Intervals on the guitar

An interval is the distance between two notes. It is measured in half steps: on the guitar, one fret is a half step and two frets are a whole step. With intervals you understand why a chord sounds happy, sad or tense, and you stop learning shapes by heart.

What is an interval?

To measure an interval, count the half steps from the lower note up to the higher one. From E to F there is one half step (one fret). From C to D there are two half steps, that is, a whole step, because C# is in between. The more half steps, the farther apart the two notes are.

Each distance has a name (second, third, fourth...) and an abbreviation whose letter tells you its kind: “m” is minor, “M” is major and “P” is perfect. Half way through the octave there is a special interval, the tritone, of 6 half steps. The octave (12 half steps) is the same note, but higher. If the two notes are the same, it is a unison (0 half steps).

The 12 intervals

These are the twelve intervals, with an example that starts on C.

Why intervals matter

A chord is a group of notes, and its sound depends on the intervals between those notes and its lowest note, the root.

The third decides whether the chord is major or minor. With a major third (M3, 4 half steps) the chord sounds major, like C major; with a minor third (m3, 3 half steps) it sounds minor, like C minor.

The perfect fifth (P5, 7 half steps) gives it stability: almost every chord has one. And the minor seventh (m7, 10 half steps), added to a major chord, turns it into a seventh chord, like C7, which sounds more tense.

Shapes on the fretboard

The guitar has an advantage: the same interval makes the same shape almost everywhere on the fretboard. If you learn what a major third looks like, you recognize it anywhere; only its position changes.

Between two neighboring strings there are 5 half steps. So, when an interval is split between two strings, the higher-pitched note sits 5 frets to the left of where it would be on the same string. For example, a major third is 4 frets on a single string; split between two strings, it becomes 4 − 5 = −1, that is, 1 fret to the left of the root. The exception is the step from the 3rd to the 2nd string (G and B), where there are only 4 half steps: there the count is 4 − 4 = 0, and the note sits on the same fret as the root. Look at the same major third, C–E, in both cases.

A note about names

An interval is named by counting letters, not only half steps. From C to E there are three letters (C, D, E): it is a third. C–Fb sounds the same as C–E (4 half steps), but it is written differently and has a different name: it is a diminished fourth, because it goes from C to F. For now it is enough to know it exists; here we use the most common names.

Hearing the intervals

In all three tools, the “Listen” button plays the two notes: first one and then the other, and then both together. It only appears if your browser can play sound.

Measure an interval

Tap two positions on the fretboard. You will see the name of the interval, the half steps and the two notes, with the lower one marked as the root. Any pair of positions works, even on different strings.

Interval shapes

Tap a note to choose it as the root and pick an interval. The positions of the other note near the root are highlighted, on its string and the neighboring ones. Try a root on the 4th or 3rd string and notice how the shape changes when it moves to the 2nd.

Practice

Two positions are marked at random and you have to say which interval is between them. “Basic” uses the most common ones (m3, M3, P4, P5 and P8); “All” uses all twelve. Each correct answer adds to your streak; a miss resets it.