Random Number Generator

It is a pseudorandom generator. The calculator uses Web Crypto when available and Math.random only when Web Crypto is absent. Its integer path uses rejection sampling for supported ranges. It is useful for casual draws and simulations, but it is not an auditable physical-randomness service or a certified contest system.

You can use it for an informal draw by assigning entry numbers and requesting unique integers. For a regulated promotion, use rules, recordkeeping, and a drawing method that meet the applicable jurisdiction and platform requirements. This page does not create an audit trail or certify the draw.

You can request up to 1,000 results. In integer mode, the inclusive range can contain up to 2^53 distinct values because the rejection sampler combines random values into a 53-bit sample. Both endpoints must remain within JavaScript's safe-integer range.

For integers, it fails when you request more unique numbers than the range contains - for example, 10 unique integers between 1 and 5 is impossible. In decimal mode, values are generated as JavaScript numbers without display rounding before uniqueness is checked. A very narrow range can still fail because the generator stops after a bounded number of attempts.

It prevents repeats. In integer mode, the calculator samples without replacement, so every feasible set of requested values has the same probability. Selecting unique values does not make one individual value more likely than another.