What notes are in a C7 chord?

C7 contains four notes: C (root), E (major third), G (perfect fifth), and B♭ (minor seventh — the "blue note").

How is C7 different from Cmaj7?

Only the seventh changes. C7 has B♭ (minor 7th); Cmaj7 has B natural (major 7th). C7 sounds bluesy and wants to resolve to F; Cmaj7 sounds stable and serves as a tonic.

What does the "7" symbol mean by itself?

By convention, "C7" means dominant 7th — major triad plus a minor 7th. Major 7th chords are always written "Cmaj7" or "CΔ7" to distinguish them.

Where does C7 appear in famous music?

Every blues song in C uses C7 as the I, F7 as the IV, G7 as the V. Beethoven's Symphony No. 1 famously opens with a deceptive C7 chord (resolving to F major before the C-major home key is even established).

C dominant 7 chord — notes, intervals, and practice

C dominant 7 (C7) — C, E, G, B♭ — is C major with a minor 7th on top. The chord is the V7 of F major, the V7 of F minor, and the I7 of any blues in C. The defining sound of the blues — every 12-bar blues in C is built on C7, F7, and G7.

Intervals

The C dominant 7 chord stacks two thirds on the root. Each interval and its size in semitones:

C→Emajor 3rd4 semitones
E→Gminor 3rd3 semitones
G→Bbminor 3rd3 semitones

On the keyboard

Each note of the C dominant 7 chord highlighted on a piano. Pitch class is what matters — any octave works.

On the guitar

One voicing of the C dominant 7 chord on a six-string guitar fretboard.

1C
3E
5G
♭7Bb

Common mistakes

C7 has B♭ as its 7th — a half-step lower than Cmaj7 (which has B natural). The B♭ is the chord's "blue note" — it's what gives C7 its bluesy, resolution-seeking sound. The most common error is writing Cmaj7 when C7 is meant, or vice versa. On guitar, the open C7 voicing (x32310) is the standard.

In context

C7 is the V7 of F major (C7 → F is the cadence in F-major blues), the V7 of F minor, and the I7 of C blues. In the 12-bar blues, C7 sits as the I, F7 as the IV, and G7 as the V. The chord is also the centerpiece of every jazz cadence resolving to F.

Drill it

The C dominant 7 chord is one of 48 in the Chord Trainer. Open the full trainer to practice it alongside related chords with timing and best-time tracking.

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Frequently asked

What notes are in a C7 chord?: C7 contains four notes: C (root), E (major third), G (perfect fifth), and B♭ (minor seventh — the "blue note").
How is C7 different from Cmaj7?: Only the seventh changes. C7 has B♭ (minor 7th); Cmaj7 has B natural (major 7th). C7 sounds bluesy and wants to resolve to F; Cmaj7 sounds stable and serves as a tonic.
What does the "7" symbol mean by itself?: By convention, "C7" means dominant 7th — major triad plus a minor 7th. Major 7th chords are always written "Cmaj7" or "CΔ7" to distinguish them.
Where does C7 appear in famous music?: Every blues song in C uses C7 as the I, F7 as the IV, G7 as the V. Beethoven's Symphony No. 1 famously opens with a deceptive C7 chord (resolving to F major before the C-major home key is even established).