Random Number Generator
Crypto-secure draws · ranges, list picks & lottery lines
Ideal for giveaways, classroom name draws, secret-santa order or splitting a class into teams. Commas work too if you paste everything on one line.
Every line is drawn without replacement and sorted, exactly like a real machine. Bonus balls come from their own pool and are highlighted in amber.
Advanced: repeatable seed
Leave this empty and every draw uses your browser's cryptographic random source. Type any word or number and the same seed always reproduces the same draw, which is handy for research samples, A/B splits and anything you need to prove later.
How to Use
- 1Pick a mode: a number range, a list of names, or a lottery game.
- 2Set the limits and how many values you want back.
- 3Turn duplicates off when every result must be different.
- 4Hit Generate, then Copy, or Draw again for a fresh set.
How Random Is It?
- Sourcecrypto.getRandomValues()
- MappingRejection sampling, zero modulo bias
- ShufflingFisher-Yates, uniform over subsets
- PrivacyRuns in your browser, nothing sent
Quick Examples
Tap an example to load it above.
Everything about the Random Number Generator
What "random" actually means online, and how to pick numbers you can defend.
A random number generator produces values with no pattern anyone can predict from the values that came before. This one draws every result from your browser's cryptographic random source, maps it onto your range without bias, and never sends a single number to a server.
Use it to pick a winner, choose a sample, break a tie, generate a PIN, split a class into teams, or fill in a lottery line. Three modes cover almost every request: a number range, a list pick, and a lottery draw.
Why "unbiased" matters: the naive way to squeeze a 32-bit random value into 1 to 100 is a remainder, but 2³² is not divisible by 100, so the first 96 numbers come up very slightly more often. This generator throws away the leftover values and redraws instead, so every number in your range is exactly equally likely.
Pseudo-random vs cryptographically secure
Most online generators call Math.random(). It is fast, it is fine for a raffle, and it is
predictable: an observer who sees enough outputs can work out the internal state and forecast the
rest. Anything that guards money, access or privacy needs a cryptographically secure generator instead.
| Source | Predictable? | Good for |
|---|---|---|
| Dice, coins, cards | No | Games, small draws |
Math.random() | Yes, with effort | Games, shuffling, demos |
crypto.getRandomValues() | No | PINs, tokens, tie-breaks, audits |
| Seeded generator | By design | Reproducible research samples |
When to allow duplicates, and when not to
- 1Allow duplicates for independent events
Rolling a die twice, simulating coin flips, or generating test data. Each draw should be able to repeat a previous result, and blocking repeats would actually make the model wrong.
- 2Block duplicates for selections
Picking 10 students from a class of 50, drawing lottery balls, or choosing raffle winners. One name can only come out once, so switch duplicates off.
- 3Match the count to the pool
You cannot draw 20 unique numbers from a range of 10. The generator will say so rather than loop forever.
- 4Sort last, not first
Sorting is cosmetic and never changes which numbers were drawn. Keep "draw order" when the order itself matters, such as first, second and third prize.
The seed field, and why you might want one
A seed turns randomness into something you can repeat. Enter survey-2026 and you will get the
same sample every time you press Generate, on any device, in any browser. That is exactly what a reviewer
wants when they ask how you chose your sample. Clear the field and the generator goes back to true,
non-repeatable randomness.
Fair odds, honestly stated
In lottery mode the tiles show the real number of possible tickets: 13,983,816 for a 6/49 game, about 292 million for Powerball. Every line this tool produces is exactly as likely as every other line, including 1-2-3-4-5-6. Random numbers cannot improve your odds; they only stop you sharing a jackpot with the thousands of people who all picked birthdays.
Frequently Asked Questions
How do I generate a random number between 1 and 100?
Stay on the Number range tab, set the lower limit to 1 and the upper limit to 100, leave "How many" at 1 and press Generate. Both limits are included, so 1 and 100 can both come up. Change "How many" to draw a whole set at once.
Are these numbers truly random?
They come from your browser's cryptographic random source, crypto.getRandomValues(), which is seeded by operating-system entropy such as hardware timing noise. It is not predictable from previous outputs, unlike the Math.random() generator most calculator sites use. The only way to repeat a draw is to type a seed yourself.
Can I generate numbers with no repeats?
Yes. Set "Allow duplicates" to "No (all unique)". The generator then shuffles the range and deals from it, so every value is different. You cannot ask for more unique values than the range holds; requesting 20 unique numbers from 1 to 10 returns a clear warning instead of running forever.
How do I pick a random winner from a list of names?
Switch to the "Pick from a list" tab, paste your entries one per line (a single comma-separated line also works), choose how many winners you need and press Pick winners. With repeats blocked, each name can only be drawn once, so you can pull first, second and third place in a single draw.
What does the seed field do?
It makes a draw reproducible. The same seed with the same settings always produces the same numbers, on any device, which is what you need to document a research sample or prove a draw was not re-rolled. Leave the field blank for true, one-off randomness.
Can I use this generator for passwords or security tokens?
The random source itself is cryptographically secure and nothing leaves your browser, so a PIN or numeric token generated here is sound. For a full password use a dedicated password manager instead, because you want mixed characters and secure storage, not just digits.
Do random lottery numbers improve my chances of winning?
No. Every line has identical odds, 1 in 13,983,816 for a 6/49 game. What a random line does change is who you share a jackpot with: most people pick birthdays, so numbers above 31 are chosen far less often and a random line is less likely to be a shared win.
Is the random number generator free and does it work offline?
Yes. It is 100% free with no sign-up, and every draw is computed inside your browser, so no number is ever transmitted or logged. Once the page has loaded it keeps working even if your connection drops.