Random Number Generator
This version of the generator creates a random integer. It can deal with very large integers up to a few thousand digits.
Comprehensive Version
This version of the generator can create one or many random integers or decimals. It can deal with very large numbers with up to 999 digits of precision.
Allow duplication in results?
Sort the results?
Type of result to generate?
What is a random number?
A random number is a number drawn from a pool of limited or unlimited numbers with no discernible pattern that would let anyone predict it. The draws are almost always independent of each other: each result has the same chance regardless of what came before. A pool of numbers can also follow a distribution — the heights of students in a school, for instance, cluster around the median height in a normal distribution, so a randomly picked student is more likely to be near the middle than very tall or very short. The generators above instead spread their numbers evenly (uniformly) across the whole range you set, and every draw is independent.
Hardware and pseudo-random generators
A random number generator is any device or program that produces numbers within a defined scope. Hardware generators rely on physical processes — dice, coin flips, atmospheric or thermal noise, and other quantum phenomena — to produce true randomness. Computer-based generators are almost always pseudo-random: algorithms whose output approximates the statistical behavior of truly random sequences without being truly random. The generators on this page are pseudo-random in that sense (powered by your browser's cryptographic randomness source), and like all software generators they suit games, sampling, and simulations well, but should not be used for cryptographic purposes such as generating keys or passwords.
Frequently Asked Questions
Are the generated numbers really random?
They are pseudo-random: CalcNova generates them locally in your browser using the Web Crypto API, which provides cryptographically strong randomness. That is more than sufficient for games, sampling, simulations, and everyday choices — but like all software generators, it should not be relied on as a source of true randomness from a physical process.
How big can the numbers be?
The simple generator works with integers of a few thousand digits, and the comprehensive generator supports up to 999 digits of decimal precision. All arithmetic is exact, so no range is too large to sample uniformly.
How do I generate numbers without repeats?
In the comprehensive generator, request more than one number and set "Allow duplication in results?" to No. Every number in the set will then be unique. If the range contains fewer distinct values than the amount requested, the generator says so instead of looping forever.
How many numbers can I generate at once?
The comprehensive generator creates up to 999 numbers per run, and can sort them in ascending or descending order.