How to use the Random Number Generator
- Enter the lowest and highest number.
- Choose how many numbers you want and whether repeats are allowed.
- Press Generate. Change any setting or press it again for a new draw.
How it works
Numbers come from your browser's cryptographic random number generator. The calculator also uses rejection sampling, which throws away the few raw values that would make some numbers slightly more likely, so every number in the range has exactly the same chance.
With "No repeats" each number can come up only once, like drawing tickets from a hat. With repeats allowed, every draw is independent, like rolling a die again and again. Negative numbers work too.
Formula
Chance of a given number = 1 ÷ (highest − lowest + 1) Ways to draw k of n without repeats = n! ÷ (k! × (n − k)!)
Example
Picking one number from 1 to 100 gives each number a 1% chance. Drawing 6 numbers from 1 to 49 with no repeats can produce 13,983,816 different sets, so the chance of matching all six is 1 in 13,983,816.
Ways to use it
- Pick a winner: number your entries, then generate one number from 1 to the number of entries.
- Classroom: choose students to answer by their number on the register, with no repeats so nobody is picked twice.
- Games: replace lost dice or spinners, or decide who goes first.
- Sampling: choose random rows or items to check from a list.
For official lotteries and prize draws, local laws may require a specific, audited process.
Frequently asked questions
Is this random number generator truly random?
It uses the browser's cryptographic generator, which is designed to be unpredictable, plus a method that removes bias. Each number in your range is equally likely.
How do I pick a random winner from a list?
Give each entry a number from 1 upward, then generate one number from 1 to the total. The entry with that number wins.
Can I generate negative numbers?
Yes. Enter a negative lowest number, for example −50 to 50.
How many numbers can I generate at once?
Up to 1,000. With no repeats, you can't ask for more numbers than the range contains.
Last reviewed October 21, 2026. Spotted an error? Tell us.