Click the number or press Generate — 20 possible outcomes
?The range 1 to 20 gives 20 equally likely outcomes with a 11 average. This range is used for D&D d20 rolls, rating scales, and decisions requiring up to 20 options. Each number has exactly 5% probability.
Probability: Each number from 1 to 20 has exactly 5% probability on every roll. This is a discrete uniform distribution — there is no bias toward any particular value, and past results never influence future ones.
Common uses for this range: Percentage-based probability, guessing games, random selection from up to 20 items, statistical demonstrations.
This tool runs entirely in your browser. No data is sent to any server, no results are logged, and the generator re-seeds on every click.
Click the large number or press Generate. A random integer between 1 and 20 is selected with 5% probability for each value. You can also adjust the range using the fields above.
Yes. Math.random() in modern browsers uses a cryptographically seeded algorithm producing a uniform distribution. Each of the 20 integers between 1 and 20 has exactly equal probability.
The statistical mean of the range 1 to 20 is 11. Over many rolls, your results will converge toward this value. The standard deviation is approximately 5.77.
Use our Number Generator to generate up to 20 numbers at once with a no-repeats option — ideal for lottery picks and random sampling.