When you begin into the sports betting online, your first doubt occurs right from the beginning, “what odds are?”. Basically, an odd is a probability. The number appearing for designate that odd, shows also what is the value you may win for betting in a specific event or result. On traditional bookmakers, such as Bet365, the odds are established by experts, in which it represent an odd of a specific event occurring. Odds are calculated based on statistical data, teams’ data and a series of other relevant data regarding upcoming matches or events.

In a bet exchange, such as Betfair, odds works in a different manner. Since Betfair is a betting exchange, odds values are established accordingly to bets volume performed between several players. It is the own bettors’ community that, directly or indirectly, defines odds’ values for that specific event or result.

In general, an odd’s value is inversely proportional to the winning estimated odd. This means that if you bet in favour of a team that has a low odd, it means it has a higher probability to win. The same happens if you bet in a team that has an odd to high, where the probability of winning is consequently very low.

## Different odds type

Usually, a traditional bookmaker offers three different type of odds, based on the different international betting markets: the decimal, the fractional and the american odds format. To better and easily understand how do these odds’ types work, lets analyse in detail each one.

## Decimal or European odds

A decimal odd is the most common in the sport bookmakers, for being an European origin odd. Generally, it is a integer or a decimal number. In order to calculate a decimal odd, you have to divide 1 for the winning odd. If you enter into a bookmaker, there are available several odds for matches and events that you intend to determine how much you can win by betting in a certain result. For that, the formula to use is the following:

Probability = 1 / odd. To calculate the profit (W), you will have to use the following formula: W = betting amount * (odd  1)

To better understand how does a Decimal Odd works, lets check the following example of a Championship League match between Arsenal and AC Milan:

• The Arsenal winning odd is set in 2.30. If you bet for Arsenal your profit will be [£1 * (2.30-1)] = £1,30.
• The odd for teams draw is set in 3.40. If you bet £1 in the draw, your profit will be [£1 * (3.40-1)] = £2,40.
• The AC Milan winning odd is set in 3.00. If you bet for AC Milan, your profit will be [£1 * (3.00-1)] = £2,00.

## Fractional or English odds

The fractional or English odd is most common in the British bookmakers, and have a fractional format. The numerator indicates the profit units, while the denominator represents the betting units. In order to calculate the Profit (W), you should use the following formula: W = Betting amount * odd

For you to better understand how does this method works, lets analyse the exact same example as the Championship League match between Arsenal and AC Milan:

• The winning odd for Arsenal is set in 13/10. If you bet £1 for the Arsenal win, your profit will be  [£1 * 13/10 =] £1,30.
• The teams draw is set in 12/5. If you bet £1 for teams draw, your profit will be  [£1 * 12/5 =] £2,40.
• The winning odd for AC Milan is set in 2/1. If you bet for the AC Milan win, your profit will be [£1 * 2/1 =] £2,00.

## American odds

The American odds is one of the most frequently used in the American bookmakers. Usually, the odd has a positive or a negative value. Typically, these odds are created for american events, such as the Baseball, American Football, NHL, and many others. The negative odds indicates how much it is required to bet in order to get a benefit of 100 units, and the positive ones show the respective benefit for a 100 units bet. In the decimal format, the positive bets higher than 2.00 and the negatives the lower than the own bet. The formulas to use are the following:

For negative odds: W = Betting amount * 100 / odd.

For positive odds: W = Betting amount * odd / 100.

In order to fully understand how does the American odds functions, lets, once again, rely on the Championship League match between Arsenal and AC Milan:

• The winning odd for Arsenal is set in +130. If you bet £1 for the Arsenal win, your profit will be [£1 * 130/100 =] 1,30 Euros.
• The teams draw is set in +240. If you bet £1 for teams draw, your profit will be  [£1 * 240/100 =] £2,40.
• The winning odd for AC Milan is set in +200. If you bet for the AC Milan win, your profit will be [£1 * 200/100 =] £2,00.

## Odds classification

On the contrary of most bettors might think, not all odds are good for sports betting. There are the called “too low odds”, that should be avoid, since its risk do not make up its gains. When we find a too low odd, you should think seriously of not placing that stake, since you will be forced to bet lots of money in order to get an interesting minimum profit. When you bet in “too low odds”, the profit tends to be reduced, which means that of you lose the bet, losses will be higher that almost all gains.

• 1,01-1,14. Too low odds
• 1,15-1,49. Low odds
• 1,50-1,99. Medium odds
• +2. High odds

Having this scenario in mind, the best is to bet in medium or high odds, since its risks overcome its potential gains. One of the most common systems used by bettors is the Martingale Method, that, for instance, should be applied in medium and high odds, to avoid excessive losses.