The neighborhood.
Every key is a neighborhood of chords. Some are close — connected by smooth voice leading, sharing common tones. Others are distant — chromatic leaps with no shared notes. This map shows the harmonic terrain. Click any chord. See where it connects.
Inner ring: the seven diatonic chords of the key. Outer ring: common borrowed and secondary dominants. Solid borders are diatonic; dashed borders are borrowed. Colors follow the Hooktheory degree system.
Lines between chords show voice leading distance — how many total semitones all voices move. Thicker, brighter lines mean smoother connections. Green is very smooth. Violet is smooth. Amber is moderate. Gray is a wide leap.
Click two chords to compare their direct connection and see the smoothest paths through intermediary chords. Sometimes going through a pivot chord creates a smoother journey than jumping directly.
The tonic (I) and submediant (vi) are the closest chords in the field. They share two common tones and only one voice moves by two semitones. This is why the vi chord feels like home — it almost is home.
The dominant (V) connects to nearly everything with moderate distance. It is the hub of the harmonic network. This is why V is the most versatile chord for progression building — it can reach anywhere.
Borrowed chords from the parallel minor (iv, bVI, bVII) create routes that the diatonic field alone cannot offer. The bVI-to-I connection has zero common tones — its beauty comes from voice leading smoothness despite harmonic distance.
Switching between triads and seventh chords changes the entire topology. Seventh chords have four voices instead of three, creating more common tones between neighbors but also more total motion. The field gets denser and more interconnected.
The smoothest possible path between two chords is not always the direct one. Sometimes routing through a pivot chord — like using ii between IV and V — creates a more natural harmonic flow than the direct jump.