Dice Probabilities
Sep. 11th, 2009 09:06 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
trickykittyYo Ho, Gamers.
On behalf of![[livejournal.com profile]](https://www.dreamwidth.org/img/external/lj-userinfo.gif)
mister_free, I created a simple spreadsheet (MSExcel 2003) that will calculate basic dice probabilities.
You enter the # of sides of the dice, the # of dice in the dice pool, and the target number for a success (i.e. 7+ on a D10). Then you go down a chart and find the number of success needed (say you need 3 successes out of 10 dice). Then scroll across and it tells you that you have xx% chance of making your goal. It gives all of the percentages from 1 to 20 dice simultaneously, so it's a nice tool that you can use to compare probabilities given a particular dice pool and target number.
It does not take into account adding bonuses, etc. It's very basic, but should be easy enough to tweak if you are familiar enough with Excel equations*.
If you would be interested in a copy of this drop me a line here with you email addy (comments screened) and I'll shoot you a copy.
You only have to fill in the three gray cells. The rest of the chart will calculate automatically.
This is obviously for a homogeneous pool of dice. They must all be of the same #-sided dice.
The variable names were for my reference and really have no play in anything on the spreadsheet. You can delete that row (Row 2) if you prefer and it will not affect the functionality of the spreadsheet.
The chart only goes up to a dice pool of 20 dice. If you want it to go farther, simply copy/paste/drag the equations in the chart down to the desired level**.
"Cumulative % chance" is the column you are wanting to pay attention to.
There is a column for "exact %", but for the most part this column is irrelevant. It translates to, "if you wanted 3 AND ONLY 3 success, then your % chance of reaching your goal is xx%". This is virtually useless since most GMs will accept 3+ successes, not just 3 and only 3. I had to calculate the exact number of successes in order to calculate the cumulative, so I figured for the sake of symmetry and to satisfy my OCD brain I would include it.
Along with the spreadsheet, there are also a bunch of tabs that I used to verify the accuracy and functionality of the main spreadsheet. Each tab is labeled by the sample dice pool (2 dice @ D10 = 2@10). Along the top row of each tab are the possible goals (1+ success @ target 7 = 1@7). Find the tab and column that matches what you are working with and scroll down. The bottom row is a tally of all the possible rolls that meet the goal requirements. This number should match the "cumulative" cell in the chart on the main spreadsheet. If it doesn't, then it means I made a mistake on the tab, seeing as how I created all of those by hand and at times was pretty dang tired while doing it. (I've already found 1 mistake on the 3@10 tab, but it's corrected now.)
Enjoy!
* I'm not going to teach you how to do things in Excel, so please don't ask.
** (See *) If you can't do this yourself I'd be happy to do it for you if you ask. Just tell me the max die pool size and I'll adjust it for you accordingly. I might do some other tweaking if asked, but I reserve the right to say no if I think it might be too complicated or something I just won't have the time for.
On behalf of
mister_free, I created a simple spreadsheet (MSExcel 2003) that will calculate basic dice probabilities.You enter the # of sides of the dice, the # of dice in the dice pool, and the target number for a success (i.e. 7+ on a D10). Then you go down a chart and find the number of success needed (say you need 3 successes out of 10 dice). Then scroll across and it tells you that you have xx% chance of making your goal. It gives all of the percentages from 1 to 20 dice simultaneously, so it's a nice tool that you can use to compare probabilities given a particular dice pool and target number.
It does not take into account adding bonuses, etc. It's very basic, but should be easy enough to tweak if you are familiar enough with Excel equations*.
If you would be interested in a copy of this drop me a line here with you email addy (comments screened) and I'll shoot you a copy.
You only have to fill in the three gray cells. The rest of the chart will calculate automatically.
This is obviously for a homogeneous pool of dice. They must all be of the same #-sided dice.
The variable names were for my reference and really have no play in anything on the spreadsheet. You can delete that row (Row 2) if you prefer and it will not affect the functionality of the spreadsheet.
The chart only goes up to a dice pool of 20 dice. If you want it to go farther, simply copy/paste/drag the equations in the chart down to the desired level**.
"Cumulative % chance" is the column you are wanting to pay attention to.
There is a column for "exact %", but for the most part this column is irrelevant. It translates to, "if you wanted 3 AND ONLY 3 success, then your % chance of reaching your goal is xx%". This is virtually useless since most GMs will accept 3+ successes, not just 3 and only 3. I had to calculate the exact number of successes in order to calculate the cumulative, so I figured for the sake of symmetry and to satisfy my OCD brain I would include it.
Along with the spreadsheet, there are also a bunch of tabs that I used to verify the accuracy and functionality of the main spreadsheet. Each tab is labeled by the sample dice pool (2 dice @ D10 = 2@10). Along the top row of each tab are the possible goals (1+ success @ target 7 = 1@7). Find the tab and column that matches what you are working with and scroll down. The bottom row is a tally of all the possible rolls that meet the goal requirements. This number should match the "cumulative" cell in the chart on the main spreadsheet. If it doesn't, then it means I made a mistake on the tab, seeing as how I created all of those by hand and at times was pretty dang tired while doing it. (I've already found 1 mistake on the 3@10 tab, but it's corrected now.)
Enjoy!
* I'm not going to teach you how to do things in Excel, so please don't ask.
** (See *) If you can't do this yourself I'd be happy to do it for you if you ask. Just tell me the max die pool size and I'll adjust it for you accordingly. I might do some other tweaking if asked, but I reserve the right to say no if I think it might be too complicated or something I just won't have the time for.
