While American odds are the go-to in North America, across the pond Fractional odds—sometimes called British/UK or traditional odds—are the law of the land. They are most common among British and Irish sportsbooks, and considering how many sports betting sites originate in the British Isles, Fractional odds are worth understanding for any bettor.
Like with American odds, you always have to add on the original stake to get your total winnings when calculating Fractional odds.
Fractional odds are displayed using either a slash (/) or a hyphen (-) which can be used interchangeably. The odds would be shown as 4/1 or 4-1 and verbalized as “four-to-one odds” if being discussed out loud. Odds of 4/1 would mean that for every $1 you wager, you’re winning returns of $4 on top of your stake. The larger the numerator (or first number) is compared to the denominator (the second number), the higher the odds.
Odds of 100/1 are very high, while odds of 10/11 are quite low: for every $1 you wager on the first set of odds, you win returns of $100, while you would win just $10 for every $11 wagered on the second set of odds. If the second number is larger than the first, you’re almost definitely dealing with the favorite of the sporting event in question and therefore lower odds and less returns.
For example, if you’re betting on an MLB player to win the MVP and they have 10/1 odds, that means they’re a bit of a long shot so for every $1 you put down you win returns of $10. If you bet $20 on those odds, a winning bet would net you $200 in returns.
Basically, the equation to calculate returns for fractional odds is like this: stake multiplied by the odds. If you put down a $25 bet on odds of 10/3 your equation would be 25 x (10/3=3.33) = 83.33. So a winning bet in that instance would mean that you win your original $25 stake back as well as $83.33 in returns for a total of $108.33.