C7 piano chord, C dominant 7th notes and fingering.

The C7 piano chord is C dominant 7th: C, E, G and Bb. It is the C major triad (C, E, G) with a minor seventh (Bb) added on top, ten semitones above the root. A plain 7 in a chord name, as in C7, always means this flat seventh, not the major seventh.

How to play C7 on piano

1. Find C on the keyboard. C is the white key just left of the pair of black keys.
2. With your right hand, put finger 1 on C, finger 2 on E, finger 3 on G and finger 5 on Bb. Finger 1 is the thumb.
3. Press all four keys together. In root position they run from C4 to Bb4, a reach of 10 semitones. Play chord sounds them together and Arpeggio sounds them one by one, from the bottom up.
4. Click Left hand to see the left hand. It plays C3 to Bb3, one octave lower: C with finger 5, E with finger 3, G with finger 2, Bb with finger 1.
5. The cards under the keyboard hold the four positions, with C, E, G and Bb at the bottom in turn. Play and Arpeggio on a card play that position.
6. Open Note names. As written the keys read C, E, G and Bb. Sharps shows C, E, G and A#, and Flats shows C, E, G and Bb. This chord is written with flats, so As written and Flats match.

How C7 is built

Counted from the root, the formula is 0, 4, 7, 10. Stacked on each other the gaps are 4 + 3 + 3: a major third, a minor third and another minor third. The third (E) and the seventh (Bb) are 6 semitones apart, which is a tritone, the most tense interval in the chord. That pair is what makes the chord lean toward a resolution.

Worked example: the pitch of C4. On a piano tuned to A4 = 440 Hz, a note 9 semitones below A4 has the frequency 440 × 2^(-9/12), which is about 261.63 Hz. E4 is 5 semitones below A4, so 440 × 2^(-5/12) gives about 329.63 Hz.

What the keys look like under your hand

The black key nearest C is C# on its right. On its left there is none, because B and C are only a semitone apart. One of the four notes is a black key (Bb) and three are white keys (C, E and G). Your little finger plays Bb, a black key with A and B beside it. The little finger is short, so let the hand lean a little toward its edge and aim for the middle of the key.

C7 inversions and fingering

C7 has four positions. In root position C is at the bottom. In the first inversion, E is at the bottom and the chord is written C7/E. In the second inversion, G is at the bottom and the chord is written C7/G. In the third inversion, Bb is at the bottom and the chord is written C7/Bb. The tightest reach, 8 semitones from the lowest key to the highest, is the first inversion. The widest, at 10, is the root position.

The keys that hold C7

C7 fits two of the major and natural minor keys that have a standard key signature, which means every note of it comes from that key's scale. The simplest is F major, with 1 flat, where it is chord V7.

Progressions that use C7, with the chord numbers and the chords in that key:

• F major: Imaj7-IVmaj7-V7-Imaj7, which is Fmaj7, Bbmaj7, C7, Fmaj7, the three-chord cadence of folk, rock and blues.
• D minor: i7-VII7-VImaj7-VII7, which is Dm7, C7, Bbmaj7, C7, a rocking figure between VII and VI.
• F major: vi7-IVmaj7-Imaj7-V7, which is Dm7, Bbmaj7, Fmaj7, C7, the four-chord loop started from the vi chord.

Blues: a 12-bar blues in C is built on C7, F7 and G7.

Here is a worked example in F major. The chord before C7 in the first progression above is Bbmaj7 (Bb, D, F and A). From Bbmaj7 in root position, the closest way to reach C7 is its third inversion (Bb, C, E and G, lowest note first): one note stays where it is, and the others move 5 semitones in total, counting each note against the note in the same place from the bottom.

Look at the top three notes of C7: E, G and Bb make a E diminished chord (E, G and Bb). A dominant 7th is a diminished triad with the root added underneath.

What C7 sounds like

The dominant 7th is restless. Its tritone between E and Bb pulls toward a resolution, and the chord most naturally moves to F, a fifth below C. It is the sound of the blues too, where every chord can be a dominant 7th.

Here C7 is the V7 chord in F major and the VII7 chord in D minor. In a 12-bar blues in C the three chords are C7, F7 and G7. In minor keys the same chord appears as V7 of F minor, using the raised seventh of the harmonic minor scale.

A common mistake with C7

A common mistake is pressing B instead of Bb on top, one semitone higher than the seventh of C7. That gives Cmaj7 (C, E, G and B), which sounds soft where C7 sounds restless. Check the top note: it should be the lower of the two keys.

Chords to learn next

Chords close to C7: C major (the same chord without the seventh; shares C, E and G); Cmaj7 (a major seventh instead; shares C, E and G); Cm7 (a minor third instead; shares C, G and Bb); F major (the chord it leads to; shares C).

Once C7 feels easy, play it and then F major to hear the chord resolve. For chords beyond these six types, and for guitar and ukulele shapes, use the chord finder. To play along with your computer keys, open the virtual piano. The piano chords page lists all 72 chords.