Dice Systems: d20, Dice Pools, and Percentile
Quick Answer: Beginners should start with the d20 system used in D&D 5e as it’s the most common and well-supported. Dice pools offer more consistent results while percentile systems are the easiest to understand mathematically. Choose based on whether you prefer swingy excitement (d20), reliability (dice pools), or simplicity (percentile).
Tabletop role-playing games (TTRPGs) use different dice systems to determine the outcomes of actions, from swinging a sword to persuading a guard. The dice system a game uses affects how the game feels and how easy it is to learn. This guide explains the three most common systems—d20, dice pools, and percentile—and touches on alternatives like card-based and diceless systems.
Why the Dice System Matters
The dice system is the core mechanic of a TTRPG. It decides how players resolve actions and how much randomness is involved. Different systems create different experiences. For example, a d20 system emphasizes big swings in outcomes, while a dice pool system tends to feel more consistent. The system also affects how fast the game plays and how much math is involved.
Choosing the right system can make a big difference for beginners. Some systems are easier to learn, while others require more familiarity with probability or game mechanics. Understanding the basics of each system helps you pick a game that matches your preferences and skill level.
The d20 System (D&D, Pathfinder)
The d20 system is the most popular dice system in TTRPGs, used in games like Dungeons & Dragons and Pathfinder. It’s named after the 20-sided die (d20), which is the primary die used for most actions. In this system, players roll a d20, add modifiers based on their character’s abilities, and compare the result to a target number to determine success or failure.
For example, if your character tries to climb a wall, the Game Master (GM) might set a difficulty class (DC) of 15. You roll a d20, add your character’s Strength modifier, and if the total equals or exceeds 15, you succeed. If not, you fail. This system is straightforward but can feel unpredictable because a single roll has a wide range of outcomes (1 to 20).
The d20 system also uses other dice for damage rolls and specific effects. For instance, a sword might deal 1d8 damage, meaning you roll an 8-sided die to determine how much harm it causes. This combination of a d20 for actions and other dice for damage makes the system versatile but slightly complex for beginners.
One challenge for new players is understanding modifiers and how they affect rolls. Every character has stats like Strength and Dexterity, which provide bonuses or penalties to rolls. Learning how these work takes time, but once you grasp the basics, the system becomes intuitive.
Dice Pool Systems (Blades in the Dark, World of Darkness)
Dice pool systems, used in games like Blades in the Dark and World of Darkness, work differently from d20 systems. Instead of rolling one die, players roll multiple dice (the “pool”) and count how many meet or exceed a target number. The size of the pool depends on the character’s skills and the situation.
For example, in Blades in the Dark, if your character tries to pick a lock, you might roll a number of six-sided dice (d6s) equal to your character’s skill level. Each die that rolls a 4, 5, or 6 counts as a success. The more successes you get, the better the outcome. This system creates a more consistent range of results compared to the d20 system.
Dice pool systems often include mechanics for critical successes or failures. In World of Darkness, rolling a 10 on a d10 counts as two successes, while rolling a 1 cancels out a success. These rules add depth but can be confusing for beginners who aren’t used to tracking multiple dice and outcomes.
One advantage of dice pool systems is that they feel less random than d20 systems. Because you’re rolling multiple dice, extreme outcomes (like a critical failure) are less common. However, managing a large pool of dice can be cumbersome, especially if you’re playing online or don’t have many dice on hand.
Percentile Systems (Call of Cthulhu)
Percentile systems, used in games like Call of Cthulhu, are based on rolling two 10-sided dice to generate a number between 1 and 100. One die represents the tens digit, and the other represents the ones digit. For example, rolling a 3 and a 7 results in a 37. Players compare this number to their character’s skill or ability to determine success or failure.
In Call of Cthulhu, if your character has a 60% chance to pick a lock, you roll percentile dice and succeed if the result is 60 or lower. Rolling a 61 or higher means you fail. This system is straightforward because the percentage directly reflects the chance of success, making it easy for beginners to understand.
Percentile systems often include rules for critical successes and failures. In Call of Cthulhu, rolling a 01 is usually a critical success, while rolling 00 or 100 is a critical failure. These rules add excitement but can also lead to unexpected outcomes, especially in tense situations.
One downside of percentile systems is that they can feel less dynamic than other systems. Because skills are represented as percentages, there’s less room for modifiers or creative problem-solving compared to d20 or dice pool systems. However, this simplicity makes percentile systems a good choice for beginners who want to focus on storytelling rather than mechanics.
Card-Based and Diceless Systems
Some TTRPGs don’t use dice at all. Instead, they rely on cards or other mechanics to resolve actions. For example, Dread uses a Jenga tower—players pull blocks to succeed, and if the tower collapses, their character fails. This creates a tense, physical experience that’s very different from rolling dice.
Card-based systems, like certain storytelling games, use decks of cards to determine outcomes. Each card has a unique effect, and players draw cards to resolve actions. This system adds variety but can be harder to learn because it requires understanding the deck’s rules and interactions.
Diceless systems, like Amber Diceless Roleplaying, don’t use randomizers at all. Instead, outcomes are determined by comparing character stats or negotiating with the GM. This approach emphasizes storytelling and strategy but can feel less exciting for players who enjoy the unpredictability of dice.
These systems are less common than d20, dice pool, or percentile systems but offer unique experiences. They’re worth exploring if you want something different or if you’re playing with people who don’t like dice.
Which to Start With
For complete beginners, the d20 system is a good starting point because it’s widely used and well-documented. Games like Dungeons & Dragons have plenty of resources to help new players learn the rules. However, the d20 system can feel unpredictable, so if you prefer more consistent outcomes, a dice pool system might be better.
Percentile systems are another good option for beginners because they’re easy to understand. Games like Call of Cthulhu are great for players who want to focus on storytelling rather than complex mechanics. However, percentile systems can feel less dynamic than other systems, so they might not appeal to everyone.
If you’re looking for something completely different, card-based or diceless systems offer unique experiences but can be harder to learn. These systems are best for players who already have some experience with TTRPGs or who want to try something unconventional.
Frequently Asked Questions
Q: What’s the easiest dice system for complete beginners?
Percentile systems are mathematically simplest since percentages match everyday intuition, though D&D 5e has the most learning resources.
Q: Why would I choose dice pools over d20?
Dice pools produce more consistent results - great for players who dislike the extreme swings of a d20 system.
Q: Do I need special dice for percentile systems?
No, you can use two standard d10s (one marked as tens