Random Number Generator
Pick random integers in a range (client-side).
This random number generator produces a random integer between a minimum and maximum value you choose, entirely inside your browser. Nothing is sent to our servers, and each click produces an independent draw, making it useful for games, classroom demonstrations, raffles, and simple statistical sampling exercises.
"Random" can mean different things depending on the stakes involved. For games, contests, and teaching, a good pseudo-random number generator (PRNG) feels unpredictable enough. For anything security-sensitive — passwords, tokens, or cryptographic keys — you need a cryptographically secure random number generator (CSPRNG) instead, which follows stricter mathematical guarantees.
On this page
Generating a Uniform Random Integer
A uniform random integer generator between a minimum and maximum (inclusive) gives every whole number in that range an equal chance of being selected. The calculator draws a random floating-point value in [0, 1), scales it to the size of your chosen range, and rounds down to land on a whole number within bounds.
For example, generating a number between 1 and 6 mimics rolling a fair six-sided die: each of the six outcomes should appear roughly one-sixth of the time over many draws, though any individual small sample can look uneven purely by chance.
Why "Feels Random" Is Not the Same as Truly Random
Most software-based random number generators are pseudo-random: they use a deterministic mathematical formula seeded by some starting value, which means the same seed always reproduces the same sequence. This is perfectly fine for games and sampling, but it means the sequence is theoretically predictable if someone knows the seed and algorithm.
True randomness (or cryptographically strong pseudo-randomness) draws from unpredictable physical or system-level entropy sources, such as timing jitter or hardware noise, and is required whenever predictability would create a real-world risk — for example, generating account passwords or security tokens.
Common Uses for a Simple Random Number Generator
A lightweight browser-based generator like this one covers most everyday needs where "good enough" randomness is exactly what is required.
- Deciding turn order in board games or classroom activities.
- Picking a winner from a numbered list of entries in a small raffle or giveaway.
- Generating sample data for statistics homework or Monte Carlo intuition-building.
- Choosing a random practice question, exercise, or writing prompt from a numbered list.
For anything security-related, use our Password Generator instead, which relies on your browser’s cryptographic RNG rather than a simple uniform-integer generator.
Sampling With or Without Replacement
"With replacement" means each draw is independent and previously generated numbers can appear again — like rolling a die repeatedly. "Without replacement" means each value can only be selected once, like drawing raffle tickets from a bag without putting them back.
This tool generates independent draws (with replacement) by default. If you need unique, non-repeating numbers — for example, assigning distinct raffle numbers to distinct people — you will need to discard duplicate draws manually or use a shuffle-based method instead.
A Brief History of Randomness in Computing
Early computers generated "random" numbers using simple mathematical recurrence formulas seeded by something like the system clock, which was good enough for simulations and games but never intended to resist a determined attacker. As computing moved online, security-critical applications needed something stronger, leading to cryptographically secure pseudo-random number generators (CSPRNGs) that draw on operating-system-level entropy sources such as hardware timing jitter, disk activity, and user input timing.
Modern browsers expose this stronger randomness through the Web Crypto API, which is what powers tools intended for secrets, like our Password Generator, while simpler Math.random()-style generators remain perfectly adequate for games, contests, and classroom demonstrations like this page.