Bookmaker

Definition

A bookmaker (also called bookie or sportsbook) is a licensed company that sets odds on sporting events, accepts wagers from bettors, and pays out winnings. Bookmakers make their profit through the margin (vig) built into their odds, ensuring they collect slightly more from losers than they pay to winners over time.

How It Works

Bookmakers employ teams of odds compilers and use algorithmic models to set initial odds that reflect the true probability of each outcome, plus a margin for profit. As bets come in, they may adjust odds to balance their liability. The goal is to create a "balanced book" where they profit regardless of the outcome, though in practice, bookmakers often take positions on certain results.

Example

A bookmaker offers odds on a tennis match:

• Player A: 1.80 (implied probability 55.6%)
• Player B: 2.10 (implied probability 47.6%)
• Combined: 103.2% -- the extra 3.2% is the bookmaker's margin

For every $103.20 wagered across both outcomes, the bookmaker pays out $100 regardless of who wins, keeping $3.20 as profit.

Why It Matters

Understanding how bookmakers operate is fundamental to profitable betting. Different bookmakers offer different margins, odds, and limits. "Sharp" bookmakers (like Pinnacle) offer tight margins but limit winning accounts quickly. "Soft" bookmakers offer worse odds but more promotions and higher limits initially. Having accounts at multiple bookmakers lets you shop for the best odds on every bet -- a practice called line shopping that directly improves your bottom line.