Appendix A

Dice Conversions

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Percentages are Universal

Anytime you use dice in a RPG, you’re really playing with probabilities and chance. Probability and chance are measured as percentages. By keeping this system to straight percentile rolls most of the way through, it keeps it as pure to probability as possible. However, suppose you don’t like the idea of using 2d10s, percentile dice, or a d100? What do you do then? Luckily, because everything is in percentile anyways, it’s easy to just convert all the percentages to other numbers if you want to use different kinds of dice. Presented here is a sort of master dice list that lists the percentage chance of rolling various numbers on different dice. Note that this section gets kind of heady with percentages, so it’s not for the weak of INT. Hell, if you’re up for it, you may even want to double check my numbers!

How to use the tables

A lot of this depends on how you use the dice, is a natural 20 the end-all be-all best that you can roll on a dice, or is a natural 1 the best you can roll? Do you have to roll equal to and above a target number or just above the target number? To convert a % from this system to another dice type, get the % you want to convert, round up or down, and find where it is on the probability tables below based on how you roll the dice.

Example: You want to convert 60% chance of doing something into a d20 roll, lets say that a natural 20 is good for us and you have to roll Above the target number. Looking below you find that the target number for 60% Above is an 8. That means that you have to roll above an 8 in order to succeed.

Also, if you want to determine how much a bonus is worth, you simply divide the percentage of the bonus by the Base percentage listed and then round down or up (depending on what the intervals are).

Example: You want to convert a +20% bonus to your Strike mod. Assuming the same conditions as above apply (Nat20 = good), dividing 20% by 5% equals +4. On a d20 you would get a +4 to your Strike mod.

You can also use these tables in reverse and figure out what percentage chance you have of rolling for a target number.

Example: On a d20, you need to roll Equal to or Above a 15 to succeed on a roll. Consulting the table, you find that you have a 30% chance of making that roll. Good luck!

d20

Base: 5%

Natural 1 = Good Natural 20 = Good
Below Equal to or Below Equal to or Above Above
1 1 5% 1 100% 1 95%
2 5% 2 10% 2 95% 2 90%
3 10% 3 15% 3 90% 3 85%
4 15% 4 20% 4 85% 4 80%
5 20% 5 25% 5 80% 5 75%
6 25% 6 30% 6 75% 6 70%
7 30% 7 35% 7 70% 7 65%
8 35% 8 40% 8 65% 8 60%
9 40% 9 45% 9 60% 9 55%
10 45% 10 50% 10 55% 10 50%
11 50% 11 55% 11 50% 11 45%
12 55% 12 60% 12 45% 12 40%
13 60% 13 65% 13 40% 13 35%
14 65% 14 70% 14 35% 14 30%
15 70% 15 75% 15 30% 15 25%
16 75% 16 80% 16 25% 16 20%
17 80% 17 85% 17 20% 17 15%
18 85% 18 90% 18 15% 18 10%
19 90% 19 95% 19 10% 19 5%
20 95% 20 100% 20 5% 20

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Appendix A

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