Piano Intervals – Every Distance, Named

Measuring an interval: count the semitones

On a piano every key is one semitone from its neighbour, black or white. To measure the interval between two notes, count the keys in between, including the second note. From C up to E you pass C♯, D and D♯ before landing on E — four semitones, which is a major third.

Two rules cover almost all interval work. The number (third, fifth, octave) tells you how many letter names you cross; the quality (major, minor, perfect) tells you the exact number of semitones. A third that is four semitones is major, three semitones is minor.

The 12 intervals from any starting note

This table uses C as the starting note. The mapping holds from any root — that is what makes intervals worth learning instead of memorising note pairs.

Perfect, major and minor — why the names differ

Fourths and fifths are called perfect because they sound identical whether you flip them upside down. Play C then G (a fifth) and you hear the same relationship as G then C (a fourth down). Thirds and sixths change character when inverted, so they take major and minor labels instead.

Seconds and sevenths are the tense ones; thirds, sixths and their neighbours are the consonant ones. That is the whole vocabulary you need to describe why a chord sounds calm or restless.

Using intervals on the keyboard

The two shapes that matter most for beginners are the major third and the perfect fifth, because together they build a major triad: C, then four semitones up, then three more. Practise playing C then E, then C then G, until each distance feels automatic under the hand.

Once a fifth feels natural, every power chord, bass note and scale degree becomes predictable. You stop reading individual notes and start reading distances, which is exactly how experienced players sight-read.