Think betting odds are impossible to figure out? Don’t understand what all these numbers, points, and slashes mean?
You’re not alone. If you’re new to sports betting, odds can feel like they’re written in a secret code. But don’t worry — this guide is here to make sense of it all. We’ll cover everything – from explaining what odds mean to breaking down the math behind payouts so you can bet confidently.
Let’s start with the basic question.
What do odds mean in betting?
Betting odds show how much money you can win if your bet is successful. They also tell you how likely an event is to happen based on what the bookmaker thinks.
Betting odds have been around for ages — think ancient Greece and Rome, where people wagered on chariot races and gladiator battles. Back then, it was less about profits and more about bragging rights, with odds based mostly on gut feelings and rough guesses. Eventually, smarter math and 17th-century probability theories took over, turning guesswork into the more structured system we know today.
Modern odds are expressed in different formats — decimal, fractional, and American — but they all serve the same purpose: to show your potential payout and the implied probability of an outcome.
How do bookmakers calculate odds?
Bookmakers set odds based on data, statistics, and expert opinions. Here’s a quick look at their process:
- Analyzing data: They study past performance, team form, injuries, weather, and other factors.
- Probability assessment: They estimate the likelihood of each outcome happening.
- Adding margins: Bookies include a profit margin (called the overround) to make sure they earn money no matter the result.
For example, if a bookie believes Team A has a 50% chance of winning, they’ll calculate fair odds as follows:
- Probability = 50%
- Fair odds = 100 / 50 = 2.00 (decimal format)
But to ensure profit, they might offer odds of 1.90 instead.
So, by looking at a game’s odds, you can understand this match’s favorites and how sure bookmakers (and so the public) are about their win.
But this isn’t a foolproof approach to choosing the right bet. Big events, like the Super Bowl, can get hyped up by the media, making one team seem like a bigger favorite than they really are. On the flip side, smaller events might not get enough attention, so bookies don’t always get accurate odds. And let’s be honest — sometimes they’re just too busy to tweak the numbers when something unexpected happens.
So, you can use odds as a guide (we’ll talk about it in a minute), but always bet based on information you’ve collected and analyzed.
Now, let’s learn how to read different odds formats.
Formats of odds
You can find one of the three odds formats depending on the betting platform and location.
Decimal odds
Decimal odds are widely used in Europe, Canada, and Australia. They’re the simplest to understand because they show the total payout per $1 bet, including your original stake.
This means you need to use a simple formula to calculate how much a sportsbook will pay you in total if you win:
Payout = Bet Amount × Decimal Odds
For example:
- 5.00: Bet $1, win $5 ($4 win + $1 bet)
- 5.00: Bet $5, win $25. ($20 win + $5 bet)
- 3.5: Bet 1, win 3.5 ($2.5 win + $1 bet)
So, if, say, you bet $20 on a tennis match between Serena Williams and Naomi Osaka, and Serena has odds of 3.50, you get:
Payout = $20 × 3.50 = $70 (including your $20 bet)
Profit = $70 – $20 = $50
So, decimal odds are pretty simple to understand: the bigger the number is, the more you can win, but also, the less likely the team or player is to win (in sportsbooks’ opinion).
Fractional odds
Fractional odds are more common in the UK and Ireland. They’re written as fractions (e.g., 3/1) and show the profit you’d make relative to your stake. The first number — numerator — shows how much you can win ($3) for every bet that equals the second number — denominator — ($1).
In the formula, it looks like this:
Profit = Bet Amount × (Numerator / Denominator)
You also get your original bet back, so the total payout would be:
Profit = Bet Amount × (Numerator / Denominator) + Original Bet
For example:
- 3/1: Bet $1, win $3, plus get your $1 back (total payout $4).
- 3/2: Bet $2, win $3, plus get your $2 back (total payout $5).
- 1/2: Bet $10, win $5 and get $10 back (total payout $15).
Let’s say there’s a horse race, and you bet on a horse called Lightning Bolt at 7/2 odds. If you wager $10:
Profit = $10 × (7 / 2) = $35
Payout = $35 + $10 = $45
To understand when the odds are the best isn’t that difficult here: the bigger the first number and the smaller the second, the more you can win. But when you see that the first number is smaller than the second, bookmakers believe in the team winning more and give you smaller wins.
American odds
American odds, or moneyline odds, are the most popular in the U.S.They’re shown as positive or negative numbers.
- Positive Odds (+): Show how much profit you’d make on a $100 bet, and you calculate your winning with a formula:
Profit = Bet Amount × (Odds / 100)
Payout = Profit + Bet Amount
- Negative Odds (-): Show how much you need to bet to win $100, and the formula here is:
Profit = Bet Amount × (100 / |Odds|)
Payout = Profit + Bet Amount
Let’s say there’s a basketball game between the Lakers and the Bulls. The Lakers have odds of -150. If you bet $150:
Profit = 150 x (100/150) = $100
Payout = Profit + Bet = $100 + $150 = $250
So, what does plus and minus mean in betting with these odds? Probability of a team winning.
You can understand what odds pay you better and who are game favorites with just one look: positive odds pay better but show underdogs, while negative odds point to likely winners but give lower payouts.
If you want more accuracy, you can always calculate probabilities up to the point.
Here’s how to calculate probabilities based on different odds formats.
Decimal odds to probability
Probability (%) = (1 / Decimal Odds) × 100
So, if you have decimal odds of 2.50, for example, you calculate it like this:
Probability = (1 / 2.50) × 100 = 0,4 x 100 = 40%
Fractional odds to probability
Probability (%) = Denominator / (Numerator + Denominator) × 100
Let’s say you have odds of 5/1; then your calculations go like this:
Probability = 1 / (5 + 1) × 100 = 1 / 6 x 100 = 0.1667 x 100 = 16.67%
American odds to probability
If the odds are positive:
Probability (%) = 100 / (Odds + 100)
For example, if the odds are +200, you calculate it like this:
Probability = 100 / (200 + 100) = 100/300 = 33.33%
If the odds are negative, you use this formula:
Probability (%) = |Odds| / (|Odds| + 100) x 100
Suppose you have odds of -150, then you do this:
Probability = 150 / (150 + 100) x 100 = 150 / 250 x 100 = 0.6 x 100 = 60%
But if you’re not in the mood for deep analysis and calculation, you can always wager by determining bet types: odds-against, odds-on bets, or even money bets.
Bet types by odds and probabilities
Since odds reflect probabilities (but remember they aren’t 100% accurate), by just looking at them, you can guess the winner:
- Even money bets: These odds are exactly 1/1 (2.00 in decimal or +100 in American). You double your money if you win, but in this case, it’s more difficult to guess the winner just by looking at the odds.
- Odds-against bets: These odds are better than even money (e.g., 6/1 or +200). The bookmaker thinks the event is less likely to happen, so you’d win more if it does. For example, you choose this type of bet when wagering on an underdog to win.
- Odds-on bets: These odds are less than even money (e.g., 1/2 or -150). The bookmaker believes the event will likely happen, so payouts are smaller. You choose this bet when staking on a heavy favorite to win.
It can work if you are in the mood to test your luck and have a few spare dollars to spend without regret. Just use an online odds calculator to avoid crunching numbers manually, and with crypto sport betting sites, like sportbet.one or crypto casino sportbet.one, you’ll be in the game within seconds.
Still, the best approach is to learn everything about a team or player you wager on to turn the odds in your favor, like all these lucky players who won unbelievable bets.
Crazy wins and big odds in betting history
Here are a few examples of how good odds can turn even small bets into great winnings.
Phil Mickelson – $560,000 at 28/1 odds
Pro golfer Phil Mickelson bet $20,000 on the Baltimore Ravens to win the Super Bowl at 22/1 odds. When they did, he cashed in with $560,000. What’s amazing about this win is that such high odds (and so the payout) were for a single event without using an accumulator.
Adrian Hayward – £25,000 at 125/1 odds
In 2005, Adrian Hayward bet £200 that Liverpool’s Xabi Alonso would score from his own half at 125/1 odds (crazy odds for just one event). A year later, Alonso nailed it with a long-distance shot, giving Liverpool a 5-3 win and Adrian a massive £25,000 payout.
Tayla Polia – $105,000 at 20,000/1 odds
Tayla Polia, with almost no betting experience, won $105,000 on a $5 bet. She nailed a 15-leg parlay at 20,000-to-1 odds, making one of the most improbable wins in NFL betting history.
Leicester City bet – £200,000 at 5000/1 odds
Leicester City’s 2015 Premier League victory stunned the world. Their 5000/1 odds made huge winners out of bettors, including one anonymous fan who walked away with £200,000 and another, Leigh Herbert, who turned £5 into £20,600.
Mick Gibbs – £500,000 at 1,666,666/1 odds
Roofer Mick Gibbs won £500,000 on a 15-leg accumulator bet with jaw-dropping odds of 1,666,666/1. His final win came down to a dramatic Champions League penalty shootout.
These examples show that sometimes the odds can be crazy high, but if you know how to use them in your favor, and have Lady Luck in your corner, you can become a very rich person by staking a modest bet.
Betting odds — Not so odd after all
Betting odds might seem like a mystery at first, but as you’ve seen, they’re not as complicated as they look. Odds just tell the story behind your bet — and sometimes, that story ends with a big payday. So go ahead, crunch those numbers, place your bets, and maybe your jackpot is just around the corner.
FAQ
What’s the difference between American, decimal, and fractional odds?
They’re just different ways of showing the same thing — potential payout.
- American: Uses + and – (like +150 or -200).
- Decimal: Easy to calculate, just multiply your bet by the odds to get total return (e.g. 2.50 means $10 x 2.50 = $25 return).
- Fractional: Use fractions to show probability and payouts (e.g. 5/1 means you win $5 for every $1 bet).
Depending on where you play, you’ll see odds in one of these formats.
What do plus (+) and minus (–) mean in betting odds?
These signs show the underdog and the favorite in American odds. A minus (-) means the team is favored — the number tells you how much you need to bet to win $100. A plus (+) means the team is the underdog — the number shows how much you’d win if you bet $100.
How do betting odds reflect probability?
Odds show how likely an outcome is (based on bookmakers’ opinion). Lower payouts usually mean a higher chance of winning. Example: Odds of 1.8 mean the sportsbook sees a high chance of that event happening, if the odds for the competitor are 2.5 (winning is much less likely).
