Random Number Generator
Generate random numbers in custom range
Generador de números aleatorios
Genera números aleatorios utilizando la API Web Crypto para mayor calidad de aleatoriedad. Ideal para sorteos, juegos, pruebas y simulaciones.
Online Random Number Generator - Integers and Decimals
How do random number generators work?
There are two families of generator: pseudorandom (PRNG) and truly random (TRNG). A PRNG uses a mathematical algorithm that, given a starting seed, produces a sequence that looks random but is deterministic: the same seed always yields the same sequence. They are fast and adequate for most uses. A TRNG derives randomness from physical phenomena such as thermal noise or radioactive decay, which is what serious cryptography requires. Modern browsers expose crypto.getRandomValues(), which is cryptographically secure and suitable for tokens and fair draws.
Applications of random numbers
Random numbers are fundamental to Monte Carlo simulations in financial and scientific modelling, video games for unpredictable NPC behaviour and procedural generation, fair raffles and lotteries, statistical sampling for surveys, password and session token generation, software testing with random inputs (fuzzing), cryptography for keys and nonces, and machine learning for weight initialisation and data shuffling. The quality of randomness required varies: a game tolerates a simple PRNG, while cryptography demands a CSPRNG.
Configuring ranges and distributions
This tool produces numbers with a uniform distribution, meaning every value in the range is equally likely. You can configure the minimum and maximum, negatives included, how many numbers to generate, whether the endpoints are included, and the number of decimal places. For other distributions such as normal, exponential or Poisson you will need specialised tooling or a mathematical transformation applied to uniform values. Uniform distribution is the correct choice for fair draws, random selection and most general use cases.
If you work with this tool, you will probably also find these useful UUID Generator, Password Generator, Lorem Ipsum Generator, Palette Generator.
Frequently asked questions
Are the generated numbers genuinely random?
We use the browser crypto.getRandomValues(), a cryptographically secure generator. For raffles, games and most applications it is effectively random and unpredictable. For high-grade cryptography or high-stakes gambling, consider a service backed by certified TRNG hardware such as random.org.
Can I use this for prize draws and contests?
Yes, for informal draws and small contests. The randomness is fair and cannot be manipulated. For legally regulated contests with significant prizes, check the requirements in your jurisdiction, since some demand a notary, an audit or a certified service. Either way, document the process: the time, the participants and the outcome.
How do I generate numbers without repetition?
To get N unique numbers from a range you have options: generate more than you need and drop duplicates, use a Fisher-Yates shuffle to pick N elements from a list, or generate sequentially while checking against what you already have. For small ranges, such as picking 6 numbers from 1 to 49, duplicate checking is perfectly efficient.
Why do I sometimes get the same number twice in a row?
That is mathematically normal. If you generate numbers from 1 to 10, each has a 10% chance on every draw, independent of previous results. Getting 7, 7, 7 three times running has a probability of 0.1%, unlikely but perfectly possible. A generator that remembered previous results would be biased, not truly random.