Pokies and Slot Machine Information

Basic slot machine math

May 3, 2008 on 11:56 am | In Slot machine overviews | No Comments

It’s time to clear up a basic mis-understanding about playing slot machine games. People often hear about the percentage payout rates of particular slot games and don’t really understand how they work.

A fundamental aspect of slot machine games is that there is a precisely defined house ‘edge’. The games are designed to provide a guaranteed winning margin to the venue over time. The amount of the margin depends on the game, the venue and whether the machine is linked to a progressive or other jackpot system.

The game margin is expressed as a percentage. If a game has a payout rate of 90.50% for example, it means that 9.5 cents of every dollar per spin you play, on average, will be lost.

The payout rates vary quite substantially. In Australia casinos generally have the highest payout rates - 90% or more. Pubs and clubs may have the lowest - as low as 85% in some areas. Bear in mind that the game may look identical in either venue, but you’ll lose as much as 50% more quickly playing in a pub than a casino. Unfortunately there is no way of telling what payout rate a machine has been set at.

Progressive jackpot games will often pay out less than other games. A percentage of every bet - say 4 cents in every dollar you invest - is being put towards the jackpot amounts. Unless you win a jackpot your overall payout rate on a progressive machine is going to be less than any other machine you might play. In other words, you might lose more quickly playing a linked jackpot machine.

None of the above considers the impact of doubling up. In many jurisdictions doubling a win using the standard red/black doubleup has no house edge - it’s perfectly even odds. If you’re a lucky person you can actually win quite large amounts using double up - as we’ve personally experienced.

A final aspect of payout rates to consider is their cumulative impact. A common misconception is that the percentage payback applies per session. For example - that if you take $100 to a casino for a night of fun on the pokies, that you’ll have $90 left by the end of the night if you play a machine with a 90% payout rate. The payout rate actually applies per spin over time.

Lets show some examples:

Starting Amount	Payout Rate	Bet per spin	Spins played	Time before funds run out
$10	90.00%	40 cents	256 spins	17 minutes
$20	85.00%	40 cents	340 spins	23 minutes
$50	85.00%	$1.00	340 spins	23 minutes
$100	90.00%	$1.00	1,006 spins	1 hour, 7 minutes
$100	85.00%	$5.00	140 spins	10 minutes
$500	82.00% *Linked jackpot machine	$10.00	284 spins	19 minutes

Times may be rounded up to nearest minute. Assumes 4 seconds per spin. All
figures are highly theoretical and are not to be considered mathematically
perfect.

The best advice remains to budget your gaming - take a pre-set amount and be prepared to lose it! Increasing your bets will generally only make your wallet empty more quickly (though it may also increase your likelihood of winning a progressive jackpot).