Sports betting glossary

Placing offsetting bets across multiple venues to guarantee profit regardless of outcome. Rare and short-lived in mature markets; modest in size when found.

The discipline of sizing each bet as a small, consistent fraction of your total betting bankroll. Typical sizing: 1-2% per bet. Prevents variance from wiping out a bankroll.

The difference between the price you bet at and the price the market settled at by game time. Positive CLV consistently is the single best predictor of profitable long-term betting.

The average profit (or loss) per bet over infinite repetitions, given the true probability of winning vs the price paid. A bet has +EV when the price is better than the true probability.

The percentage-point difference between a venue's implied probability and a more accurate reference probability. Positive edge means the venue is cheaper than fair — a buy signal.

Bets on outcomes that resolve later in a season — championship winner, division winner, MVP, win total, etc. Vig is usually higher (15-25%) than game lines because the field is wide and the time horizon long.

To bet against a particular side, person, or trend. "Fade the public" = bet against whichever side the majority of bettors are taking.

Placing a second bet on the OPPOSITE side of an existing position to lock in profit or reduce loss. Common at the end of long-running futures bets when you have a live ticket near settlement.

The probability that a given price implies an outcome has of occurring. For American odds, +200 implies 33.3%, -150 implies 60%. Pure math conversion — no model needed.

A formula for optimal bet sizing that maximizes long-run bankroll growth given an edge. Full Kelly is mathematically optimal but emotionally aggressive; most pros use fractional (quarter, half) Kelly.

Kalshi charges a per-contract trading fee of max(1¢, ceil(0.07 × p × (1-p) × 100)), capped at 7¢. Fees are highest near 50¢ (peak ~1.75¢) and lower at extremes.

A bet on which team or contestant wins outright, regardless of margin. Listed as American odds: favorites have negative numbers (-150 means bet $150 to win $100); underdogs positive (+130 means bet $100 to win $130).

A sportsbook price with the vigorish removed, expressed as a clean probability that sums with the other side to exactly 100%. The standard reference for comparing prices across books.

A single bet combining multiple selections that all must win for the parlay to pay out. Pays larger but carries multiplicative vig — typically -EV for the bettor.

A bet on a specific outcome WITHIN a game or season, unrelated to the final score. Player props (LeBron points), team props (first to score), event props (coin toss).

A bet that ends in a tie because the actual result lands exactly on the line. Stake is returned with no win or loss. Most common on whole-point spreads and totals.

A handicap applied to a favored team's final score to balance both sides at approximately 50/50. Lakers -3.5 means Lakers must win by 4+ to cover; Celtics +3.5 wins if Lakers win by 3 or fewer (or lose).

Sharp = sophisticated, model-driven, value-focused bettors who beat the market. Square = casual, narrative-driven bettors. Books treat them differently — sharps get limited; squares get courted.

A bet on whether the combined score of both teams will go over or under a line set by the book. Has nothing to do with who wins.

The implicit fee a sportsbook charges by pricing odds so that both sides combined imply more than 100% probability. Typical NFL/NBA moneyline vig is 4-5%; outright futures can carry 15-25%.