How do odds work
Betting odds is a numerical multiplier that expresses the probability of a particular event in a sporting event and includes a bookmaker's margin. The odds give the player an idea of what the potential winnings of a bet are
The odds can change both due to the change in the probability of the event, and due to the "overloading of the line".
Decimal (European) odds
In Europe, Kenya, and CIS countries, and in some Asian countries, the decimal odds are widespread.
The decimal coefficient multiplied by the bet amount allows you to know the amount of potential payout. For example, a $100 bet at odds of 1.91 has a potential payout of $191 (100 x 1.91). Of that, $91 is the net profit and $100 is the bet amount.
To convert a bookmaker's decimal odds to a percentage probability of the event plus the margin, you must divide 100 by the value of the odds. Example: 100/1.75 = 57, which means the probability with the margin is 57%.
Fractional (British) odds
Fractional or British odds are widely used in bookmakers' offices in Great Britain and some other countries.
Fractional odds are the ratio of the amount of potential net profit (numerator) to the amount you need to bet to get such a profit (denominator). For example, a fractional multiplier of 5/3 tells a player that for every $3 bet, he will get $5 in net profit if the bet wins.
To convert a fractional ratio to a decimal ratio, divide the numerator by the denominator and add 1 (one). For our example: 5 / 3 + 1 = 2.66. Another example: 40 / 1 + 1 = 41,0.
There are two kinds of American odds: positive and negative (e.g., +120 and -140).
The value of a positive American odds is the amount of potential net profit at a bet of 100 conventional units. For example, a +120 odds means that for every $100 bet a player can get $120 of net profit.
The negative American odds value is the amount that must be wagered to win 100 conventional units. For example, odds -140 means that you need to bet $140 to get a $100 net profit.
To convert a positive American odds to decimal, divide its value by 100 and add one. For our example: 120 / 100 + 1 = 2.20.
To convert a negative American ratio to a decimal, divide 100 by its value (without the minus sign) and add one. For our example: 100 / 140 + 1 = 1.71.