Are Slot Machine Payouts Random?

SLOT GUIDES / Sep 5, 2018
Are Slot Machine Payouts Random?

Katie Thompson

Sep 5, 2018 2 min read
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It’s one of the oldest questions in the gambler’s book: are slot machine payouts really random? Supposedly, as the saying goes, “the house always wins” but in reality, there’s a lot more to it than that.

The randomness of a slot machine, whether online or in a land-based casino, is based on a mix of science and very technical computing.

What makes slot machine payouts random?

Slot machines use a technology called a random number generator, or RNG. In days of yore, this random number generator would have existed, but it would not have been computer generated.

Random number generators are used in many gambling games – even a roulette wheel or the roll of a dice can be classed as a random number generator.

How do random number generators work?

The difference with modern random number generators is that they come in two forms – the hardware random number generator and the pseudorandom number generator. The former is less sophisticated and relies on an external device which generates random numbers using compound values as a starting point.

An algorithm generates results based on a rule or action, for example, spinning a slot. Technically speaking, this is not 100% random as it relies on an external output, which is why online slot machines prefer the pseudorandom number generator.

The pseudorandom number generator relies on ‘seed numbers’ instead, which are produced every millisecond. These are produced by taking the last one or two numbers and adding, subtracting, multiplying or dividing them to get an outcome.

This gives us thousands of constant calculations. They use algorithms, too, but can generate thousands of results at any one time.

Are the slots in my favour?

Naturally, in order for the gambling business to be profitable, there needs to be some degree of a house edge. This is true of slots – every bet made offers a payout that is less than the actual odds of winning.

That said, there are also many myths surrounding slot machines– for example, though it may feel like slots get ‘hot’ or ‘cold’, you’re no more likely to win if you’ve been playing for 10 minutes than if you have for 10 hours.

Other factors that may affect your chances of winning

Games such as roulette have a pretty clear-cut outcome – a 1 in 37 chance. For slots, it’s a little more complicated.

For example, the number of reels on a slot can vary, which in turn affects the chance of certain symbols lining up with one another.

The random number generator is what determines this, and in most cases, the less likely the two symbols are to appear in line with each other (for example, two bonus symbols), the higher the payout.

The ‘stops’ on a reel are now determined by these generators, so nowadays the odds of a certain symbol appearing every few spins are smaller. This is a lot fairer, and it’s reassuring to know that slot payouts are in fact, random!


Katie Thompson

Katie Thompson is an NCTJ-trained journalist and freelance online gaming writer. She enjoys researching the iGaming industry and writing comprehensive guides on the history of gambling, beating t ...