1. What is a 20-Sided Die?

A 20-sided die (icosahedron) is a polyhedral die with twenty faces, commonly used in tabletop role-playing games like Dungeons & Dragons. Each face displays a unique number from 1 to 20.

2. How Probability is Calculated

The calculator uses the basic probability formula:

Where:

• \( P \) — Probability of a specific outcome
• 20 — Total number of possible outcomes

Explanation: For a fair 20-sided die, each outcome has exactly equal probability of occurring.

3. Understanding the Results

Details: The result shows both the decimal probability (0.05) and percentage (5%) for your selected outcome.

4. Using the Calculator

Tips: Simply enter any number between 1 and 20 to see its probability of being rolled on a fair 20-sided die.

5. Frequently Asked Questions (FAQ)

Q1: Is this calculator only for single outcomes?
A: Yes, this calculates probability for a single specific outcome. For ranges (e.g., 1-5), you would multiply by the number of outcomes.

Q2: Does this work for loaded dice?
A: No, this assumes a perfectly fair die where all outcomes are equally likely.

Q3: What's the probability of rolling a natural 20?
A: Exactly 5% (1 in 20 chance) on a fair die.

Q4: How does this compare to other dice?
A: A 20-sided die has lower individual outcome probabilities than common 6-sided dice (16.67% per outcome).

Q5: Can I calculate multiple outcomes?
A: For multiple specific outcomes (e.g., 5 OR 20), simply add their individual probabilities.