You'll gain the most from this article if you have a basic knowledge of scales and major and minor chords. 

7th chords are an essential part of expanding your harmonic range on the piano. They shape the mood and texture of piano music across almost all genres, from Baroque-era classical to modern-day pop.

In this article, we introduce the seventh note and explain how it is used to build the three most common 7th chords: "major 7th chords," "minor 7th chords," and "dominant 7th chords." We will explore how each of the different chords sound, how you can use them, and some famous examples of each 7th chord in action.

Note: To be as clear as possible, we'll use "seventh" to refer to the seventh note in a scale and "7th chord" to refer to the types of chord.

What's a seventh note?

There are seven notes in any scale, named for their position relative to the root note. We're interested in the seventh. Since this is different for major or minor scales, there are two types of seventh note:

Major seventh note

The major seventh note is always eleven semitones above the root note. Here's an easier way to remember it: one octave up, one semitone down.

Minor seventh note

The minor seventh note is always ten semitones above the root note. Here's an easier way to remember it: one octave up, two semitones down.

What's a 7th chord?

A 7th chord takes a major or minor triad and adds either a major or minor seventh (in most cases). Here, we will focus on the three most common 7th chords:

• Major 7th chord – A major triad with a major seventh
• Minor 7th chord – A minor triad with a minor seventh
• Dominant 7th chord – A major triad with a minor seventh

Major and minor triads are the most basic chords at your fingertips, evoking simple "happy" or "sad" emotions when played on their own. The fourth note in a 7th chord adds an extra layer of harmony, which brings a different flavor to the basic triad.

Also, 7th chords are an excellent way to lead the listener to the next chord. They hint at where you are taking them and make the chord that follows feel more natural—for example, the C7 chord leads very well to an F major chord.

Below we'll dive deeper into each type of 7th chord.

Major 7th chords

A major 7th chord is a triad with a major seventh note added.

To play a major 7th chord on the piano, start with the major triad, but instead of using your first, third, and fifth fingers, place your first, second, and third fingers on the root, third, and fifth notes, respectively. This might be a little uncomfortable at first if you have small hands, but your hands will be able to cover a wider range comfortably over time with practice.

Now, place your fifth finger on the major seventh note, which is four keys up from your third finger (four semitones above the fifth note). If your hands are larger, you may prefer to use your fourth finger for this. Go with whatever is more comfortable. It should look—and sound—like this:

The purely "happy" or "light" sound of a major chord is suddenly so much richer and more evocative when it's transformed into a major 7th chord. It adds an emotional element, which is why Romantic-era piano pieces, jazz music, and modern piano ballads use a lot of major 7th chords.

In sheet music, you might see the major 7th chord written in one of these ways: maj7, M7, Δ, ⑦. The most common form is maj7, where any alterations, added tones, or omissions are sometimes also superscripted, such as Cmaj⁷.

Minor 7th chords

A minor 7th chord is a triad with a minor seventh note added.

To play a major 7th chord on the piano, start with the minor triad and—like with a major 7th chord—place your first, second, and third fingers on the root, third, and fifth notes.

Now, place your fifth finger on the minor seventh, which is three keys up from your third finger (three semitones above the fifth note). If your hands are larger, you may prefer to use your fourth finger. Again, go with whatever is more comfortable. It should look—and sound—like this:

Similarly to the major 7th chord, adding the seventh note introduces richness, this time softening the "sad" sound of a minor chord to make it more reflective than dark. Again, Romantic-era pieces, jazz music, and modern piano ballads all use a lot of minor 7th chords.

In sheet music, you might see the minor 7th chord written in one of three ways: Cm7, Cmin7, or C–7.

Dominant 7th chords

A dominant 7th chord is a major triad with a minor seventh note added.

Historically, this chord is often built on the fifth note of the major scale. For example, in the C major scale, the fifth note is a G. The triad on the 5th note, here G major, is generally called the "dominant" in functional harmony. When we add a 7th to this G major triad based on the C major scale that we're in, we end up with G, B, D and F. As this is a seventh chord on the dominant, it is called dominant 7th chord.

To play a dominant 7th chord on the piano, start with the major triad, placing your first, second, and middle fingers on the root, third, and fifth notes.

Now, place your fifth finger on the minor seventh note. You can use your fourth finger instead if it's more comfortable. It should look—and sound—like this:

The combination of a major third with a minor seventh gives dominant 7th chords an inbuilt dissonance, which can make them more impactful than other 7th chords. Also, because we naturally wait for the dissonance to resolve, dominant 7th chords are a great way to add a sense of movement to music.

In sheet music, dominant chords are based on the fifth degree of a scale, so we write them with the Roman numeral V. This means dominant 7th chords would be noted with V7.

The other 7th chords

You may be thinking "there's one missing." So far, here's what we've covered:

• Major chord with a major 7th (major 7th chord)
• Minor chord with a minor 7th (minor 7th chord)
• Major chord with a minor 7th (7th chord)

So what about a minor chord with a major 7th? Well, it exists!

It's called the "minor major 7th chord" and it's known for being very dissonant and spooky. In fact, Bernard Herrmann used it so much in his score for Alfred Hitchcock's classic horror movie Psycho that it's also known as "The Hitchcock Chord." 

Besides the minor major 7th chord, there are also less-common 7th chords based on augmented or diminished triads. Outside of film scores and jazz pieces, you're unlikely to hear them much, so consider this an honorable mention for now.

Which songs use 7th chords?

Very few songs will only use basic triads, so 7th chords are easy to find in almost every genre of piano music. Here are some examples to give you an idea of how they sound within famous songs and compositions:

Songs using a Major 7th chord

Erik Satie – "Gymnopédie No. 1"
This gentle masterpiece perfectly illustrates how a major 7th chord can create a dreamy, nostalgic feeling—plus, the following chord is also a major 7th, making it doubly magical.

Billie Eilish – "Everything I Wanted"

A major 7th chord starts the main progression of this delicate, evocative ballad, then returns throughout every section. It's a great example of how the chord can make even minimalist songs sound richer.

Songs using a Minor 7th chord

Coldplay – "The Scientist"

The minor 7th chord at the start of the chorus progression brings some hope and light to what might have felt simply sad with a minor triad.

Norah Jones – "Don't Know Why"

A lot of jazz and blues influence seeps into this smooth, nostalgic ballad. Most of this lies in the bluesy progression and embellishments, but a minor 7th chord leads into the titular lyrics.

Songs using a dominant 7th chord

Johann Sebastian Bach – "Prelude No. 1 in C"

This flowing work of art features a dominant 7th chord as the third in the progression. It sounds almost playful and resolves back to the first chord oh-so-sweetly.

The Beatles – "Hey Jude"

The Fab Four started out playing rock 'n' roll, so it's no surprise they knew how to use 7th chords to create interesting harmonies and lead the listener. You can hear a dominant 7th chord as the third chord in each verse, then again at the start of each chorus.