How Random Number Generation Works
This tool uses your browser's built-in pseudorandom number generator: it starts from a seed and applies a deterministic algorithm that produces output statistically indistinguishable from true randomness for everyday purposes. Each number in your range has an equal probability of being picked.
With and Without Duplicates
- Allow duplicates: every draw is independent โ like rolling a die repeatedly.
- No duplicates: each number can appear only once โ like drawing names from a hat. The count cannot exceed the size of the range.
Common Uses
Giveaway winners, raffle draws, classroom cold-calling, game dice rolls, statistical sampling, and A/B test group assignment all need unbiased random picks. For classroom fairness, the no-duplicates mode guarantees nobody gets picked twice.
Is It Truly Random?
For games, giveaways, and sampling โ yes, effectively. For cryptography or security tokens, use a cryptographically secure generator instead; browser Math.random is not designed for secrets. Curious about the math of chance? Try our probability calculator.