Math & Everyday
Random Number Generator
Generate random integers in any range, with or without repeats.
🔒 Runs entirely in your browser — nothing here is ever uploaded
CalcoTools · Random Number Generator · generated 8/23/2026, 1:05:09 PM
About the Random Number Generator
Generates random integers within a range you set, with an option to disallow repeated values — useful for drawing winners, sampling, or quick randomization tasks.
How to use it
- Enter a Minimum and Maximum.
- Enter How many numbers to generate, and toggle No repeats if needed.
- Click Generate to draw the numbers.
Formula
Uses a Fisher-Yates shuffle for unique draws, or independent random draws (with replacement) when repeats are allowed.
Worked example
Generating 5 unique numbers between 1 and 100 might return something like 7, 42, 88, 15, 63 — a different set each time.
Recommendations
- • Keep 'No repeats' checked for a true lottery-style draw where no number appears twice.
- • If the range is smaller than the count requested with no repeats allowed, widen the range or reduce the count.
- • The histogram that appears with 5+ results shows how evenly the draw is spread — a quick sanity check on randomness.
Frequently asked questions
It uses your browser's standard random number generator, suitable for games, sampling, and everyday randomization — not cryptographic-grade randomness like the Password Generator uses.