A sports betting odds ratio refers to implied probability, as in how likely an outcome is to happen based on the betting odds. There are formulas to follow based on the direction that the numbers are going.
Negative odds: Odds/(Odds+100)*100
Positive odds: 100/(Odds+100)*100
As you can see, the formula for negative numbers begins with the odds, while the formula on the positive side always begins with 100. After you work through the formulas a few times, you’ll find they’re not all that complicated. Even better, they can help to improve your understanding of the likelihood of outcomes.