Sports Betting Basics: Odds, Markets and Settlements

Every sports bet is a price for a probability. Learning to read that price - and to understand how the margin is applied - is the foundation of everything else.

Three ways to write the same price

Decimal odds express the total return per unit staked, so 2.50 returns 2.50 for every 1.00 including the stake. Fractional odds express the profit only, so 3/2 means a profit of 1.50 per 1.00 staked. American odds use a plus or minus sign: +150 means a 100 stake returns 150 profit, while -200 means you must stake 200 to win 100.

All three describe identical probabilities. Converting between them is arithmetic, and the implied probability is simply one divided by the decimal odds.

The overround, or how the bookmaker earns

Add up the implied probabilities of every outcome in a market and the total exceeds 100%. The excess is the overround or margin, and it is how a bookmaker is paid regardless of the result.

A two-way market priced at 1.91 and 1.91 implies 104.7% in total, so the margin is 4.7%. Sharper markets, particularly on major football leagues and high-liquidity events, run margins of 2% to 4%. Comparing margins across operators for the same market is the fastest way to reduce your cost of play.

Market types and settlement

A market is a question with a set of possible answers. Match winner, total goals, correct score, first goalscorer and handicap lines are all markets on the same fixture, each with its own pricing and its own risk profile.

Settlement rules matter as much as odds. A bet on 'to win' normally loses on a draw, while a 'draw no bet' wager refunds the stake. Some markets are settled at ninety minutes and exclude extra time, and others include it. Checking the rules before placing a bet prevents most disputes.

Frequently asked questions