Prop betting terms, explained
Each page opens with a one-sentence definition, works one example through with the arithmetic, and answers the common questions. It is education about odds and data, not advice.
Updated
- Player prop lineA player prop line is the number a sportsbook posts for one player's stat in one game, such as 24.5 points, with a price on the over and a price on the under.Read the explanation →
- No-vig oddsNo-vig odds, also called fair odds, are a two-sided price with the sportsbook's margin (the vig, or juice) taken out, so the two sides' chances add up to 100%.Read the explanation →
- Implied probabilityImplied probability is the chance a price says an outcome has, found by converting the odds, and it puts American, decimal and fractional prices on one 0 to 100% scale.Read the explanation →
- Hit rateA hit rate is the share of a player's games that finished on one side of a prop line, and over a small sample it is a wide range rather than a single number, which a Wilson interval makes visible.Read the explanation →
- Line movementLine movement is the change in a prop's posted number or price between when a sportsbook first posts it and now, and on Probetrics "moved" compares today's consensus number with the first one we stored.Read the explanation →
- MiddleA middle is a gap between two sportsbooks' numbers on the same prop, such as one book's over 24.5 and another's under 26.5, where a result inside the gap wins both sides.Read the explanation →
- Alternate lineAn alternate line is a different number for the same prop than the main line, priced to match: an easier number pays less, a harder number pays more.Read the explanation →
- CalibrationCalibration is whether stated probabilities match what happens: of the picks a model gave about 70%, about 70% should win.Read the explanation →
- Walk-forward backtestingWalk-forward backtesting scores a model on games it has not seen by pricing each game only from what was known before it, moving forward through time.Read the explanation →
- Market-anchored probabilityA market-anchored probability starts from the sportsbook's no-vig price for a game and lets a model change it only where testing has shown the model adds information.Read the explanation →
Odds calculator →Every props board →Read a prop in two minutes →How the models are tested →
These pages explain arithmetic and vocabulary. They do not recommend a bet, a side, an amount or a sportsbook. For information only, not betting advice. 21+ only. Gambling problem? Call or text 1-800-GAMBLER.