What an energy curve is
An energy curve is your set drawn as a line: one point per track, in playing order, height being how hard that track hits. It is the shape of the night as a picture rather than as a feeling, and it is the fastest way to see something about a set that a tracklist hides completely — that the thing you planned as a slow build actually peaks at track four and spends the next hour trying to get back.
DJs have always read this by ear, which works and is slow: you find out how a set flows by playing it, and the room you find out in is the one that paid to be there. Drawing it first does not replace the ear. It catches the things the ear would have caught on the night, on a Tuesday instead.
How to read the chart
The solid line is your set, left to right in playing order. The faint line behind it is the shape a set of that kind usually wants — not a rule, a reference. Where the two run together the set is doing what it set out to do; where they pull apart is where the interesting question is, and sometimes the answer is that the reference is wrong for what you are playing.
Three things are worth looking for. A step that goes nearly vertical between two adjacent tracks — the room feels that as a lurch, up or down. A long flat stretch in the middle, which is not calm but stalled. And a peak that arrives too early, which is the most common problem in a set someone built by picking their favourite tracks and then ordering them.
Points drawn hollow are ones where we had no energy to read and estimated from position instead. A curve made mostly of hollow points still shows you the shape you built, but the numbers under it are ours, not your music's.
The shapes sets usually take
A warm-up is a ramp that never arrives. It ends higher than it started and lower than where the next DJ needs to begin, and the discipline of it is refusing the peak you are perfectly capable of playing. A warm-up that peaks is the single most reliable way to make a headliner's job harder, and it shows up on the chart instantly: a bump in the middle where the line should still be climbing.
A peak-time set climbs, holds high with dips for air, and lands. The dips matter: an hour at nine is not a peak, it is a plateau, and a room stops hearing intensity that never lets up. The chart makes this obvious — a good peak-time curve looks like a mountain range near the top, not a table.
A journey set is the one that earns the long slots: it moves through more than one arc, with real valleys, and treats an hour as something with chapters. A closing set does the opposite of a warm-up — it starts where the last DJ left the room and walks it down, and its ending is the part people remember. Each of these wants a different reference line, which is why the tool asks what kind of set this is before it measures anything.
Energy is not BPM
This is the confusion worth undoing. Tempo is one input to how hard a track hits, and it is not the biggest one. A sparse 140 BPM roller can sit under a dense 124 BPM house track all night; a dub techno cut at 130 can be the quietest thing in an hour. Sets ordered by BPM alone read as mechanical for exactly this reason — the numbers climb and the room does not.
When a track carries an energy rating in its tags — Mixed In Key writes one, and plenty of DJs type their own — that number is used directly, because someone who listened to it decided it. When there is no rating, BPM is used as an estimate, anchored to the genre so that 128 does not mean the same thing in deep house and in hard techno. The distinction is kept visible rather than smoothed over, because a curve built from estimates and a curve built from ratings deserve different amounts of trust.
What this tool checks
Three readings, and it says how many of each it found. Energy jumps: steps between adjacent tracks bigger than the genre normally takes, in either direction. Harmonic clashes: pairs whose keys fight, counted only where both tracks actually have a key — an unknown key is not a clash, and warning about half a library with no tags is how a tool teaches you to ignore it. Misplaced peaks: the loudest moment landing somewhere the shape does not want it.
The score from 1 to 10 blends three things: how closely the curve follows the shape, how clean the transitions are, and how the set lands. It is a summary, not a verdict — a 6 with one huge jump in it is a different set from a 6 that is slightly flat throughout, and the counts above tell you which one you have.