Sports betting American Football odds American, Fractional and Decimal Odds

December 27, 2022

For those new to sports betting, some things on a bet slip or app may need to be clarified. One of the most significant things to know is how betting odds work & what they mean. First, odds express in a few different ways, and the numbers mean very other things depending on the system used by the sportsbook. There are three common ways of expressing odds: American, fractional, and decimal.

American Odds

The odds for the Americans are confused on their faces. They are more complex than decimal or fractional odds. American odds are around $100, but their relationship to $100 depends on whether the bet is favorable. For best Bets, betting odds start with a negative number, telling you how much you need to bet to win $100. If the odds are -110, a standard number involved in spread betting, you would need to wager $110 to win $100. If your odds are -200, you need to wager $200 to win $100. Of course, the stakes can be smaller, but the ratio will increase or decrease. Betting $10 at -200 odds will give you $5 plus your original $10 bet.

Odds with a plus sign are loser bets. Sided odds tell you how much profit you will make on a $100 Bet. Betting $100 at odds of +200 will give you a $200 profit plus your original $100 Bet. If you bet $20, you will make $40.

It can list as -100, +100, or EV for rare even odds.

Let’s see how this works in a real game.

Green Bay Packers
O 52
Seattle Seahawks
U 52

If you bet on their odds, the Celtics and Lakers are both -110 in this game. The same goes for either side (over/under) of the total score. A money line is a different place. A 250-dollar bet on the Celtics on the money line means that if they win the match by any margin, the bet wins and will win $100 (plus a return of the original $250 Bet). Bet $25 and win $10.

The Lakers are the underdogs, so they have more odds. A $100 bet will win $280 in addition to the initial 100-dollar bet.

Fractional odds

Decimal & fractional odds are more common outside of the US but can also find in some US sportsbooks. Both have similar principles.

As the name suggests, odd fractional displays as fractions, such as 3-1 or 7-4. Multiplying the bet amount by the score will show the profit. Betting $10 at 3-1 odds, you’ll make $30 in profit and $10 back.

Betting $10 at odds of 7-4 would net you $17.50 plus the original $10. Multiply $10 by the numerator, in this case, 7, and divide by the denominator, 4. It gives you 70 divided by four, or 17.50.

A favorite has a denominator greater than the numerator, such as 1-2 or 2-5. As in the example above, the numerator of the loser bet will be greater than the denominator.

Fractional odds are typically used in futures betting in the US, where almost all odds have a denominator of 1 and are, therefore, easier to understand.

Kansas City Chiefs
Green Bay Packers
Tampa Bay Buccaneers
Baltimore Ravens
Buffalo Bills
San Francisco 49ers
New Orleans Saints
Seattle Seahawks
Los Angeles Rams
Cleveland Browns
Dallas Cowboys
Indianapolis Colts
Miami Dolphins
Tennessee Titans
Los Angeles Chargers


Decimal odds

Decimal odds display as a number, the winning bet amount on a $1 bet. If the odds list as 6, the winning Bet would have a $5 profit and the original $1 Bet. Anything between 1 and 2 is the favorite Bet, with 2 being an even money bet.

These are more commonly used outside of the US when the fractions used in fractional odds get a little ugly. For example, American odds of -115 are relatively common but convert to 20-23 in fractional odds. Please quickly calculate the return on a $10 bet with odds of 20-23. Ok. The decimal odds will be listed as 1.87, making the math easier for this $10 bet. Multiply the odds by the Bet, and you’ll get a return that includes your original Bet. So much easier. The return is $18.70. In this case, decimal odds may be better.

Convert odds to breakeven percentage

However, they present that converting your odds into a breakeven percentage is a Key part of understanding what makes a good bet. If the odds are +200, the book gives you odds a third of the time. If you think the odds are higher than that, it’s a good choice. It is similar to pot odds in poker, for example.

Think of flipping a coin. There’s a 1 in 2 chance of heads coming up. It is a good bet if your odds are better than 1 in 2. Usually, you will know the exact odds as sporting events are unpredictable, but this is a Key principle to keep in mind when evaluating bets, especially on money lines.

This principle can apply if you have a projective model, such as the Slingshot model used to predict NCAA men’s basketball tournament upsets. The slingshot has a certain chance of accidents. Once you convert the odds to a percentage, the percentage compares to the winning odds. If the model believes the odds are significantly better than the betting offers, and you trust the model, this can be a helpful tool in deciding whether to place a bet.

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