Five Advantages of Pass-Fail Dice Pools

In the nearly half a century since Dungeons and Dragons first emerged from the primal war-gaming soup, game designers have gifted us with a plethora of different core dice mechanics. Most of them can be separated into two broad categories: static dice and dice pools. In static systems, players roll the same number of dice for each roll. This includes the ubiquitous d20 and the 2d6 of Apocalypse World. Meanwhile, dice pools have a variable number of dice, with the total number usually determined by the statistics being rolled. Players build a “pool” of dice based on their characters’ abilities.

Within dice pools, there are two further categories. In additive dice pools, players roll their dice, then add each die together for the total. I call the second category pass-fail dice pools,* and this is what we’re talking about today. In pass-fail pools, each die must come up a certain number or higher to be considered a pass, and PCs need a certain number of passes to succeed on a roll. Burning Wheel is a common example: PCs roll a number of d6 equal to their skill,* and each die that comes up a four or higher is a pass.

The pass-fail dice pool is my favorite type of core dice mechanic by a country mile. I think it’s the best option on the market, but I don’t expect you to just take my word for it. Let’s look at five advantages it brings to the table that put it above the competition.

1. Leveling Up Is Tactile

Everyone loves leveling up. There’s a very real satisfaction in seeing your character’s numbers increase and knowing that from now on you’ll be more capable than you were before. But in static-die systems, those new bonuses are only on paper. Sure, you get +5 with your axe now instead of +4, but the basic action of attacking is the same.

With dice pools, you feel your character leveling up in your hands. Instead of an abstract +1, you add an extra die to your pool. Playing a high-level character actually feels different than playing a low-level character. And when it comes time to roll the dice, you get the satisfaction of seeing your new bonus in action.

Leveling up isn’t the only way to feel your character’s capability changing. Tenra Bansho Zero gives PCs more and more dice as they go through anime-style power-up scenes or when they get wounded – heroes fight harder when they’ve been hurt! Rolling handfuls of dice immerses players in the game’s extreme action sequences, letting them feel like gods among mortals.

Some systems take this tactile advantage even further. Anima Prime has you move dice from one pool to another as the main component of combat. This creates important choices. Is it more important to have dice in your attack pool, or do you want to save some to power for your special abilities? While this could be replicated with numbers on paper, it won’t be nearly as satisfying.

2. Less Math Is Required

It’s time for you to attack your archnemesis. You take up your d20, add in your strength bonus, your base-attack bonus, your magic-weapon bonus, your terrain bonus, your dance-party bonus… Okay, I made one of those up, but you get the point. Many static systems require a lot of math before each roll. Additive dice pools are even worse. They ask you to add up a handful of dice after you’ve rolled, slowing down the game when you just want to know what happened.

With pass-fail pools, these problems will plague you no more. First, you don’t have to add up anything after the roll. Just count the number of dice that are over the pass threshold to see if it’s enough. Easy. And while it’s certainly possible for a pass-fail pool to have as many miscellaneous bonuses as a static system, they’re easier to add up. Instead of keeping the numbers in your head or marking them on paper, you put dice in your hand as you count. The physical reminder makes it much easier to keep everything straight. Once you roll, you don’t have to add the result to the number on your sheet; it’s right there for you to count.

Reducing dice math may not seem like much. For veteran players, it becomes second nature to add up all the damage of a fireball or the numerous bonuses for a diplomacy check. But even routine math can slow the game down, and an important roll is the worst time for that. Rolling the dice should be a moment of suspenseful excitement as you wait to see if your plans bear fruit, not a long pause in the game as you crunch numbers.

For new players, the benefit is even more pronounced. If you’re just joining the hobby, the math can be a major hurdle. Pass-fail pools reduce that burden and let you focus on learning the game.

3. Probability Is Easily Adjusted

For some groups, especially those that have been into roleplaying games for a long time, altering the probability curve for standard rolls can be a breath of fresh air. It changes how the game is played and opens new possibilities. Fortunately, pass-fail pools have the potential for such changes, if you want them.

Every system with a pass-fail pool has at least four sliders that can adjust the odds of success or failure on a roll. The first two are changing the number of passes needed for success and changing the number of dice a player rolls. Harder tasks mean more passes are needed, while dice bonuses and penalties are usually handed out based on a PC’s condition. If the character has an exceptionally sharp sword, that could be a bonus die. If the character is wounded, that could take away one die.

Many groups only need those two sliders, which is fine. But if you want to get creative, there are two others in easy reach. The third slider is the number each die needs to roll in order to be considered a pass. Changing that number has an unusual effect on the roll: it alters the odds of a successful roll but not the possible number of passes or fails a player could get.

Let’s say you’re rolling five d10s, and normally each die needs to be a six or up to be a pass. If that threshold is changed to five, then the odds of getting passes goes up, but the maximum number of passes is still five. If the threshold is raised to seven, it has the inverse effect. The odds of passes go down, but the maximum number is still five. This can be useful in situations where something makes a PC’s task easier or harder, but it doesn’t change their absolute potential. World of Darkness often uses it for magical effects, while Burning Wheel employs it for divine assistance.

Finally, the fourth slider is what number each die has to roll in order to “explode.” That’s a term meaning that you get to keep the original die, plus roll another one in addition to it. In most systems, this is the highest value on each die. Ten for d10s, six for d6s, etc. But there’s no reason it has to be those numbers. Lowering the explosion threshold makes for much more chaotic rolls, as the likelihood of chain explosions goes up. It’s not a great fit for every game, but if you want characters to have sudden bursts of ability, this slider is for you.

4. Randomness Is Kept in Check

Many static systems have an issue with too much randomness. Consider D&D. A character with 18 Strength is supposed to be at the peak of human ability, gaining +4 to strength-related roles. A character with 10 Strength is at the low end of average — the kind of strength you get from writing blog posts all day. It gives +0. In a contest of strength, both characters would roll 1d20 and add their bonus, giving the noodle-armed blogger a decent chance of besting the chiseled Adonis.

The same problem is rife across all kinds of rolls in D&D and other systems. When bonuses are too small, especially common at lower levels, the random dice roll has an oversized influence on success or failure. It feels like your character’s ability isn’t important, only subject to the fickle hand of fate.

Dice pools, pass-fail or otherwise, address this problem handily. Instead of adding your bonuses to a random roll, your character’s ability determines what the random roll will be. In a system like Burning Wheel, a character with 3 Power* would roll 3d6, while a character with 6 Power would roll 6d6. The chances of the champion weightlifter being bested by an office clerk feel more in line with reality under this model.

Another issue with randomness in static systems is the likeliness of fluke rolls. With a single die, be it d20 or otherwise, a minimum roll is as likely as a maximum roll. Even if your system doesn’t have rules for critical failure and success, that still means characters are just as likely to have a perfect moment or an absolute disaster as they are to get average results. That doesn’t match our understanding of how the world works, so it creates dissonance at the table. Some static systems use multiple dice, but that doesn’t usually solve the problem. Iron Kingdoms’ 2d6 is better than a single d20, but maximum and minimum rolls are still more heavily weighted than they should be.

Dice pools solve this problem by creating a bell curve. As you add more dice, an average roll becomes more and more likely, with maximum and minimum rolls becoming the least likely. When an uncommonly good or bad roll does happen in a dice-pool system, it feels like a special event and not part of a choppy reality simulator.

5. The Dice Always Matter

When a static system has random dice rolls that overshadow character ability, the most obvious solution is to increase character ability bonuses. This does help, but setting bonuses becomes a narrow balancing act. You see, if the ability bonuses get too high, it’s the dice that don’t matter. This is common in d20 systems, where bonuses can reach truly staggering levels, but it also happens in systems like Fate. In Fate, the bonuses gained from spending the system’s meta currency are far more valuable than anything the static dice can roll.

Rolling dice is a huge part of the enjoyment in playing RPGs. When the dice no longer matter, it’s just sad. There’s no excitement about the outcome of PC actions because those outcomes are never in doubt. When PCs have enough bonuses to always succeed, then there’s no satisfaction in victory. Worse, the dynamic can occasionally swing in the opposite direction, with difficulties so high that even good rolls can’t overcome them. That creates a sense of hopelessness.

It’s difficult to solve this problem in static systems, because bonuses need to start high enough that they matter in the rolls, but they don’t ever go high enough for the dice to stop mattering. If a static system has this careful balance at character creation, then dice will probably be unimportant to higher-level characters. On the other hand, if a system is balanced for higher-level play, then low-level characters will have measly bonuses.

Dice pools solve this problem the same way they keep randomness in check: bonuses aren’t in addition to the dice; bonuses give more dice. When a PC levels up in a dice-pool game, they don’t add a higher bonus to their roll; they add more dice. This difference may seem arbitrary from a statistical standpoint, but it’s very important. Rolling dice is fun. In a dice-pool system, what you roll is always important.

With all the advantages dice pools offer, they are well worth the cost of picking up a few extra d6s or d10s at the game store. This is especially true of pass-fail systems, which eliminate many of the dice pool’s downsides. Even if dice pools aren’t your favorite type of core mechanic, I hope you have a better understanding of the advantages they bring to the table.

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  1. Reiksson

    My only major critique of dice pools is when games have the ability to reach dice amounts in double digits with ease. It makes roll resolution take too long. Exalted and Shadowrun both have a big problem with this.

    • Alverant

      True, but if you’re playing in something like Roll20 you can order the dice numerically so you just have to count the ones that are 4 or higher. Or if you want to get more complicated I bet you can program a macro to count the number of successes for you.

    • Oren Ashkenazi

      Something like Roll20 can certainly make certain kinds of math easier, but in general I don’t take it into account since most RPGs are still designed to be played in person with physical dice. I do think it’s worth noting though that while it’s always possible for bonuses to get out of hand, I’d still rather be counting too many dice in a pass-fail dice pool than adding a million +1 bonuses in a static system.

      • William King

        Sounds like Mythic D6 is the system for you.

  2. Val Gunn

    Could you do this with a d20 pool, or is it just too swingy?

    How many dice are too many dice?
    To me, it seems throwing more than five or six gets annoying.

    • Oren Ashkenazi

      There’s no hard reason you couldn’t do a d20 dice pool system, the main reason I think most people don’t is that it doesn’t really provide much of a benefit, and d20s tend to keep rolling for longer than most other dice, which can make collecting them a pain in the ass.

      The cut off of too many dice is also gonna vary from person to person, but for me I think 5 or 6 for most rolls is reasonable, with spikes for more important rolls.

      • Val Gunn

        Thanks for the response!

        What I want is a d20 roll over system that caps at 20. In D&D you have Dis|Advantage where you roll 2d20 and keep the highest or lowest result. L5R & 7th Sea uses a roll & keep, but this isn’t quite what I want.

        You’re ability score is the number of dice you roll. If you have an advantage add another die. Disadvantage takes away a die. Roll and keep highest the highest single die. No math involved other than the amount of dice you throw.

        Is there any system that does this—I’d even look at ones using a different die type, as long as it’s roll & keep the highest one.


        • Michael Campbell

          Build your own.
          Replace the difficulty levels in the D6 system with lower values but require only the best one die.
          Very Easy 5
          Easy 10
          Moderate 15
          Difficult 20
          Very Difficult 25
          Heroic 30

          Very Easy 2
          Easy 3
          Moderate 4
          Difficult 5
          Very Difficult 6
          Heroic 8
          Legendary 10

          You could use open ending die on results of six to create the chance of a high result.

          Here’s a link to the D6 system.

        • El Suscriptor Justiciero

          That reminds me of the Silhouette system from Heavy Gear, although it is not exactly what you ask.
          You have two kinds of trait: “Skills”, usually no higher than 2-3, and “Attributes” which usually range from -1 to +2. When you make a check you roll as many d6 as your value in the Skill involved, take the highest die and add your relevant Attribute, then compare the final result with the check’s difficulty or “Threshold” (normally a value between 3-6); rolling higher than the threshold is a success, lower is a failure, and the result of a tie depends on what you are doing (e.g. in combat ties tend to go to the defender).

          There are a few things more; some subsystems care about the difference between your result and the Threshold, AKA “Margin of Success”/”Failure” (e.g. combat damage multiplies the margin by the weapon’s damage value), and rolling multiple 6s in one roll gives you a bonus.

          Overall it’s an interesting mechanic, although not without its hiccups.

      • Oren Ashkenazi

        That’s also doable, but one issue you’ll run into with a system where you roll multiple dice and only keep the highest one is a flat probability curve.

        No matter how many dice a player has, their maximum roll will never go up, but their odds of hitting that maximum roll will increase the more dice you add. This will do some weird things with probability.

    • Alverant

      One alternative is to assume X out of Y dice are a success and roll the remainder if it gets too much. For example you have a dice pool of 15d6 and it’s Shadowrun so you need a 5 or 6 to pass (1/3 of the possible results). So out of every three dice you get one success, on average. You could take your five successes and skip the dice rolling, roll three dice and assume four successes and so on. If the dice pool isn’t divisible by three, roll those extra dice as well.

      Sometimes the dice are in your favor, sometimes they aren’t so you’re trading in a sure thing for a lucky roll.

  3. Adam

    Mouse Guard uses this dice pool system, doesn’t it?

    Yet another reason why my group needs to start a Mouse Guard campaign.

  4. Chakat Firepaw

    There are two other kinds of dice pools:

    First is the “high roll” pool, where you roll the dice and just take the highest number. Examples are Ironclaw, (which also uses variable dice size, so a swordmaster might be attacking rolling 2d12 2d10 d6 while the untrained fat cook might have a single d4 to avoid this attack), and Silhouette, (in a slightly modified form, you roll xd6 and get +1 for each extra 6).

    Second is the “dice comparison” pool, where two pools make an opposed roll and compare die against die in descending order. The ur-example of this is the boardgame Risk, but the aforementioned Ironclaw uses it for damage rolls.

  5. Leon

    Cool post Oren,
    There’s a dice pool system I want to use for an almost free-form role playing game; but I cant find any similar existing systems that may indicate if it could work.
    6 = admirable success (+1 toward success).
    1 = infamous success (+1 towad sucxess, +1 damage).
    So basically, in many situations you don’t want to kill the enemy if you dont have to; you want prisoners to give you information, enemy wounded to keep the rest of the enemy occupied, or a hostage to grant you safe passage through hostile lands (or to get his family to pay out if your doing the chivalry thing).
    The idea is to make winning without killing difficult. I think this could work for social encounters too; do you pursuade with charm or threat. In a bar fight do you out class the other fighter or kick him in the balls etc. I think you could get some interesting interactions happening when characters are forced to do something reprehensable.
    So. I’m sorry that was a bit long; have you played anything similar to this, that would indicate if i should or shouldn’t subject my friends and family too it?

    P.s. the idea came about because chinese style dice are cheap where i live, we would use the red numbers 1’s and 4’s, easy to parse and fast to play.

  6. Leon

    ? for Jedi, infsmous = dark side.

    • Leon

      : [ the emoticon came out wrong.

      • Leon

        I just realised that with standard western dice you could assign any result; admirable success, infamous success or failure to any numbers you want.
        Yay, sleep depravation and caffine!

  7. Nikholas Stephanou

    hey, there is this particular type of dice mechanic I’m flerting with…
    You have a dice pool based on your skill, attributes, whatever. You roll the dice and only look for the highest result. Any repeated highest result adds +1 (so let’s say you roll one 12 as your highest result and another repeated 12, you have 13). Standart tests use TN (if you have a die that goes equal or over the TN, you succed), opposed tests well.. are opposed hehe but if it is a tie you look for the second highest result and so on (if there are no results left, it counts as a 0). I think this works best if you limit you dice pool to one number bellow the max natural die result of the die type you choose (I think d12 are the best with this system cause they allow a considerable variability of dices in the die pool — 1 to 11 — to account for different skill levels but not so many dices that it becomes kinda silly and not practical)

    any thoughts about it?

    • Chakat Firepaw

      (Points up)

      It’s basically a slightly modified Silhouette system with a tiebreaker on opposed rolls. Sil. didn’t need that because it used the margin of success rather than simply pass/fail, (MoS 0 meant things like “you managed a glancing blow that did no damage”).

      • Nikholas Stephanou

        hey, thanks for the recommendation (I never played Silhouette before, I’ll look it up)

    • Oren Ashkenazi

      So, my instincts are firmly against dice pools where you roll a bunch of dice and keep only the highest because the math gets really weird as you add more dice. The maximum potential never goes up, but the likelihood of rolling the maximum potential does, so as you get more dice, the probability flattens out and it because harder and harder to challenge a character.

      That said, lots of games use this kind of system, so it’s not unprecedented.

      • Nikholas Stephanou

        thanks for the reply
        I think there are two fundamental parts in making this system work: limiting the maximum number of dice (which beyong 10 dices I think it is ALMOST always a good thing to limit) so the probability doesn’t flat out THAT much and the +1 mechanic for repeated results, that allows high leveled characters to have results that go beyond the natural max of the dice and, in turn, allows GMs to put players in very challenging situations (lets say you have a 9d12 — the max in the system I’m thinking about. I can give you a TN of 16. that’s VERY challenging and very unlikely but not at all impossible)
        of course there are other tweaks I’m thinking about, this is just the most basic core mechanics

      • Michael Campbell

        You might also want to make each roll of 1 on the D12 cancel out 1D3 of your success.
        That way things don’t get boring even when a guy throws 24D12.

        Or alternately have special D12, say the red one.
        If it rolls a 1 then you automatically fail no mater how many success your rolled.
        If you’re throwing 12D12, your chance of getting at least one result of “12” is 1 – (11^12 / 12^12).
        Or 64.8% so setting 12 as “Nearly Impossible” difficulty is not actually the case when the other guy throws super human numbers of die.

  8. Slipstream

    I’ve been struggling to choose a dice mechanic for my RPG, after reading this I’m going with d6 dice pools all the way… Are there any arguments mixing in a distinct dice or two for random events?
    What do you think of that Jedi dice pool idea that Leon mentioned? Could be interesting.

    • Oren Ashkenazi

      There’s no reason you can’t include special dice to make the results more varied, but in general I recommend keeping the core dice mechanic as simple as it can be. If you need that extra variation for some important purpose, then go for it, but otherwise I’d say just go with a d6 pool.

      • Slipstream

        I was thinking random occurrences; a snake snugging up to you as your about to fire a sniper rifle, or a strap snapping, or mosquitos eating your face while you’re hiding from guards. All stuff that will make the rest of your day suck. But your right, this kind of thing can be handled by something like the “glitch” mechanic from Shadow Run.
        I understand the dice mechanic for LotR, and the Call Of Cthulhu sanity dice are not well loved.

  9. Dave L

    >add in your strength bonus, your base-attack bonus, your magic-weapon bonus, your terrain bonus, your dance-party bonus… Okay, I made one of those up

    Terrain bonus, right? You made up terrain bonus? I knew it!

  10. Dave L

    One problem I noticed w/ dice pools during your “Last Ship of the Republic” podcast:

    Set the number of passes to two, and the task is very easy. Set to four, and it’s quite difficult. Not much granularity there

    Adding and subtracting dice, changing the number a die needs to roll to pass, changing the explosion number… All of these give a wide swing. You can’t make slight probability adjustments, just big ones

    I’ve done the math

    • Oren Ashkenazi

      There’s a limit to the granularity for sure. In a system like Burning Wheel of Mouse Guard, where each die is a 50% chance of rolling a pass, each step up in difficulty requires two extra dice to make up for it. I personally haven’t found that to be a problem though, and I remember how in D&D and other systems with a finer grain, I usually skipped to multiples of 5 anyway.

      • Michael Campbell

        Well, what really matters with playable die styles are; dice-tempo and plot-tempo.

        If die rolls are few and “life or death” matters, then having higher granularity matters much more.
        If die rolls are many and the stakes are absorb-able then having faster die rolls at the price of giving up granularity becomes more important.

        The cliche’ is climbing a wall.
        I climb the wall and fail:- So I try again.
        I climb the wall and fail:- And break my special climbing claws, so I need to go to the blacksmith and spend some money.
        I climb the wall and fail:- And get overheard; breaking a branch falling back down, by a guard, on patrol. So now I’m in a sword fight that could get me killed.

        If die rolls are many, then fine tuning can come through the fact that the die rolls will be multiple. Basically a +1 on a D20 all the time is not all that different from a +1 on a D2 every tenth die roll, when considered over a period of 100 die rolls.

        Also it should be noted that Player experience of the game mechanics and GM experience of the game mechanics, can be quite different.

  11. Anthony Claok

    I think the pass-fail dice pool is the best way to explain the core dice mechanic program. Thanks for this post. Keep it up!

  12. Nicholas Fletcher

    There is actually a fifth lever you can pull as well: changing the size of the die. For example, if you need to roll 4 or higher, you’re more likely to do so on a d8 than a d6. I could see a Stat+Skill system where one sets the number of dice and the other sets the size.

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