Concerning Risk Of Ruin of 5%

I'm hoping someone can help me out. I'm trying to find out what size bankroll I will need in order to play with a 5% risk of ruin. I'm not sure how to do it or I'd do it myself.
I play a 6 deck shoe and the casino cuts out one deck-sometimes a deck and a half. Rules are DAS, DA2, LS. As I understand it playing with a 5% ror means I have a 5% risk of losing all my money and a 95% chance of doubling my bankroll before that occurs. I play $5.00 and increase my bets to $15.00-$25.00-$40.00 and $50.00. So I'm using a 1-10 spread using Renzeys' Kiss III count. I'm thinking I'll need a bankroll of $5,000. Thank you one and all!

"I'm hoping someone can help me out. I'm trying to find out what size bankroll I will need in order to play with a 5% risk of ruin. I'm not sure how to do it or I'd do it myself."

Simulation! CVCX or BJRM 2002.

"I play a 6 deck shoe and the casino cuts out one deck-sometimes a deck and a half. Rules are DAS, DA2, LS. As I understand it playing with a 5% ror means I have a 5% risk of losing all my money and a 95% chance of doubling my bankroll before that occurs."

No, it means 5% of losing the bank and 95% chance of making all the money in the world. The ruin formulas we typically use have nothing to do with doubling your bank.

"I play $5.00 and increase my bets to $15.00-$25.00-$40.00 and $50.00. So I'm using a 1-10 spread using Renzey's Kiss III count. I'm thinking I'll need a bankroll of $5,000. Thank you one and all!"

Sounds very close to me. Another $500-$700 would probably be better.

Don

Don-
Thanks alot! (I feel like I just got batting instructions from Babe Ruth-know what I mean?)

Don , I remember reading somewhere (Uston?) that RoR included the chance of doubling your bank before losing your bank. Seems others also operate with that definition, so I don't think I'm crazy. Wher did the doubling idea come from?

"Don, I remember reading somewhere (Uston?) that RoR included the chance of doubling your bank before losing your bank. Seems others also operate with that definition, so I don't think I'm crazy. Where did the doubling idea come from?"

There ARE ruin formulas that are expressed in that fashion. They just aren't that way in BJA3 or in any of Norm's online calculators. In addition, that ISN'T the convention that most of us use when we talk about RoR. We have a bank, and we want to know what the chance is that we might lose it all. Our goal isn't to double that bank; rather, it is to win all the money in the world! :-)

Is there something special about stopping once you double your bank? If so, I'm not sure what the attraction is.

Don

Most people want to have a goal. Winning all the money in the world is fun to think about but not attainable. Doubling a bank is a realistic goal for any player(s) or team. It just gives a place to stop and plan again. Winning forever is obtainable with a winning strategy but when do you stop? I think having a goal in mind (like doubling a bank) is a good plan and something to look forward to. The older ROR goals were placed for that reason. Now advanced thinking surpasses that but most have difficulty comprehending that. Nice to see you explain it as it actually is.

Thanks Don! Every now and then on these and other boards the definition of RoR comes up and I'm surprised by the number of folks that differ on that definition. At least I have myself reset.

"Most people want to have a goal. Winning all the money in the world is fun to think about but not attainable. Doubling a bank is a realistic goal for any player(s) or team. It just gives a place to stop and plan again. Winning forever is obtainable with a winning strategy but when do you stop? I think having a goal in mind (like doubling a bank) is a good plan and something to look forward to. The older ROR goals were placed for that reason. Now advanced thinking surpasses that but most have difficulty comprehending that. Nice to see you explain it as it actually is."

I don't disagree with anything you've written. So, players have a choice: with Norm's online calculators, you can specify ROR with no goal, or ROR with a goal. The nice thing about the latter is that there's no requirement for the bank to double. The goal can be anything that makes you happy. You may also specify a time constraint, or none at all. We have the formulas.

http://www.card-counting.com/blackjack-calculators.htm

Don

If you play with a fairly decent bank, such that ROR is rather low (say, < 10%) to begin with, the difference between ROR before doubling and ROR with no goal is actually very slight.

And it's easy to understand why. The only difference between the two would be when you would double your bank, not stop, and then STILL be ruined, now losing back twice your starting bank.

Isn't going to happen very often!

Don

I'm going to be treating my blackjack play as fun/part time business. If my EV is say $20.00 an hour that's o.k. for now-as my bankroll increases so will my bets and my EV. I was recently talking to a friend who is working on his doctorate-he claims there are a great many college graduates "out there" today who are working for minimum wage-which I think is $8-$9 per hour depending on which state you live in. I have a full time well paid profession but $20.00 an hour m.i.f.-(money in fist) received having fun isn't bad for the moment. Good cards!

ROR calcs assume that you don't withdraw any amounts from your bankroll. If you treat the game as a part time business, and withdraw your full EV, or worse yet, all of your actual winnings, then your ROR will be much higher.

Cougfan-
Thank you for that heads up-I was unaware of that. I really appreciate the info!

There's an analysis on Green Chip by Math Prof on the impact of taking a percentage of your winnings instead of adding them all to your bank. Essentially you are reducing your EV (from the perspective of bank growth) which increases your Risk of Ruin.

Once a bank is doubled or a goal is reached then it's a good idea to resize. This gives allowance to take some profits. If a team does this then a percentage of the winnings can be volunteered back in the form of investment creating a new bigger bank. Solo players can do the same. What's the sense of making endless money from your investment without taking some profits? Investment firms do it all the time. I say be kind and reward thyself for the hideousness that 21 players have to go through!

Since you have a good day job, one alternative is just to view your BJ BR as a sort of retirement fund. Continue to make contributions as you can, while you also re-invest all of your winnings. You can gradually increase your playing stakes as your BR increases. Your skill will also increase at the same time. You can cash it out when your playing days are over.

You may also want to decide ahead of time on a BR level where you will re-size your bet levels and recalculate ROR. Alot of players resize if they double their BR, or it drops in half, for example.

Also, assuming that you don't "need" your BR money for living, given your day job, you could just go for maximum BR growth, which means betting at full Kelly, and constantly re-sizing your bets. Realistically, you might bet 2/3 or 3/4 Kelly and only re-size before each BJ trip. In theory, it's impossible to go "broke" using a pure Kelly betting scheme, since you are constantly resizing your bets.

Lastly, you also need to consider the psychological aspect of your bet amounts. Keep in mind that it is possible to lose 8 1/2 times the amount that you put in the betting circle. Extremely unlikely, but definitely possible. This means that if you have a max bet of say $100, you need to be mentally prepared to lose $850 on ONE hand. The last thing you want is to be in a situation where you cannot bring yourself to double that 3rd or 4th split hand that is sitting in front of you.

Buy BJA 3 and read it. Then read it again every few months as you gain experience.