Understanding Craps Probability
For all intents and purposes, Craps whether played at a land based or online casino, is a game of chance. There are hundreds of websites out there that will insist differently as they attempt to sell you a craps system or strategy that works 100% of the time, but the truth is that this doesn't exist.
What is a reality is the fact that craps, like all other forms of gambling is based on mathematics, and the probability factor which we will explain as we go in the hope of assisting you to determine how best to play the game.
The game of Craps is played with two dice and offers 8 main ways in which to place your bets on the Craps table. Due to the fact that rules differ depending on the Craps variation you are playing, you are not always able to place all of the best. Keeping that in mind, you also need to be aware of the fact that there are also odds bets which carry a lower house edge based on the odds of obtaining a specific outcome rather than on a certain bet. These bets replace the come and pass bets in certain variations of the game.
When looking at a Craps Probability table, you will be able to determine the frequency with which certain outcomes occur and how much you stand to earn from these types of bets. For example if you would like to achieve a sum of two, the table indicates which combinations would be necessary.
Occurrences 
Sum 

Sum 
Occurrences 

1  2 
(1,1) 
(1,2) 
(1,3) 
(1,4) 
(1,5) 
(1,6) 


2 
3 
(2,1) 
(2,2) 
(2,3) 
(2,4) 
(2,5) 
(2,6) 
8  5 
3 
4 
(3,1) 
(3,2) 
(3,3) 
(3,4) 
(3,5) 
(3,6)  9  4 
4 
5 
(4,1) 
(4,2) 
(4,3) 
(4,4) 
(4,5) 
(4,6) 
10 
3 
5  6 
(5,1) 
(5,2) 
(5,3) 
(5,4) 
(5,5) 
(5,6) 
11 
2 
6 
7 
(6,1) 
(6,2) 
(6,3) 
(6,4) 
(6,5) 
(6,6) 
12  1 
Let's look at the combinations which make up the sum of 2 and you'll find that there is only one way to achieve the sum of two (ie. 1 plus 1). You'll notice however, that the likelihood of achieving other sums like for example 4 have many more combinations which can achieve this. The table also includes an examination of the occurrence for the numbers to appear on the die. In other words for the chance of getting a 1 there are 6 possible outcomes. The sum section indicates the total that can be achieved for the occurrence of certain dice.
For example if you look at the 8 in the sum column on the table you'll see that the sum of 8 can be made up when throwing a 2 and 6 but there are also 5 other occurrences that may achieve an 8. To see these, begin at the (2,6) combination and work your way diagonally to the left – on the subsequent line you'll find (3,5) then one down and across (4,4) and so on until you reach the last line.
This table is very important to your game play as being aware of the outcomes of the dice can assist you understanding the probability of achieving a particular total. So if you have the opportunity to obtain 5 combinations on the two dice that produce 8, you have a better chance when wagering on that number than the 2 possibilities for the four. Understanding this will enable you to maximise your wagers and improve your chances of wininng as far as possible.