How to Read & Calculate Sports Odds
Before we can get into types of bets, let’s break down what all the weird numbers next to teams and players mean so you can start making sports bets like a pro.
What Do American, Decimal, & Fractional Formats Mean?
The numbers you see next to betting lines are called odds. The odds, displayed in either American, Decimal, or Fractional formats, serve two purposes:
- They signal the implied probability of the outcome it’s attached to.
- They indicate how much money you’ll win if you bet on that specific event.
We have to be careful with the probability though: bookmaker probabilities are influenced by where money is going, and the sum of the probabilities of a single event will always surpass 100 percent.
Bookmaker probabilities tell you how much they’re charging to take your bet. You may also hear this referred to as “the juice” or “cut” or “vig(orish).”
American Odds Explained
When you see -150, +230, or any other three-digit number with a +/- in front of it, you’re staring at American betting odds.
What Does the + and – Mean in Sports Betting?
The – and + on a sports betting line indicates both your prospective payout and whether you’re betting on the favorite or the underdog.
If the number is a -, it signifies the favorite on the betting line. The negative number indicates how much you’d need to bet to win $100.
If the number is a +, you’re looking at the underdog, and the number refers to the amount of money you’ll win if you bet $100.
The Formula for American Odds
In order to win $100 on the Penguins (favorites), you’ll need to wager $130. If you wagered $100 on the Senators (underdogs), you’d be set to win $110.
You can solve for any value you wish to wager using proportions.
If you bet $40 on Pittsburgh (-130), your equation looks like this:
Cross-multiply to get 130x = 4,000, and then solve for “x”. In case you need help with the Algebra, this would be (40×100) = 4,000, then 4,000/130. The result is 30.77.
Therefore, if you wager $40 on Pittsburgh, you will win $30.77, and your return would be $70.77 (your original wager plus your winnings).
If you bet $40 on Ottawa (+110), your equation would look like this:
If you wagered $100 on Ottawa, you’d be set to win $110, but you only want to bet $40. Simply Again, cross-multiply to get 100x = 4,400, and then solve for “x”. Therefore, if you wager $40 on Ottawa, you will win $44.00, and your total return would be $84.00.
What About Implied Probability of American Odds?
Implied probability refers to what traditional odds look like when they are converted to a percentage. Of course, if you convert the odds available at your sportsbook into a percentage, they will include the “juice” or the “vig.” Factoring in the “vig,” the implied probability of the outcome of a game will be above 100%.
Implied probability is useful because if your estimate of the probability of an event occurring is different than a sportsbooks’ you can adjust your bet accordingly.
Implied probability is useful because if your estimate of the probability of an event occurring is different than a sportsbooks’ you can adjust your bet accordingly. If the moneyline had both teams listed at -110, the implied probability would be 52.4% on both outcomes.
This would total 104.8%, and the 4.8% would account for the “vig” that the bookmaker takes on every bet. If you thought one team had a 60% chance of winning, and it was available for a 52.4% implied probability bet, this would be a smart bet.
Calculating the implied probability can be a tad trickier. We’ll start with positive odds because they are the easiest. Here is our formula:
We can calculate Ottawa’s (+110) implied probability of winning the game using this same formula. We cannot use this to calculate Pittsburgh’s, however, because they have negative odds.
Let’s substitute some numbers into our formula:
Ottawa, therefore, has a 47.6% chance of winning according to the bookmaker.
How Do Negative Odds Differ?
Take care not to get confused by all the brackets and parentheses. Their purpose is to flip the sign on the negative US odds. Here’s the formula:
When we use actual numbers, it appears far simpler. Using our example from above, we can calculate Pittsburgh’s (-130) implied probability of winning the game. Remember: We cannot use this to calculate Ottawa’s because they have positive odds.
Pittsburgh has a 56.5% chance of winning the game according to the bookmaker.
Let’s See What You’ve Learned
This time, you do the leg-work. Plug the numbers below into the formulae laid out above to answer the following questions, then check your results against the answers further down the page (no peeking!):
- Probability of San Antonio winning
- Probability of Golden State winning
- Winnings if betting $40 on San Antonio
- Return if betting $40 on San Antonio
- Winnings if betting $40 on Golden State
- Return if betting $40 on Golden State
Answers (all percentages are rounded to one decimal place):
- Probability of San Antonio winning: 12.1%
- Probability of Golden State winning: 92.9%
- Winnings if betting $40 on San Antonio: $290.00
- Return if betting $40 on San Antonio: $330.00
- Winnings if betting $40 on Golden State: $3.08
- Return if betting $40 on Golden State: $43.08
Decimal Odds Explained
Of the three types of odds you’ll encounter in your betting endeavors, decimal odds are the easiest to work with. Here’s an example of how decimal odds look:
Determining how much you will win with decimal odds is straightforward; simply multiply your wager by the odds associated with the team you are betting on:
What About Implied Probability?
To figure out the implied probability, follow this formula:
Implied Probability: 1 / Decimal Odds
Using our example from above, the following equation is Tampa Bay’s implied probability of winning:
Implied Probability: 1 / 2.40 = 41.7%
And Cleveland’s chances of winning:
Implied Probability: 1 / 1.61 = 62.11%
Fractional Odds Explained
Let’s finally move onto fractional odds, which are most common in the UK, as well as horseracing.
These are the funny-looking odds – like 9/5 or 1/2 – that you see when you flip on the Kentucky Derby
These are the funny-looking odds—like 9/5 or 1/2—that you see when you flip on the Kentucky Derby. The first thing to know is that, if you want to say fractional odds, like 9/5 or 1/2, aloud, you would say “nine to five” or “one to two.”
The number on the left (9) dictates how many times the relevant outcome could fail; whereas the number on the right (5) tells us how many times the outcome would succeed.
Fractional Odds in Action
Let’s say Golovkin hypothetically receives the 8/13 odds. These odds mean that, if this fight happened 21 times (8 + 13), Golovkin would lose 8 bouts and win 13.
To calculate the implied probability of Golovkin winning the fight, take the number of times he is expected to win (13) and divide it by the total number of trials (21). This results in a 61.9% chance for Golovkin to win the fight.
The formula, plus what it looks like after we input Golovkin’s odds:
To calculate Alvarez’s probability of winning the match, we do the same thing. Let’s say, hypothetically, odds are 11/8, meaning if the fight happened 19 times (11 + 8), Alvarez would lose 11 times and win 8 times.
Therefore, the probability of Alvarez winning the fight is calculated by dividing 8 (the number of times he would win) by 19 (the total number of trials). Alvarez has a 42.1% chance of winning the fight.
Our formula would look like this:
Remember what we said earlier about the “juice” or the “vig”? This is the cut the bookmakers take. It means that that the implied probabilities of both outcomes added together is going to be greater than 100%.
We haven’t even factored in the probability of a draw yet, and the sum of the probabilities is already over 100% (61.9 + 42.1 = 104). You’ve got to pay to play, unfortunately.
If you want to bet on Golovkin to win the fight (8/13 odds), your winnings are calculated by multiplying your wager by the quotient of 8 ÷ 13 (0.615). If you wish to bet $10, then your winnings will be $6.15 (10 x 0.615). That number is added to your wager (your “return” or how much money you receive back). In this case, you’ll receive $16.15 back ($10 + $6.15).
Here’s what the formula looks like, plus what it would look like after we input Golovkin’s odds:
If you want to bet your $10 on Alvarez, multiply that sum by the quotient of 11 ÷ 8 (1.375). Your winnings would be $13.75 ($10 x 1.375).
Your return would be $23.75 ($10 initial stake + your winnings of $13.75). Below is how to solve that using the formula.
There is a greater payout when betting on Alvarez, the “underdog” in this fight. Betting on underdogs in any sport typically allows you to risk less in order to win more. Remember, however, that there’s a reason they are the underdog, whether it’s a rookie season, there’s been a recent injury, or they face serious competition.
If you side with Golovkin, the “favorite,” you’ll need to risk more to get the same return.
Let’s See What You’ve Learned
Just like we did with American odds, use the formulae you’ve learned (and the fractional odds below) to answer the following questions:
- Probability of Real Madrid Winning:
- Probability of a Draw:
- Probability of Juventus Winning:
- Winnings if betting $10 on Real Madrid:
- Return if betting $10 on Real Madrid:
- Winnings if betting $10 on a Draw:
- Return if betting $10 on a Draw:
- Winnings if betting $10 on Juventus:
- Return if betting $10 on Juventus:
Answers (all percentages are rounded to one decimal place):
- Probability of Real Madrid Winning: 36.4%
- Probability of a Draw: 31.3%
- Probability of Juventus Winning: 35.7%
- Winnings if betting $10 on Real Madrid: $17.50
- Return if betting $10 on Real Madrid: $27.50
- Winnings if betting $10 on a Draw: $22.00
- Return if betting $10 on a Draw: $32.00
- Winnings if betting $10 on Juventus: $18.00
- Return if betting $10 on Juventus: $28.00
What Is a Push?
While not technically related to odds, a push will definitely affect your payout. Before they start betting on sports, every bettor should be aware of the possibility of a push.
Simply put, a push is a tie. You will not see pushes when betting on money lines because—if a sport allows a game to end in a tie—a tie or draw will be a possible outcome you can bet on.
A push only concerns you when you are betting against the spread or placing a totals bet.
If a push does occur, you will simply be refunded your money. It will not count as a win or a loss.
You will occasionally see a spread or total that does not feature a half-point, in order to avoid the possibility of a tie. Here is an example:
If this game were to end 20-18 for Cincinnati, neither team covered the spread and will be considered a push. In this circumstance, you’d be given your money back like the bet never happened.
If you have a four-team parlay (and only one game pushes), most sportsbooks will simply reduce the parlay to three teams. Be sure to know your sportsbook though, as some deem the entire parlay a loss. The same goes for a teaser, as well.
Now that you’re an expert in reading sports odds, get out there and start winning some money!