Since today's slot machines are no longer mechanical, the slots odds are calculated by computers. The machines run on what is known as a "random number generator," which ensures that over several hundred thousand spins, each combination will come up a certain number of times. Each spin is independent of all others, but there is a statistical probability of each number coming out. The machine essentially is programmed to be just as random as earlier slots were, but the statistics are weighted to ensure that the machine remains profitable for the casino.
The machine doesn't have a program for each day, or even for a certain number of rolls. The casino has a statistical setup for each slot machine, and over the life of the machine, on average, the slots payout will end up being the percentage it has been set for. Casinos do not publicize the statistics on any specific slot machine. Some states in the United States have requirements for minimum payouts, and some states require casinos to present a record of their overall payout percentages. Some require specific odds for each denomination of machine and for progressive jackpots and straight slots.
Because many states require this information to be made public, the slots2000.com staff has found a lot of general trends. For example, higher denomination machines generally have a slightly better payout, because more money goes through the machine in the same amount of time. To make the same amount of money, the machine needs to hold a smaller percentage. Bigger casinos often have better payout percentages than smaller casinos, because the larger traffic generates more earnings. Progressive slots and slots with higher jackpots often have lower payouts. Online slots have better payouts because they have much lower overhead, and often have much more traffic than land-based casinos.
The slots odds are always against you, though. Remember that casinos make money because they set the odds. Sometimes you beat the odds, either by getting comps from land-based casinos, or by getting sign-up bonuses from online casinos. Sometimes you will have a lucky day, but remember that luck sometimes runs out, and even if you've won with a specific game or machine, you may lose the next time.
