Odds are a mathematical way of expressing the chances of an event occurring. Like probability, they are expressed as ratios; for example, the odds that a particular day will occur during the weekend are two to five (2:5). The inverse of the odds that an event will not occur is also known as the odds against, and these are calculated by dividing the number of favorable outcomes by the number of unfavorable ones.
When you place a bet on sports, odds will tell you how likely it is that a team will win. This can be expressed in American, fractional or decimal odds, and knowing how to interpret each is an important step in putting together a winning betting strategy.
For bettors in the United States, betting odds are often presented using American format – a single number with a trailing slash (e.g. 4/1 or 1 / 5). This is the format most commonly used for football and other US sports betting, and it is relatively easy to understand, with the number indicating how much money you will earn if your selection wins.
If you are betting on horse racing or other sports in Europe, Australia or New Zealand, you will probably encounter fractional odds. These are more complex to calculate, but they can be translated into an equivalent American format by multiplying the odds of one event by the odds of the other, as follows: