, inversions can rearrange these notes without changing the chord’s identity; first-inversion chords place the third in the bass.

Why Is It Called a Dominant Seventh?

The name comes from the dominant, or fifth scale degree, of a key. In C major, the fifth degree is G; stacking diatonic thirds on G produces G–B–D–F, so G7 is the dominant seventh chord, written V7, and it commonly resolves to the tonic C chord.

“Dominant seventh” can also describe chord quality independently of function. C7 always has dominant-seventh quality because its formula is 1–3–5–♭7, but it functions as V7 only when F is the tonal destination. In C major, C7 may instead lead to F as a secondary dominant or appear without a classical dominant function in blues. A closer look at secondary dominant chords explains how a dominant-quality chord can briefly point toward a chord outside the home key.

Why Does a Dominant Seventh Resolve So Strongly?

A dominant seventh chord resolves strongly because its third and seventh form a tritone, an unstable interval spanning six semitones. In G7, B and F form that tritone. When G7 moves to C major, B typically rises by a semitone to C while F falls by a semitone to E.

That contrary motion changes the tense tritone B–F into the stable major third C–E. The root G also moves naturally to C, while D may move to C or E or remain as G7’s fifth before resolving. This voice leading—not merely the chord label—creates the familiar pull of V7–I.

The resolution is conventional rather than compulsory. Composers can delay it, redirect it through a deceptive cadence, substitute another chord, or use dominant sevenths as stable colors. Blues often treats I7, IV7, and V7 as characteristic sonorities instead of making every dominant-quality chord behave like a classical V7.

How Is a Dominant 7th Different From Major 7 and Minor 7?

Dominant 7, major 7, and minor 7 chords differ in the quality of the third or seventh. A dominant seventh has a major third and minor seventh; a major seventh has a major third and major seventh; a minor seventh has a minor third and minor seventh.

Quality	Formula	C-root example	Notes	Typical character
Dominant 7	1–3–5–♭7	C7	C–E–G–B♭	Tense, bluesy
Major 7	1–3–5–7	Cmaj7	C–E–G–B	Smooth, open
Minor 7	1–♭3–5–♭7	Cm7	C–E♭–G–B♭	Darker, mellow

Changing only B♭ to B turns C7 into Cmaj7. Changing E to E♭ turns C7 into Cm7. The major seventh formula and minor seventh construction provide fuller comparisons and additional examples.

Where Are Dominant Seventh Chords Used?

Dominant seventh chords appear wherever musicians want tonal direction, blues color, or harmonic tension. In major-key harmony, the diatonic V7 is the most direct example. The seventh can strengthen a cadence because its tendency tones lead efficiently into the tonic.

Jazz frequently uses dominant sevenths in ii–V–I progressions and adds extensions or alterations such as 9, ♭9, ♯9, 13, or ♭13. Rock, funk, country, and R&B use the chord both functionally and as a repeating groove. Blues commonly makes the I, IV, and V chords all dominant sevenths—for example, C7, F7, and G7 in a C blues—even though only G7 is the key’s conventional V7.

When improvising over an unaltered dominant seventh, the Mixolydian mode is a common starting point because its formula, 1–2–3–4–5–6–♭7, contains all four chord tones. The surrounding progression still determines the best note choices, so a scale should support the chord’s function rather than replace attention to chord tones.

FAQ

Is a dominant 7th chord the same as a major 7th chord?

No. A dominant seventh uses 1–3–5–♭7, while a major seventh uses 1–3–5–7. C7 contains B♭; Cmaj7 contains B natural.

Why is the seventh flattened in a dominant 7th chord?

The lowered seventh places the note 10 semitones above the root, creating a minor seventh interval. In a diatonic V7 chord, that note also helps form the tritone that drives resolution toward the tonic.

Does a dominant 7th chord always have to resolve?

No. V7 commonly resolves to I in functional harmony, but dominant seventh chords may resolve deceptively, move through a sequence, or act as comparatively stable colors in blues and other styles.

What scale works over a dominant 7th chord?

Mixolydian is a common choice over a basic dominant seventh because it contains 1, 3, 5, and ♭7. Altered dominants may call for other scales, and the key, melody, and destination chord should guide the final choice.

Can a dominant 7th chord be built on any root?

Yes. Apply 1–3–5–♭7, or 0–4–7–10 semitones, to any root. Whether the resulting chord functions as the dominant depends on its relationship to the surrounding key.