🎲 Random Number Between 1 and 100

What is the Random Number Between 1 and 100?

A random number between 1 and 100 is one of the most common ranges people reach for, whether for a quick guessing game, a classroom demo, or just settling something without bias. This tool defaults the minimum to 1 and the maximum to 100, giving exactly 100 equally likely whole number outcomes, and you can still change either field if you need a wider or narrower range.

Fairness comes from the Web Crypto API, the same cryptographically secure randomness source browsers use for security tasks, rather than a simple seeded formula. A subtlety specific to a range of 100 is that 4,294,967,296 (2^32, the size of a 32-bit random value) does not divide evenly by 100. A naive script that just takes a random 32-bit number modulo 100 would make the numbers 1 through 96 microscopically more likely than 97 through 100. This tool avoids that by using rejection sampling: it discards the small leftover slice of raw values that would cause the imbalance and only keeps values from the part of the range that divides cleanly by 100, so all 100 outcomes stay genuinely equal.

The duplicates toggle changes how repeated draws behave. With Allow duplicate numbers ticked, each number is picked independently, so the same value can appear more than once across multiple draws, similar to rolling a 100-sided die repeatedly. Untick it and the tool switches to drawing without replacement using a partial Fisher-Yates shuffle, so every number in your batch is unique. Because the pool only has 100 values total, unique mode caps out at 100 numbers per batch.

When to use it

• Playing the classic "guess a number between 1 and 100" game with friends, students, or over a call.
• Picking one raffle or giveaway winner when entries are numbered up to 100.
• Drawing several unique winners from up to 100 numbered entries with duplicates turned off.
• Settling a quick decision fairly instead of relying on a coin flip or a single die.
• Generating sample values for a spreadsheet, classroom exercise, or programming practice that calls for numbers from 1 to 100.
• Demonstrating probability or statistics concepts where every one of 100 outcomes needs to be equally likely.

How to use the Random Number Between 1 and 100

1. Leave Minimum at 1 and Maximum at 100 for the standard range, or edit either field if you need something different.
2. Set How many to the number of results you want in one batch.
3. Tick Allow duplicate numbers for independent picks, or untick it for unique numbers with no repeats.
4. Optionally tick Sort results ascending to read the numbers in order.
5. Click Generate for a fresh result, then Copy to put it on your clipboard.

Formula & method

Worked examples

Nearby ranges and what they suit

How the duplicates toggle changes the result

Common mistakes to avoid

• Requesting more than 100 unique numbers. With duplicates off, the tool cannot draw more than 100 numbers, since only 100 distinct values exist between 1 and 100. Asking for more shows an error; either reduce how many or allow duplicates.
• Thinking 100 is excluded from the range. Both ends of the range are included. A draw between 1 and 100 can return 1 or 100 just as easily as any number in between, giving the full 100 possible values, not 99.
• Reading too much into a short run. In a handful of draws you might see the same number twice, or a cluster of high numbers with no low ones. That is ordinary randomness, not a fault in the generator; fairness only becomes visible across many draws.
• Assuming a plain modulo trick would be fair for 100. Because 4,294,967,296 (2^32) does not divide evenly by 100, code that takes a random 32-bit value modulo 100 would make the numbers 1 through 96 marginally more likely than 97 through 100. This tool avoids that by rejecting the uneven leftover before mapping the value onto 1 to 100.

Glossary

Random number generator (RNG)

A process that produces numbers that are hard to predict, with each allowed value equally likely within the chosen range.

Uniform distribution

A spread where every value in the range has exactly the same probability of being chosen, so no number is favoured.

Cryptographically secure

Randomness drawn from a high-quality system source that cannot be predicted or reproduced, as provided by the Web Crypto API.

With and without replacement

With replacement means each pick is independent and numbers can repeat. Without replacement means each value is used at most once, like dealing cards.

Modulo bias

A subtle skew that appears when a large random value is reduced with the remainder operator and the range does not divide evenly, making some numbers slightly more likely.

Rejection sampling

A technique that discards the small slice of raw random values that would cause modulo bias, keeping only values from the part of the range that divides evenly.

Frequently asked questions