Music Intervals Explained
A musical interval is the distance between two notes, counted in half steps: C up to E is four half steps, a major third. Intervals are the atoms of music. Every melody is a string of intervals and every chord is a stack of them, so learning to see and hear intervals is the quickest way to understand how the rest of harmony is put together.
Learn intervals by playing them
Hear an interval or chord, play it back, know instantly if you nailed it. No download, no signup. MIDI keyboard or microphone.
▶ Try ChordRunner Free Free in the browser - intervals are how every chord is built.What an interval is
Count the half steps between two notes and you have named their interval. One half step is a minor second, two is a major second, and so on up to twelve, the octave. Each interval has its own colour: some sound sweet and stable (the third, the fifth, the octave), some sound tense and restless (the minor second, the tritone). Musicians hear those colours instantly, and that skill is learnable by anyone through practice.
Explore every interval from C
Pick an interval. The blue key is C, the orange key is the second note.
Every interval and its sound
The quickest way to learn intervals is to peg each one to a song you know. The perfect fifth opens Twinkle Twinkle and the Star Wars theme; the major third is bright and bugle-like; the minor third is the sound of Greensleeves; the tritone, six half steps and dead centre, is the tense Simpsons leap. Once a reference tune is glued to each interval, you can name what you hear in real time, which is the foundation of playing by ear.
From intervals to chords
Chords are just intervals stacked, almost always in thirds. A major triad is a major third with a minor third on top; flip those and you get a minor triad. Add another third for a seventh chord, and keep going for extensions. This is why interval fluency pays off everywhere: see the intervals and you see the chord. It also underpins chord recognition, since telling a major third from a minor third by ear is what tells a major chord from a minor one.
Practise intervals in the game
Reading about intervals only gets you so far; you have to hear them. In ChordRunner's Ear Training you hear an interval or chord and play it back on your instrument, getting told immediately whether you matched it. That hear-it-then-play-it loop builds the ear-to-hand connection that turns interval knowledge into real musicianship. Play on a MIDI keyboard or through your microphone, free in the browser.
Common questions
What is a musical interval?
An interval is the distance in pitch between two notes, measured in half steps. From C to the E above it is four half steps, a major third. Intervals are the building blocks of everything: melodies are intervals in a line, chords are intervals stacked together.
How many intervals are there in an octave?
Within one octave there are twelve half steps, giving thirteen intervals counting the unison and the octave itself: minor and major seconds, minor and major thirds, perfect fourth, tritone, perfect fifth, minor and major sixths, minor and major sevenths, and the octave.
How do intervals build chords?
Chords are stacked intervals, usually thirds. A major triad is a major third plus a minor third from the root; a minor triad flips them. A seventh chord adds another third on top. So learning to see and hear intervals is the fastest route to understanding chords.
How do I practise recognising intervals?
By hearing them and playing them back, not by memorising a chart. In ChordRunner's Ear Training you hear intervals and chords and reproduce them on your instrument, on a MIDI keyboard or through your microphone, which trains real recall rather than passive recognition.