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Slot Machine Odds

Slot Machine Odds
by Jason Green of

The first slot machines were mechanical devices and the odds of the machine were determined by the number of reels, as well as on the number of symbols that were on each reel. The selection principal was new every time the reel was spun.

For example, the Liberty Bell slot machine had 3 reels each reel having 10 symbols and each of the symbols on the reel had the same probability of being shown on the payline. The chance that a symbol appearing on the reel on the payline was 1 in 10. Because of this the odds of hitting the jackpot on this game was 1,000 to 1, as 10x10x10 = 1,000, which are the possible combinations.

Nowadays slot machines are computer generated, as now the reels do not have any independent action. The Random Number Generator (RNG) and the computer coordinate them in order to come up with a payback percentage.


The primary thing that you need to be aware of, in terms of slots odds, is that every single spin is not related to the previous spin or the next one. Each time you push the button or pull the lever, a new random number will be generated by the RNG. This will only determine the outcome of the spin. Because of this slot machine cycles and hot and cold slot machines are only myths, as they do not exist with new computer generated slot machines.

Another important thing you should remember is that in slot machines of today, from 3 reel, video slots, or Internet slots, not every combination on the payoff table will have the exact same chance of hitting, as it will be determined by the computer chip for the game. The lower amount of wins will hit more times than the jackpot in order to come up with a certain payback percentage. Therefore, while it is the case that each and every spin is random every combination will not be equal.

It is also a myth that a casino can “tighten up” a slot machine. The odds for a slot machine are ingrained in the program and the slot machine’s computer chip. Generally, the casino will not be able to alter the odds on the machine without replacing it.

Usually payback percentages have to be, by law, set at a certain level. Generally that level, these days, is between 85% and 100%. This will depend on the game played, the location (jurisdiction), and the average house advantage, which is usually calculated to be around 9%. Basically this means that in the long run a slot machine will pay out around 91 cents of every dollar and casino makes 9 cents that is played on the machine.

Obviously players would not play the game of slots if each and every time they played a dollar they only received 91 cents back. However, a slot machine is programmed to return high payouts, when the right combination hits, and because of this it is a volatile game and a lot of fun. The great thing is with slots is that you have the same chance to hit the jackpot each and every time you pull the lever or push the button.

It is almost impossible to find another game in a casino that has such a big house edge. However, the game of slots is immensely popular and account for around 70% of all casino game revenue.

The big house edge will make it less likely that you hit the jackpot, but if you do the payout will be significant.

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