An edge is the gap between our number and the book's number. Same words, same math, every page - here is how to read it, and how to pick the prop worth playing.
Every price a book posts is a probability in disguise. A -110 line says "this lands about 52% of the time." Our models put their own number on the same prop. The edge is simply how far apart those two numbers are.
Measured in percentage points. Positive means the price is beatable. Zero or negative means the book has it right - pass, no matter how good the lean feels.
A real example, from an NBA points prop:
The book prices it like a coin flip; the sims land it 61 times in 100. That 9-point gap is the edge - and the fair price for 61% is about -156, so -110 is genuinely cheap. If the price had already moved to -170, the edge would be gone even though the read never changed.
Wherever you see an edge on Propedia, it falls in one of four bands. The words never change meaning between sports:
| Band | Edge | What it means |
|---|---|---|
| STRONG | +10 or more | The book is well off our number. The plays we build around. |
| LEAN | +5 to +9 | A real gap, worth playing at the posted price. |
| SLIGHT | +1 to +4 | A nudge, not a play on its own. Parlay filler at most. |
| NO EDGE | 0 or less | The price already agrees with us. Pass. |
The stars you see next to a prop are different from the edge: they are our conviction in the number itself - how much data sits behind it and how steadily it has graded. A big edge on a thin number is worth less than a solid edge on a proven one.
The ingredients differ by sport - the edge math never does.
10,000-run game simulations on tonight's actual rotations - who is playing, who is out, real minutes. The sim count at the line is our chance.
A model ensemble over player usage, matchup and game script, anchored to the market so a hot streak cannot drag it away from reality.
Scoring-rate models by position and situation, adjusted for the confirmed starting goalie - the single biggest swing in a hockey prop.
Team and player projections graded against the posted line, with starting-QB and injury docks applied before any edge is shown.
A ladder is one prop at every rung the book sells. Each rung has its own price, so each rung has its own edge. Two numbers do the work:
| RUNG (PTS) | PRICE | OUR CHANCE | GAP | EDGE | |
|---|---|---|---|---|---|
| 19.5 | -420 | 84% | +5.8 | +2 | |
| 21.5 | -215 | 74% | +3.8 | +6 | BEST GAP |
| 23.5 | -125 | 66% | +1.8 | +9 | SWEET SPOT |
| 24.5 | -110 | 61% | +0.8 | +9 | |
| 26.5 | +130 | 47% | -1.2 | +3 |
Our projection minus the rung, in the stat itself - points here. His projection is 25.3, so the 21.5 rung carries +3.8 points of cushion. Bigger gap = more room for a bad quarter.
Our chance of clearing that rung minus what the rung's price implies. It is per-rung: the same player can be +9 on one rung and +2 on another.
Five checks, in order. A prop that fails one is not the play, whatever the edge says:
One vocabulary, every surface: if a page ever uses these words to mean something else, that is a bug - tell us in #feedback and we will fix it.