Perfect Fifth Interval

perfect fifth overview

A perfect fifth spans seven half steps. From C, for example, a perfect fifth up is G. The number in its name counts the letter names it covers, including both ends: from C to G, C D E F G is five, so it is a fifth. The seven half steps make it perfect. Fourths and fifths, like unisons and octaves, are called perfect: they have no major or minor form.

Lesson Steps

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The perfect fifth is the most stable interval after the octave. It frames every major and minor chord, from the root to the 5th (C to G in C major and C minor), and on its own it sounds open, neither major nor minor. Because it sounds so complete, a bare fifth in the bass is often enough to establish a key.

On the keyboard, a perfect fifth always has six keys between its two notes. Depending on where it starts, those notes can fall on white or black keys, which gives it four different shapes.

The shapes of the perfect fifth on the piano

Each shape sits a little differently under the hand, so it is worth knowing them all. Under each keyboard, the same notes are on the staff: played together, then up, then down.

White key to white key: C to G

Perfect fifths that share this same shape are C–G, D–A, E–B, F–C, G–D, and A–E. There are six keys in between (three white, three black).

White key to black key: B to F♯

B–F♯ is the only perfect fifth with this shape. There are six keys in between (four white, two black).

Black key to white key: B♭ to F

B♭–F is the only perfect fifth with this shape. There are six keys in between (four white, two black).

Black key to black key: D♭ to A♭

Perfect fifths that share this same shape are D♭–A♭, E♭–B♭, G♭–D♭, and A♭–E♭. There are six keys in between (four white, two black).

Reading the perfect fifth on the staff

A fifth goes from a line to a line with one line in between, or from a space to a space with one space in between. Both notes are on lines, or both are in spaces. That stays true whatever the accidentals are: every fifth looks like a fifth, and the accidentals tell us its quality.

This is what makes intervals so useful for reading. Rather than naming every note from the clef, we read from one note to the next: once we know where we are, the shape on the staff tells us how far to move. Reading this way is relational rather than absolute, and it is much faster.

It works the same in the treble and bass clef, and at any height on the staff, so a reader who knows the look of a fifth recognizes it everywhere.

The perfect fifth in the hand

In a five-finger pattern, a fifth is the full span of the hand, thumb to 5th finger: 1 and 5 in either hand. This is the one interval where the staff, the keyboard and the hand line up most simply; the outer notes of a C position are a fifth apart.

The spacing on the staff and the spacing in the hand belong together. In a five-finger pattern, a step on the staff is often the next finger, and a skipped note a skipped finger, so the distance we see becomes a distance we feel.

Inverting the perfect fifth

If we move the lower note up an octave (or the upper note down one), a perfect fifth becomes a perfect fourth: C to G turns into G to C. The numbers of an interval and its inversion add up to nine, and their half steps to twelve (7 + 5). A perfect interval stays perfect.

On the keyboard the shapes swap as well: a white-to-black shape inverts to a black-to-white one, and a white-to-white shape stays white to white.

Practice the perfect fifth

Play the first shape, C to G, together and then one note after the other, and listen to the sound before moving on.
Find the same shape at every place it occurs on the keyboard (the lists under each image), then the other shapes. Notice how the hand changes as the keys change color, while the sound stays a perfect fifth.
Play a perfect fifth up from all twelve keys, naming the upper note as we go.
Read it: look for perfect fifths in a piece we know, and before playing each one, name the interval from its look on the staff.
Once the shapes are reliable, play the interval without looking at the hands, feeling the span between the fingers.

Avoid common mistakes with the perfect fifth

Assuming every white-key fifth is perfect. Six of the seven are, but B up to F is a tritone. The perfect fifth from B needs F♯.
Counting keys instead of half steps. The starting key isn’t counted: from C, the first half step is C♯.
Reading every note from the clef. Naming each note separately is slow. Reading the interval from the previous note is what lets the eye stay ahead of the hands.