CalcWhenRandom Number Generator
One random number between 1 and 100 is the classic draw — press the button and the panel shows it big, with batches of up to 100 numbers and a no-repeats mode for raffles and picking names from a hat, numerically speaking.
How it works
Set the range, set how many, press generate. With “no repeats” off, each number is an independent draw — the same value can come up twice, as it should in honest randomness. With it on, the tool shuffles the whole range and deals from it, guaranteeing unique numbers for raffles, lotteries of your own, sample selection and turn order.
If unique mode asks for more numbers than the range contains, the tool caps at the range size rather than looping forever — the honest behaviour, stated here rather than discovered.
The method
Draws use crypto.getRandomValues with rejection sampling, giving every integer in the inclusive range equal probability. Unique mode performs a Fisher–Yates shuffle of the full range and takes the first N, which is exactly dealing from a shuffled deck.
Frequently asked questions
Are the numbers really random?
They come from your device's cryptographic random source — the same quality of randomness used for security keys. No seed, no pattern, no memory between presses.
Why did I get the same number twice?
Because repeats are genuinely possible: drawing 1–10 twice gives a match about one time in ten. If your use cannot tolerate repeats, tick “no repeats”.
Can it pick lottery numbers?
It can pick numbers in any range, uniquely if you tick the box. It cannot improve your odds — every combination in a fair lottery is equally likely, which is exactly the property this generator guarantees.