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How Much Bankroll Is Enough?

29 October 2007

By John Robison

Hello, John,

Thank you for answering my question about slot machine odds. I seem to learn more from this forum than anywhere on the net because you aren't selling anything. I have another question about bankroll. How much is enough?

I know it's all about entertainment but I play to win. That is my intent at least. So I have noticed over the years that I rarely win with a small bankroll. Sometimes for fun I take 20 bucks and play quarters Double Diamond 1 credit per spin.

I rarely win though. Yet on the other hand I take 400 dollars and play quarters and dollar machines all on the same game type. When I do this I always win. Sometimes it takes a while, but I usually win about 40 dollars. It's when I continue to play eventually my bankroll diminishes.

To sum up my question: Can your bankroll and the machine type you play result in predictable outcomes on average? I refuse to believe it's all luck because of the way the machines are designed. Yes, they take your money but the also pay you a little back. I feel style of play can really influence a winning session because really who wins anything on penny slots?

How much bankroll is enough? Your bankroll should be large enough so that you don't run out of money before you run out of desire to play. What is that in dollars?

Let's say you want to play for two hours at 10 spins per minute. That's 1200 spins. If you're playing a quarter per spin at one credit per spin, your cost per spin is....

Well, it's not really a quarter because you will win money on some spins, but we don't know which ones or how much because the results of each spin are random. Your average cost per spin is really the house edge times 25 cents. But's that a long-term average, so we really can't use it for a session bankroll.

To be guaranteed of being able to play all 1200 spins, you need a bankroll of $300. If we knew the layouts of the virtual reels, we could calculate how much money you would need to have a given probability of being able to play 1200 spins.

We don't know how machines are programmed, though, so I use a rule of thumb for bankrolls. I like to have a large enough bankroll to fund 100 spins per session. That's usually enough to keep me playing for an hour or longer, but sometimes I've gone bust in 30 minutes or less. If you're playing a high hit frequency machine, you can get by with a lower bankroll. If you're playing a low hit frequency machine, you might want to up your bankroll to see you through the long dry spells that frequently occur on those machines.

There are two reasons you tend to do better with the larger bankroll. One, the larger bankroll funds more spins and you have more chances to hit something. The New York Lottery used to use this slogan: "You gotta be in it to win it." The same is true on the slots. Double Diamond machines don't have hit frequencies as high as other machines, so it's fairly common to have enough cold streaks to eat up a small bankroll like $20.

The second reason is that the more spins you play, the closer your results will tend to be to the machine's long-term payback. And that brings me to the answer to your last question.

There are no predictable outcomes on average based on bankroll and machine type. But given a particular machine, if you kept track of your results playing the machine, the payback you experience will tend to get closer to the machine's long-term payback the more you play. That's the only thing that's predictable on a slot machine.

Best of luck in and out of the casinos,

Send your slot and video poker questions to John Robison, Slot Expert, at Because of the volume of mail I receive, I regret that I can't reply to every question.

John Robison
John Robison is an expert on slot machines and how to play them. John is a slot and video poker columnist and has written for many of gaming’s leading publications. He holds a master's degree in computer science from the prestigious Stevens Institute of Technology.

You may hear John give his slot and video poker tips live on The Good Times Show, hosted by Rudi Schiffer and Mike Schiffer, which is broadcast from Memphis on KXIQ 1180AM Friday afternoon from from 2PM to 5PM Central Time. John is on the show from 4:30 to 5. You can listen to archives of the show on the web anytime.

Books by John Robison:

The Slot Expert's Guide to Playing Slots