Random Number Generator

Written byOleh Soloninupdated 5 October 2026

Min

Max

Whole numbers only

How many numbers

No repeats

Each number comes up at most once — for a draw with several winners.

Result

Random number100
All numbersgenerated in your browser…

A fair pick between your two limits

Random numbers in any range — one or several at once, with or without repeats. For giveaways, dice rolls, sampling and settling arguments.

Sometimes you need a number nobody chose. Prize draws, picking a test case, deciding who goes first — all of them want an unbiased pick within a range you set.

The randomness comes from the browser's cryptographic generator, the same source that secures your connections, and every number in the range has the same chance. Both ends are included, so a 1-to-6 range behaves like a die.

How to use

Set the minimum and the maximum. For a giveaway, that is 1 to the number of entries.
Choose how many numbers you need. With several winners, tick No repeats so that one entry cannot win twice.
Press Generate again for a fresh set with the same settings.
For decimals, untick Whole numbers only; the result then carries six decimal places.

Running a fair giveaway

A draw is fair because of the order of events, not because of the generator. Close entries first and number the entrants — say, in the order of their comments — and publish that list. Only then set the range from 1 to the last number and press the button. If the number is picked before the list is fixed, no generator will protect you from suspicion.

The odds are straightforward. Among 250 entrants each wins with a chance of 1 in 250, or 0.4 percent. With three prizes and No repeats on, each entrant has a 3 in 250 chance — 1.2 percent — of being among the winners. If a winner declines or broke the rules, redraw only that place: leave their number out and draw one more.

The generator keeps no record of results. For a public draw, record the screen or stream from the moment the range is visible and say the time; that is usually enough for nobody to dispute the outcome.

With repeats and without

With repeats, every number is drawn afresh, independent of the previous ones — like rolling a die. Without repeats, a number that has come up is out — like a ball taken from a lottery drum. Several winners need the second mode; a run of dice rolls or random scores needs the first.

Repeats turn up more often than intuition suggests. Drawing from 1 to 100 with repeats, ten numbers already contain at least one match 37 percent of the time. It is the birthday paradox at work: there are far more pairs that could match than there are numbers.

Chance of a repeat = 1 − (100 × 99 × … × (100 − k + 1)) / 100^k.
Numbers drawn from 1 to 100	Chance of at least one repeat
5	9.7%
10	37.2%
20	87.0%
30	99.2%

Where the randomness comes from

The numbers come from crypto.getRandomValues, the generator the browser takes from the operating system and uses for encryption keys. Unlike the everyday Math.random, its sequence cannot be reconstructed from a handful of numbers it has produced.

To make the chances exactly equal, the random bits are assembled into a whole number below 2⁵³, and values from the incomplete tail that does not divide evenly by the size of the range are thrown away and drawn again — so in any range every number has the same chance on each draw. The no-repeats mode is a partial Fisher–Yates shuffle built on the same draws, so every combination of winners is equally likely.

What this calculator shows

One or several random numbers within your chosen range
Inclusive limits, so both endpoints can come up
A fresh draw with the Generate again button

What to keep in mind

Randomness comes from the browser's cryptographic generator, not from Math.random.
With repeats each draw is independent of the last; without repeats a number is out once it has come up.

FAQs

Is it genuinely random?

It comes from the browser's cryptographic generator, the one used to secure connections. The next number cannot be predicted from the ones already drawn, and every number in the range has the same chance.

Can the same number appear twice in a row?

With repeats, yes, and it should: each draw is independent, and a generator that never repeated would be the biased one. If repeats are unwanted, tick No repeats.

How do I draw several winners without duplicates?

Enter the number of winners in How many numbers and tick No repeats. If the range holds fewer numbers than you need, the calculator says so.

Are both the minimum and maximum included?

Yes. A range of 1 to 10 can return 1 or 10, giving all ten values an equal chance.

Can I prove the draw was fair?

The generator does not store results. Publish the numbered list of entrants before the draw, then record the screen or stream from the moment the range is visible and state the time — that makes the result checkable.

Are the numbers truly random?

They come from crypto.getRandomValues, the browser's cryptographically secure generator — the one used for encryption keys — so the next number cannot be predicted from earlier ones. The page is still a number picker rather than a key generator: for passwords and tokens use a tool built for that format.

Can I rule out repeats?

Yes, with the no-repeats mode, where each number appears once as in a draw. In the ordinary mode repeats are allowed and turn up more often the narrower the range.

Worked example

Three winners among 250 entrants

Input: Range 1 to 250, three numbers, no repeats

Output: Three different numbers, e.g. 137, 12 and 208

Note: Each entrant has a 3 in 250 chance, or 1.2%, of being among the winners. Generate again repeats the draw with the same settings.

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Result

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