Sports Betting Odds Explained: How They Work in Sports
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Last Updated: 17 December, 2025
Odds tell you two things: how likely something is to happen, and how much money you can win if it does.
Whether you're using American, Decimal, or Fractional odds, the goal is the same: to understand your potential payout.
This quick guide breaks down each odds format with examples, so you can bet smarter on your sportsbook of choice.
Here is a simple table laying out the basic aspects of each type of sports betting odds:
Understanding Fractional Odds
Fractional odds (or British odds) are the most commonly used odds, typically written with a slash or a hyphen. For instance, they can be written either as 5/1 or 5-1 and pronounced: “five-to-one”.
That said, if you have “five-to-one” odds of winning, it would mean that you’d get back your stake (for example, $1) and your stake multiplied by the odds as profit (in this case of $5) – $6 in total if you win the bet.
If you have odds aligned as follows – team X: 10/11, team Y: 9/5, and team Z: 6/1 – it’s easy to determine that team X is the favorite, while the remaining teams are thought to be less likely to win the game.
On the other hand, these odds mean that betting on one of the other two teams might bring a more financially tempting prize.
With good reason – it’s less likely they’ll win. In other words, size up your chances before placing any money!
Understanding Decimal Odds
Decimal, or European odds, are usually easy to understand.
Underdogs and favorites can be spotted instantly, just by looking at the numbers.
The logic is simple:
The odds show every dollar won for every dollar invested, taking into consideration the total payout, stake included.
To calculate your potential winnings, just multiply the stake by the odds.
For instance, if we have a bet like this – X: 4.0 and Y: 1.3 – you would get $4 if you bet $1 on X, and $1.3 if you bet on Y. Since the quota for Y is lower, we can deduce that Y is more likely to win.
Understanding American Odds
American odds are, obviously, popular in the United States.
The odds for favorites are preceded by a minus sign, showing the amount you need to stake to win $100.
Underdog odds will have a plus sign in front of the amount, showing how much every $100 winning stake gets.
Don’t worry – whichever team you favor, winning means you get back both the money you bet and the money represented in the odds.
For instance, if we have the odds X: +585 and Y: -760, those who place a $100 bet on X will get $685 in case they guess right, while those who bet on Y will need to bet $760 to win $100, for a total payout of $860.
How to choose the best sports betting odds
No matter how confident you are in your pick, getting the best possible odds matters.
Even small differences in odds can impact your profit over time, especially if you place bets regularly.
Why odds shopping matters
Different sportsbooks can offer slightly different odds on the same event.
That difference might look small, but over dozens of bets, it adds up.
Example:
Let’s say you're betting on the same NBA game across three sportsbooks:
Sportsbook A: Knicks -3 (-110)
Sportsbook B: Knicks -3 (-115)
Sportsbook C: Knicks -3 (-105)
If you win a $100 bet:
At -110, you win $90.91
At -115, you win $86.96
At -105, you win $95.24
That’s an $8 difference on a single bet. Now multiply that over a season’s worth of wagers.
How to find the best odds - Our top tips
Compare at least 2–3 sportsbooks before placing a bet. Open multiple apps or tabs to check.
Look for promos like boosted odds or reduced juice. These can instantly improve your payout.
Stick with licensed sportsbooks. Legal platforms post consistent and fair lines.
Track your bets. Use a spreadsheet or app to see how small odds edges add up over time.
Use odds comparison tools. Some sites automatically show the best line across books.
Odds shopping is one of the easiest ways to get better value without changing how you bet.
It’s a smart habit that separates casual bettors from sharper ones.
How to place a bet
Placing a bet isn’t complicated once you know what to expect.
Here’s a step-by-step guide using a typical legal sportsbook app:
How to use odds to calculate probability?
American odds are a popular way to express betting odds in the United States.
They can be either positive or negative, and the way they are interpreted depends on this sign.
Here's how you can calculate the probability from American odds:
Positive American Odds
For positive odds (e.g., +200):
Probability = 100 / (American Odds + 100)
Negative American Odds
For negative odds (e.g., -150):
Probability = -American Odds / (-American Odds + 100)
Examples
Positive American Odds (+200)
Using the formula for positive odds:
Probability = 100 / (200 + 100) = 100 / 300 ≈ 0.3333
So, the probability is approximately 33.33%.
Negative American Odds (-150)
Using the formula for negative odds:
Probability = 150 / (150 + 100) = 150 / 250 = 0.6
So, the probability is 60%.
Converting probability to American Odds
For a probability greater than 50% (i.e., a favorite):
American Odds = - (Probability * 100) / (1 - Probability)
For a probability less than 50% (i.e., an underdog):
American Odds = ((1 - Probability) * 100) / Probability
How to read line movement
Line movement shows how betting odds shift after they're released.
These changes can tell you where the money is going and help you make smarter decisions.
Why do lines move?
Sportsbooks don’t just post odds and leave them. They adjust them based on:
Public betting pressure: If most bets are landing on one side, the book may adjust the odds to balance risk. For example, if heavy action hits the Eagles at -110, the line might move to -125 to slow down that side and attract money on the opponent.
Breaking news: Injuries, weather, or lineup changes can cause fast shifts. If a star QB is ruled out, the underdog might move from +140 to +110 within minutes.
Sharp money: Professional bettors (or "sharps") can influence lines when they place large, early wagers. Books often react quickly to this type of action, even before the public sees it.
What line movements mean
Let’s say a team opens at -110 and later moves to -125. That shift means:
You now have to bet $125 to win $100, instead of $110.
The oddsmaker believes the team is more likely to win, or they’re getting too many bets.
It doesn’t guarantee an outcome, but it signals where the money (and possibly the value) is.
How to use it
Watch for quick shifts in odds, especially right after opening.
These can point to sharp money.
Use multiple sportsbooks to compare odds and spot value before or after the line moves.
If you're confident early, betting before the line moves might save you money.
If you're uncertain, waiting could give you a better number on the other side.
Odds by sport
Odds aren’t just about numbers, they reflect how each sport is structured.
Different sports use odds in different ways, and understanding these differences can help you make more informed bets.
NFL & NBA betting odds
In the NFL and NBA, most sportsbooks use three main bet types: point spreads, moneylines, and totals (over/unders).
Point spread: Levels the playing field by giving the underdog points. For example, if the 49ers are -6.5 favorites against the Seahawks, they need to win by 7 or more for your bet to win. If you bet on the Seahawks at +6.5, they can win outright or lose by 6 or fewer.
Moneyline: A straight bet on who will win. A favorite might be listed at -150 (you bet $150 to win $100), while the underdog is +130 (a $100 bet wins $130). The closer these numbers are, the tighter the matchup.
Totals: Bet on the combined score of both teams. If the total for Lakers vs. Celtics is 214.5, you’re betting whether the final combined score will be over or under that number.
MLB betting odds
Baseball uses a unique format called the run line, which works like a spread but is usually fixed at 1.5 runs.
Run line: Dodgers -1.5 (+120) vs. Mets +1.5 (-140). If you bet on the Dodgers, they must win by 2 or more. Betting on the Mets means they can win outright or lose by just 1 run. Unlike other sports, odds vary more due to the low-scoring nature of baseball.
Moneylines are common, too, especially when betting on pitchers. A strong pitcher matchup can swing odds dramatically.
Totals in baseball are usually low, between 7 and 9 runs, and factor in starting pitchers, ballparks, and weather.
NHL betting odds
Like MLB, hockey uses a fixed puck line of 1.5 goals.
Puck line: Maple Leafs -1.5 (+145) vs. Canadiens +1.5 (-165). To cover the puck line, Toronto must win by 2+. Betting on Montreal means they can lose by 1 or win outright.
Moneylines dominate the NHL, especially for close games.
Totals are low, often around 5.5 or 6 goals, due to the tight nature of hockey scoring.
UFC & MMA odds
UFC betting is moneyline-heavy, but it also has some of the most creative prop markets.
Moneyline: Amanda Nunes -300 vs. Julianna Peña +250. You must bet $300 on Nunes to win $100, while a $100 bet on Peña would win $250 if she pulls the upset.
Round betting: Predict the winner and the round the fight ends in. For example, “O’Malley to win in Round 2 (+500).”
Method of victory: Choose whether a fighter wins by KO, submission, or decision.
These markets reward bettors who closely follow fighters’ styles and history.
College football & basketball odds
College sports use the same format as the NFL and NBA (spreads, moneylines, and totals) but with more volatility.
Point spreads can be large in college football due to mismatches. A top team might be -28.5 over a lower-ranked school.
Totals are often higher in college basketball (e.g., 150.5 points) due to faster play and less defense.
College teams can be more inconsistent, so line movement is common. Keeping up with injury news or lineup changes can give you an edge.
Wrapping up
Now that you understand how betting odds work, whether American, fractional, or decimal, you’re better prepared to make informed bets, not just guesses.
You’ve seen how to spot favorites and underdogs, calculate payouts, and even interpret line movement.
Before placing any wagers, make sure you’re using a legal, licensed sportsbook that operates in your state.
This keeps your funds safe and ensures fair odds.
We’ve reviewed and compared dozens of platforms, see our picks for:
Best sports betting sites - ranked by odds, features, and ease of use
Best sports betting apps - top-rated options for mobile betting
And as always: bet with your head, not your heart. Set a budget, stick to it, and play responsibly.