What is a random number generator?
A random number generator (RNG) produces values within a defined range without any predictable pattern. Online RNGs like this one use JavaScript's Math.random() function — a pseudo-random number generator seeded by the browser — which is more than sufficient for games, raffles, testing, and everyday decisions. The output cannot be predicted in advance and is uniformly distributed across the range.
Common uses
Lottery and raffles: Pick winning numbers or raffle ticket holders fairly. Games: Simulate dice rolls, card draws, or board game events. Statistics and sampling: Select random data points or sample indices. Decision making: Resolve ties or make a fair random choice between options. Software testing: Seed test data or generate random IDs for mock records.
Duplicates and unique numbers
With "Allow duplicates" checked, the same number can appear multiple times — like rolling a die where any face can land twice. With duplicates disabled, every result is unique, like drawing tickets from a hat without replacement. If you request more unique numbers than the range contains (e.g. 10 unique numbers between 1 and 5), the tool will show an error rather than silently produce incorrect output.
How the numbers are distributed
Each number in the range has an equal probability of being selected on any given draw. For a range of 1–10, each value has exactly a 10% chance per draw. Over a large number of draws the distribution should approach uniform — but short runs will naturally show variation. This is not a bug; it is how true randomness behaves.