Intervals Explained
Intervals are the atoms of music — the distances between notes. Chords, scales and melodies are all just intervals stacked in different ways, so understanding them makes everything else fall into place.
Semitones and tones
The smallest move in music is a semitone (half-step): one fret on guitar, or one key to the very next key on piano. Two semitones stacked make a whole tone. Every larger interval is just a count of semitones — which means intervals are really a kind of musical measuring tape.
The interval names
From a starting note, the common intervals within an octave are: minor and major 2nd (1–2 semitones), minor and major 3rd (3–4), perfect 4th (5), the tritone (6), perfect 5th (7), minor and major 6th (8–9), minor and major 7th (10–11), and the octave (12). The 3rd tells you major vs. minor; the 5th gives a chord its stability.
Consonance and tension
Your ear hears pitch as a ratio. Simple ratios sound consonant: the octave is 2:1, the perfect fifth is almost exactly 3:2 — smooth and restful. Complex ratios sound dissonant: the tritone clashes and feels unstable, which is exactly why it's used to create tension that pulls toward resolution.
Why the fifth rules
After the octave, the perfect fifthis the most consonant interval there is — it's literally the strongest overtone a vibrating string produces. That's why the whole circle of fifths is built on it, and why moving chords by a fifth feels so natural.
Intervals are best learned by ear as well as by sight. Open the tool to see any interval on the neck and hear it, then head to ear training to learn to recognise them by sound.
Reading only gets you so far — open the interactive fretboard and watch these ideas light up on guitar and piano.
Enter the toolFrequently asked
What is an interval in music?
An interval is the distance in pitch between two notes, measured in semitones (half-steps). Every scale, chord and melody is built from intervals.
What is the smallest interval?
On a standard instrument, the semitone (half-step) — one fret on guitar, or one key to the very next key on piano. Two semitones make a whole tone.
Why do some intervals sound tense?
Consonant intervals like the octave and perfect fifth have simple frequency ratios, so they blend. Dissonant ones like the tritone have complex ratios and clash, creating tension that wants to resolve.