Minor Third

A C minor chord contains C, E flat and G. C is the root and G is the fifth. E flat is the third above the root, and its distance from C is a minor third.

Move E flat up one semitone to E and the chord becomes C major. The root and fifth stay where they are. This makes the third the clearest note to compare when you want to hear the difference between major and minor harmony.

You may describe C minor as darker or more closed than C major. Those words can help you remember the contrast, but the musical change is exact: E becomes E flat. Play C and G first, then add E flat and replace it with E. Hearing the same frame around both thirds makes the difference easier to recognize.

The number and the quality measure different parts of the interval.

Count the letter names from C to E flat, including both ends: C, D, E. That makes it a third. Then count the semitones. There are three, which makes it minor.

C to E also spans three letter names, so it is another kind of third. It covers four semitones and is therefore a major third. If you need the full counting method, start with What Is an Interval?.

The spelling matters. C to E flat is a minor third because it spans three letter names. C to D sharp uses the same piano keys in equal temperament, but it spans only C and D, so it is an augmented second. The sound may match on a piano while the written function differs.

No. A chord is called minor when there is a minor third above its root. A minor third can also appear between two other chord tones.

C major contains C, E and G. E to G is a minor third, but C to E is a major third, so the chord is C major. C minor reverses the order: C to E flat is a minor third and E flat to G is a major third.

This is why you should first find the root when identifying a chord. Measure the third from that note. The other intervals still shape the chord, but they do not determine its basic major or minor name.

Several common chord families begin with a minor third:

Other chords contain a minor third somewhere else. In C major, E to G is a minor third. In a dominant seventh chord such as G7, B to D is one too. The interval is common; its position relative to the root determines what it tells you about the chord.

Natural minor, dorian and phrygian all place a minor third above their root. So do the minor pentatonic and blues scales.

That shared third puts them on the minor side of the family, but the remaining notes make them different. Dorian has a major sixth, natural minor has a minor sixth and phrygian also lowers the second. The third gives you a useful first answer; the other scale degrees finish the identification.

The harmonic and melodic minor scales also keep the minor third. Raising other notes changes how their melodies and chords behave without removing the basic minor relationship from root to third.

A pure minor third has a frequency ratio of 6:5 and measures about 316 cents. Its vibration patterns meet regularly, which can make sustained notes blend with relatively little beating.

A modern piano uses equal temperament. Three equal semitones make a minor third of 300 cents, about sixteen cents narrower than the pure 6:5 version. The piano uses that fixed compromise so every key remains usable without retuning.

Singers and string players can adjust pitch while a note is sounding. In a sustained chord, they may place a minor third slightly wider when that gives the ensemble a cleaner blend. This is a tuning difference, not a different interval name. Read more in Tuning and Temperament.