In fixed odds betting, the odd assigned to the outcome of an event goes to mathematically determine the probability of that particular outcome for the event in question.
Each odd has a subjective value, and it is assigned by the bookmaker after statistical analysis and using specific knowledge and information.
For example, let’s take a football match and the odds associated to its final outcome:
1 
X 
2 

JuventusFiorentina 
1,9 
3,4 
4 
The lower the odd assigned to the outcome of an event (for example the victory of Juventus), the higher the probability for that outcome to occur. In order to calculate the probability in a percentage you should divide 100 by each odd (ex. 100/1,9 = 52.6), getting these values:
1 
X 
2 

JuventusFiorentina 
52,63 
29,41 
25,00 
The sum of the three odds will give you a value greater than 100 called “overround”. This value represents the potential profit that every bookmaker retains while determining the odds. In this case: overround 107,04
This means that the real probability associated with the victory of Juventus, draw and the victory of Fiorentina can be obtained by dividing the 3 probabilities by the overround: for example, the probability in percentage for the victory of Juventus should be calculated as follows:
107,04 : 52,63 = 100 : X as a result: X = 49,1%.
1 
X 
2 

JuventusFiorentina 
49,1% 
27,5% 
23,4% 
The potential Payout associated with that event (the one that a player would win after placing a bet on all the possible outcomes of the event, in proportion to the odds) will be 93,42% (100/overround).
Provider 
Average annual Payout 

Casino Vip 
from 95% to 98% of the total 
Play Better 
from 92,80% to 98% of the total 
F1x2 
from 93% to 96% of the total 
Game Art 
from 96% to 97% of the total 
Live Casino 
Roulette: 97,30%  Baccarat: 98,94%  BlackJack: 99,73% 
Example: 95% of win probability means that 95% of the amount played on an specific product will be returned to different players in some form of winnings.