Custom Dice Roller

About the Custom Dice Roller

Not every situation calls for standard polyhedral dice. Sometimes you need a d7, a d30, or even a d100. Maybe you're designing a custom RPG system, running a probability experiment, or simulating events with non-standard outcomes. The Custom Dice Roller handles any configuration from d2 to d1000 with any number of dice.

Beyond basic rolling, This calculator supports modifiers, keep-highest/lowest mechanics, exploding dice (reroll on max), and adjustable minimum face values (so you can create d6s starting from 0 instead of 1). Quick presets cover common configurations like 2d6, 3d8, 1d20, and 4d10.

Use it when the die shape is unusual, the range is custom, or the rules call for exploding results and nonstandard minimums. The built-in statistics make it easy to compare a custom setup against the baseline behavior of ordinary dice.

When This Page Helps

Standard dice rollers limit you to common polyhedral shapes. Our custom roller removes all restrictions — any number of dice, any number of sides, with advanced mechanics like exploding dice and keep-best built in. It's the universal dice tool for game designers, probability students, and creative RPG systems.

The face frequency analysis also validates that digital dice produce uniform results, and the reference table makes it easy to compare statistical properties across dice types. Whether you're playtesting a new system or just curious about d37 probability, This calculator brings the key references together.

How to Use the Inputs

1. Enter the number of dice and sides per die, or pick a preset.
2. Adjust the modifier to add or subtract from the total.
3. Set the minimum face value (default 1, set to 0 for zero-indexed).
4. Choose keep mode for advantage/disadvantage mechanics.
5. Enable exploding dice if you want rerolls on maximum values.
6. Set the number of separate rolls to generate.
7. Click Roll and review individual dice, totals, and frequency analysis.

Example Calculation

Tips & Best Practices

• Use d2 for binary (coin flip) decisions within dice notation frameworks.
• A d3 is easily simulated as d6/2 rounded up, but a true d3 here is more elegant.
• The d30 and d100 are real dice used in some RPG systems for random tables.
• Compare d12 (avg 6.5) vs 2d6 (avg 7) to understand single-die vs multi-die distributions.
• Exploding d6 has an effective average of ~4.2 instead of 3.5 — a subtle but real boost.
• Run multiple rolls to generate entire encounter tables or random treasure hauls at once.

Dice Notation Systems

The NdS+M notation is universal in tabletop gaming. It extends to complex expressions like 4d6kh3 (roll 4d6, keep highest 3) and 2d10! (2d10 with exploding). While our tool uses drop-downs for readability, the underlying mechanics match any notation system.

Some systems extend further: Anydice uses expressions like "output 3d6+2d8", FATE uses special d6 with +/−/blank faces, and dice pool systems count successes rather than summing. Understanding these variations helps when designing or analyzing game mechanics.

Probability Distributions of Dice

A single die produces a uniform (flat) distribution. Adding multiple dice creates a bell curve: 2d6 forms a triangle, 3d6 approaches a normal curve, and 10d6 is nearly indistinguishable from Gaussian. This is the central limit theorem in action — the sum of many independent random variables tends toward normality regardless of the underlying distribution.

The speed of convergence depends on the die size. Smaller dice (d4, d6) converge faster because their underlying distribution is already symmetric and compact. Larger dice (d20, d100) need more dice before the bell curve emerges.

Game Design Applications

When designing RPG mechanics, the choice of dice profoundly affects feel. A d20 system (like D&D) has high variance — a skilled fighter can roll 1 and fail spectacularly. A 3d6 system (like GURPS) clusters results around 10-11, making skill levels more deterministic. Pool systems (roll Nd6, count successes) scale gracefully and reward investment linearly. Understanding these tradeoffs is essential for balanced game design.

Frequently Asked Questions

• What dice can I create?

  Any die from d2 (coin flip) to d1000. While physical dice beyond d120 don't exist, digital dice can have any number of sides with perfectly equal probability.

• What is dice notation?

  NdS+M means roll N dice with S sides each and add modifier M. For example, 2d6+3 means roll two six-sided dice and add 3 to the sum.

• How do exploding dice work?

  When a die shows its maximum value, you roll an additional die. If that also maxes out, you keep rolling. All results are summed. This creates theoretically unbounded results.

• What is the keep-highest mechanic?

  Roll more dice than you need and only count the best N results. This shifts the average upward and is used for advantage in D&D 5e and many other RPG systems.

• Why would I use a minimum face value of 0?

  Some systems use d6 with values 0-5 instead of 1-6. Setting the minimum to 0 makes the lowest face 0, which is useful for certain probability calculations and game designs.

• Can I roll d100 with This calculator?

  Yes! Set sides to 100 for a true d100 roll. This is equivalent to rolling two d10 dice (one for tens, one for units) but more convenient.