Random Number Generator

What is a random number generator?

A random number generator, or RNG, picks a number in a range you choose so that every number has the same chance of appearing. Nobody, including you and the tool, can predict the next result. It is the digital version of rolling a die, drawing a name from a hat or spinning a wheel, only faster and without any bias.

Set a minimum and a maximum, choose how many numbers you need, and press Generate. You can ask for whole numbers or decimals, allow repeats or forbid them, and sort the result if you want it in order.

Popular ranges people use

Most people need one of a few common ranges. The preset buttons above fill in the settings for you:

• Dice, 1 to 6: A fair virtual die for board games, classroom games and quick decisions.
• 1 to 10: Pick a number for a guessing game, a rating or a team member.
• 1 to 100: The classic random number between 1 and 100, used for games, draws and tests.
• 1 to 1000: A wider range for raffle tickets, order numbers and sampling.
• Lottery, 6 of 49: Six different numbers sorted from smallest to largest, in the style of many lottery draws.

With repeats or without repeats

Whether a number can appear twice depends on what you are doing. Rolling a die is a draw with repeats, because the same face can come up again and again. Drawing raffle tickets or lottery balls is a draw without repeats, because a ticket that has been drawn is out of the box. Tick No repeated numbers for the second kind.

Repeats in random data are normal. In a group of just 23 people, the chance that two share a birthday is already a little over 50 percent. If you generate numbers with repeats allowed and see the same value twice, the generator is not broken, it is behaving like real chance.

Whole numbers and decimals

With 0 decimal places you get whole numbers. Raise the number of decimal places, up to 6, and you get values such as 7.25 or 0.381942. Decimals are useful for sample prices, measurements, probabilities between 0 and 1 and test data for spreadsheets and programs.

How computers create random numbers

Many programs use a pseudo-random generator, which follows a formula that only looks random. That is fine for a simple game but not for anything that needs fairness or security. Our generator asks your browser for numbers from its cryptographically secure random source, which is fed by unpredictable data from your device.

We also avoid modulo bias, a common mistake where some numbers become slightly more likely than others. Values that would unbalance the range are thrown away and drawn again, so every number in your range has exactly the same chance.

What can you use it for?

• Giveaways and raffles: Number your entries, set the range and draw a winner without any argument.
• Games: Roll dice, choose who goes first or pick a secret number.
• Classrooms: Call on students by their roll number so everyone gets a fair turn.
• Decisions: Assign options to numbers and let chance choose when you cannot.
• Sampling and statistics: Pick random items from a numbered list to avoid choosing only the easy ones.
• Testing and programming: Create sample values, IDs and data for tests.

Random does not mean due

A common mistake is to believe that a number is due. If a die has shown a six three times in a row, the next roll is still a one in six chance, because the die has no memory. The same is true here. Each press of Generate is completely independent from the one before it, and no number can be lucky or overdue.

For the same reason, a random generator cannot improve your chances in a lottery. It only picks numbers fairly, and every combination is equally likely to win.

Tips for a fair draw

• Number the entries first: Give every person or ticket a clear number before you start.
• Set the exact range: Use 1 as the minimum and the number of entries as the maximum.
• Turn on no repeats for several winners: Each winner is then a different person.
• Keep a record: Take a screenshot of the result if others need proof.
• Check the local rules: Contests and giveaways can have legal requirements in some places.

Why use our free random number generator?

• Secure and unbiased: Built on the browser's cryptographic random source.
• Flexible: Whole numbers or decimals, with or without repeats, up to 1,000 numbers at once.
• Handy extras: Presets, sorting, sum, average and one-click copy.
• Private: Nothing is uploaded, stored or tracked.
• Free: No signup, no limits and nothing to install.