Chapter 1: Introduction to Sports Betting · Lesson 1
By Cadell Griffith, Software Architect and founder of OddsFantasy · Updated · 4 min read
Sports betting is placing money, your stake, on an outcome of a sporting event at odds set by a bookmaker or by other bettors. If the outcome happens you are paid stake × odds; if it doesn’t, you lose the stake. A $100 bet on over 3 goals in Real Madrid vs Manchester City at 2.35 returns $235 if four or more goals are scored.
By the end of this lesson, you will be able to:
If you watch sports, you’ve seen betting ads everywhere. Sports betting looks complicated from the outside, but every bet, from a $5 single to a ten-leg accumulator, is built from the same six parts.
Sports betting is placing a monetary stake on the outcome of a market in a sporting event, at the odds set by a bookmaker.
A $100 wager on Pinnacle for the total goals in Real Madrid vs. Manchester City to go over 3 at odds of 2.35.
| Part | In this bet |
|---|---|
| Stake | $100 |
| Event | Real Madrid vs. Manchester City |
| Market | Total goals |
| Outcome | Over 3 |
| Odds | 2.35 |
| Bookmaker | Pinnacle |
Keep these six pieces in mind: stake, event, market, outcome, odds and bookmaker. They describe any sports bet you’ll ever place.
For the Real Madrid bet: four or more goals pays $235, exactly three goals refunds your $100, two or fewer loses it.
Decimal odds are a multiplier: payout = stake × odds, and the payout includes your stake.
| Stake | Odds | Payout if it wins | Profit |
|---|---|---|---|
| $100 | 1.50 | $150 | $50 |
| $100 | 2.35 | $235 | $135 |
| $100 | 4.00 | $400 | $300 |
Higher odds pay more because the outcome is less likely: odds of 4.00 imply a 1 ÷ 4.00 = 25% chance. You’ll calculate payouts in detail in how to calculate a betting payout.
| Bet type | How it works | Example |
|---|---|---|
| Single | One selection; wins if that outcome happens | Real Madrid to win at 1.80 |
| Accumulator (parlay) | Several selections in one bet; all must win, and their odds multiply | 1.80 × 1.90 = 3.42 for a two-leg accumulator |
| Live (in-play) | Placed after the event has started, at odds that change as it plays | Over 1.5 goals at half-time |
| Exchange or prediction market trade | You buy a position from other bettors and can sell it before the end | A Polymarket share at $0.40, odds of 2.50, that pays $1 if the outcome happens |
Every type uses the same six parts. Accumulators are covered by the accumulator calculator, and trading in sports trading on OddsFantasy.
A bookmaker doesn’t need to predict winners. It prices every outcome slightly below its fair value, so the implied probabilities of a market add up to more than 100%, and it keeps the difference. Price a coin toss at 1.90 instead of 2.00 on each side, take $100 on each, and the bookmaker pays out $190 and keeps $10 whatever happens. You’ll build exactly that book in what is bookmaking.
That margin is why most bettors lose over time, and beating it is what the rest of this course teaches.
It depends on where you live. Many countries license bookmakers and allow betting from age 18 (21 in some US states); others restrict it or ban it. Check the law where you live, only bet with licensed bookmakers, and only bet money you can afford to lose.
In the next lesson, you’ll look at the main reasons people bet and work out which apply to you, which shapes everything from your stake size to the bets you choose.
Sports betting is placing money, your stake, on an outcome of a sporting event at odds set by a bookmaker or by other bettors on an exchange. If the outcome happens you are paid stake × odds; if it doesn't, you lose the stake.
A bookmaker sets odds on the outcomes of an event. You choose an outcome and a stake, and the bet is fixed at the odds you took. When the event ends the bet is settled: a win pays stake × odds, a loss costs the stake, and a push on a whole-number line refunds it.
With decimal odds, payout = stake × odds and profit = stake × (odds − 1). A $100 bet at 2.35 pays $235 if it wins: your $100 back plus $135 profit.
Singles (one selection), accumulators or parlays (several selections that must all win, with their odds multiplied), live or in-play bets placed during the event, and trades on exchanges and prediction markets, where you can buy and sell a position before the event ends.
They build a margin into their odds, so the implied probabilities of a market add up to more than 100%. On a coin toss priced at 1.90 each side, $100 on each side leaves the bookmaker $10 whichever side lands.
It depends on where you live. Many countries license bookmakers and allow betting from age 18 (21 in some US states), while others restrict or ban it. Check the law where you live and only bet with licensed operators.