Random Number Generator

What is random number generator?

Random numbers are used for games, giveaways, sampling, classroom activities and decisions. A fair generator avoids the small bias that simple methods can add.

This tool uses your browser's secure random source and removes modulo bias, so every number in the range is equally likely.

How to use the random number generator

1. Set the minimum and maximum.
2. Choose how many numbers you need and whether they should be unique.
3. Press Calculate.

How the random number generator works

A random 32 bit value is drawn and values that would cause bias are discarded and redrawn. The remainder is mapped to your range.

Worked example

Common uses of the random number generator

• Picking a winner for a giveaway by entry number.
• Choosing random samples for surveys and classrooms.
• Deciding who goes first in a game.
• Creating test data and examples.
• Picking lottery style numbers for fun.

Tips and common mistakes

For giveaways, record the date and range so the draw is open and repeatable by rules.

Do not use online generators for gambling or security keys. Use proper systems for those.

Background: what to know before you rely on it

True randomness is hard for computers, which are built to be predictable. Most programs use a pseudo random generator that follows a formula from a seed. Browsers also provide a cryptographically secure generator that collects unpredictable data from the system. That is what this tool uses. Another subtle point is bias. If you take a random value and use the remainder to fit a range, some numbers can come up slightly more often. The tool avoids this by rejecting values from the uneven end of the range. For lotteries and gambling, regulated systems with audits are required.

Private, free and fast

This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all generators, or browse the full list of tools.

Related tools

Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. Do not use online generators for regulated draws or critical security keys.