Random Number Generator
Generate cryptographically secure random numbers. Set range, count, and uniqueness options.
Enter a minimum and maximum to generate a random number, or generate multiple numbers with optional unique-only mode. Uses the browser's crypto-strength random source.
Useful for games, sampling, test data, and informal draws. For regulated competitions or audit-heavy processes, keep a separate record of your rules, entries, and results.
Good to know before generating numbers
The generator works with whole numbers. Set the smallest and largest allowed value first, then choose whether each result may repeat.
Unique mode has a limit
You cannot ask for 20 unique numbers from a range that only contains 10 possible values.
Negative ranges work
A range such as -50 to 50 is valid. The lower and upper values are sorted before generation.
Duplicates can be valid
With duplicates allowed, every draw is independent. Seeing the same value twice is not an error.
Copy important results
Results stay in the current page state. Copy them before you refresh or navigate away.
Count is capped
The page limits each run to 1,000 values so the browser remains responsive.
Whole numbers only
For decimal values, generate an integer first and scale it to the precision you need.
How Random Number Generation Works
Not all randomness is created equal. When you flip a coin, that's physical randomness, governed by air resistance, force, and a dozen variables nobody can predict. Computers don't have that luxury. They're deterministic machines, so they need clever algorithms to produce numbers that behave like random ones.
This tool uses the Web Crypto API (crypto.getRandomValues), which taps into your operating system's cryptographic random number generator. It's the same source used for generating encryption keys and secure tokens. That makes it far stronger than Math.random(), which uses a predictable pseudo-random algorithm.
The practical difference? Math.random() is fine for shuffling a playlist. But for anything where someone might try to predict or manipulate the outcome, lotteries, prize draws, security tokens, you need cryptographic randomness. That's what you get here.
Random vs Pseudo-Random
| Property | Math.random() (PRNG) | Crypto API (CSPRNG) |
|---|---|---|
| Predictable? | Yes, if seed is known | No, entropy-based |
| Speed | Extremely fast | Fast (slightly slower) |
| Use for security? | Never | Yes |
| Uniform distribution? | Approximately | Yes |
| Browser support | All browsers | All modern browsers |
| Use cases | Games, animations | Tokens, keys, fair draws |
What this means for you: This tool gives you the strongest randomness available in a browser. Every number is generated independently with no pattern or seed that could be reverse-engineered.
Common Uses for Random Numbers
Raffles & Prize Draws
Set min/max to your participant range, generate one number, and you've got a fair winner. Enable "no duplicates" for multiple prize tiers.
Dice & Board Games
Set range 1 to 6 for a standard die, 1 to 20 for a D20, or any custom range for your game system. Generate multiple rolls at once for speed.
Sampling & Research
Generate unique random numbers to select participants from a numbered list. No duplicates ensures each selection is distinct.
Testing & Development
Quickly generate test data, random IDs, or seed values for simulations. Batch generation saves time when you need hundreds of values.
Understanding the "No Duplicates" Option
When you enable "no duplicates", the generator produces a set of unique numbers, no repeats. This is essential for things like lottery draws, random sampling, and team assignments where each number should only appear once.
There's one constraint: the count can't exceed the range. If your range is 1 to 10, you can generate at most 10 unique numbers. Asking for 15 unique numbers from a pool of 10 is mathematically impossible, so the generator won't attempt it.
With duplicates allowed (the default), each generation is independent. You might get the same number twice in a row, and that's perfectly valid randomness. Getting 7, 7, 7 is just as random as getting 3, 8, 1.
Worked Random Draw Example
Suppose Priya has 24 numbered entries for a local prize draw and needs three different winners. She sets the minimum to 1, maximum to 24, count to 3, and turns on no duplicates.
Range
1 to 24
Count
3 unique values
Possible result
7, 19, 2
The order is the draw order. If she needs ranked winners, she can treat the first value as first prize, the second as second prize, and the third as third prize.
Common Random Number Mistakes
Requesting more unique values than exist
Ten unique values require a range containing at least ten possible integers.
Expecting no repeats by default
Independent draws can repeat. Turn on no duplicates when a value should only appear once.
Using the result without rules
For public or prize draws, define the entry list, range, and winner order before you generate.
Mixing decimals with integers
This page returns whole numbers. Decide how you want to scale or round if you need decimal values.
Probability Quick Reference
| Scenario | Probability | Odds |
|---|---|---|
| Rolling a 6 on one die | 16.67% | 1 in 6 |
| Flipping heads twice in a row | 25% | 1 in 4 |
| Rolling double sixes | 2.78% | 1 in 36 |
| Picking 1 number from 1-100 | 1% | 1 in 100 |
| Picking 6 from 49 (UK Lotto) | 0.0000072% | 1 in 13,983,816 |
What this means for you: If you're running a raffle with 100 participants, each person has exactly a 1% chance of winning, that's mathematically fair. For multiple prizes, use the "no duplicates" option to ensure the same person can't win twice.
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How to use this tool
Set a minimum and maximum value for your range
Choose how many numbers to generate and whether duplicates are allowed
Click Generate to get cryptographically secure random numbers
Common uses
- Running fair lottery draws and prize raffles
- Rolling dice for tabletop and board games
- Selecting random samples for research or testing
- Generating test data for software development
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Frequently Asked Questions
Is this truly random?
Can I generate multiple numbers?
Are duplicates allowed?
What's the difference between Math.random() and crypto?
Can I use this for a lottery draw?
Is there a limit on the range?
Can I generate negative numbers?
Can I generate decimal numbers?
Is there a maximum count?
Are the results saved?
Can I use this for D&D dice rolls?
Is my data sent to a server?
Results are for general informational purposes only and should be checked before use. They are not professional advice. See our Disclaimer and Terms of Service.