True Odds are the actual probability for an event to happen. This can be expressed in three practical ways: The number of successful results in the total number of results (X in Y), or the number of successful results to the unsuccessful results (Z to X) or a percentage. Here are a few examples:
- Craps: A 7 is the most likely result on the Craps table. The odds of it happening are 1 in 6, or 5 to 1, or 16.6667%
- Roulette: Any single number on the layout is equally likely. The odds are 1 in 38, or 37 to 1, or 2.6316%
- Slots: We'll use a hypothetical jackpot here. The odds are 1 in 5000, or 4999 to 1, or 0.02%
All of the possible results for a given event, when expressed as a
percentage, will add up to 100%. The difference between the True Odds and the
Table Odds is how you determine the
House Edge.
Let's break down all of the possibilities on the Craps table for practice. There are 36 different possible combinations on the dice, for 11 different possible outcomes.
2. 1 in 36 chance, 35 to 1, 2.7778%
3. 2 in 36 chance, 17 to 1, 5.5556%
4. 3 in 36 chance, 11 to 1, 8.3333%
5. 4 in 36 chance, 8 to 1, 11.1111%
6. 5 in 36 chance, 31 to 5, 13.8889%
7. 6 in 36 chance, 5 to 1, 16.6667%
8. 5 in 36 chance, 31 to 5, 13.8889%
9. 4 in 36 chance, 8 to 1, 11.1111%
10. 3 in 36 chance, 11 to 1, 8.3333%
11. 2 in 36 chance, 17 to 1, 5.5556%
12. 1 in 36 chance, 35 to 1, 2.7778%
Add them all up, and you get 36 out of 36, or 100% (Note: Due to the rounding of infinite strings to the fourth decimal place, the percentages listed here do not add up to exactly 100%, but the true numbers do).