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Random Number Generator

Generate cryptographically secure random numbers using Web Crypto API with custom min/max ranges, count, and no-repeats option. Supports integer and decimal modes, formatted output, and history. Essential for lottery picks, game dice, sampling, lottery, and decision-making.

Generators

🎲

Random Number Generator

Set the range and count, then generate random numbers.

🔒No upload to servers
⚡100% client-side
🆓Free forever

In brief

Generate cryptographically secure random numbers using Web Crypto API with custom min/max ranges, count, and no-repeats option. Supports integer and decimal modes, formatted output, and history. Essential for lottery picks, game dice, sampling, lottery, and decision-making.

Reviewed: 2026-09-18

What this tool supports

  • Cryptographically secure generation via the Web Crypto API
  • Custom minimum and maximum bounds for every draw
  • Single, multiple, and copy-ready list output modes
  • Optional no-repeat mode for sampling without replacement
  • Integer and decimal modes with controlled precision
  • Distribution view that reflects exactly the draws performed
  • Recent-history log with clearable local storage
  • Runs entirely in the browser with no account or upload

How to use Random Number Generator

Follow this step-by-step guide to use Random Number Generator effectively.

  • Step 1

    Enter your values

    Input the required values into the provided fields.

  • Step 2

    Select options

    Choose any available options or modes to customize the calculation.

  • Step 3

    Click Calculate

    Press the Calculate button to process your input.

  • Step 4

    Review the result

    Examine the calculated result displayed in the output panel.

  • Step 5

    Copy or share

    Use the copy button to save the result to your clipboard.

Common mistakes

Assuming equal distribution in very small ranges

Consequence: Random number generators may show apparent clustering in small sample sizes.

Fix: Generate many numbers to see the true distribution. Short sequences naturally appear non-random.

Using random numbers for cryptographic purposes

Consequence: Browser Math.random() is not cryptographically secure and should not be used for keys or tokens.

Fix: Use the Web Crypto API's getRandomValues() for security-sensitive applications.

Expecting truly unique numbers without checking for repeats

Consequence: Random generation can produce the same number twice, especially in small ranges.

Fix: Use the no-repeat option if available, or generate more numbers than needed and deduplicate.

Assuming equal distribution in small ranges

Consequence: Random generators may show apparent clustering in short sequences.

Fix: Generate many numbers to see the true distribution. Short sequences are not statistically representative.

Best practices

  • Match the output mode to the use case: single for one-off draws, list for downstream pasting.
  • Set no-repeat only when sampling without replacement is intended; repeated draws otherwise stay independent.
  • Keep bounds inclusive and verify that the range contains enough values for the requested count in no-repeat mode.
  • Review the distribution view after large batches to confirm uniform coverage of the requested range.

Connected workflows

Calculate and review

Random Number Generator

Set the minimum and maximum bounds with the draw count and optional no-repeat rule to produce cryptographically secure integers or decimals, with a distribution view and recent-history log.

  1. Enter values
  2. Review result
  3. Copy output

Browser limitations

  • The generator uses cryptographically secure randomness, which is slower than basic random number generation for very large batches.
  • Generating large ranges or many numbers at once may take a moment to display.
  • Random numbers are generated using the browser's crypto.getRandomValues() API for cryptographic-quality randomness.

Authoritative resources

Math is FunPublisher: mathsisfun.com · Reviewed: 2026-09-18

Concrete examples

Input
Sample input values
Result
Sample result

This example demonstrates Random Number Generator processing.

Frequently asked questions

How do I generate a random number?

Set your minimum and maximum values, choose how many numbers to generate, and click Generate. The tool uses cryptographically secure randomness.

What does "no repeats" mean?

When enabled, each generated number is unique within the batch. No number will appear twice in the same generation.

Is this truly random?

Yes. The tool uses crypto.getRandomValues() for cryptographic security, falling back to Math.random() only when unavailable.

Can I generate decimal numbers?

Yes. Switch to decimal mode to generate random numbers with custom decimal places within your range.

Does this tool store my generated numbers?

No. All generation happens locally in your browser. No data is transmitted or stored.

How random are the generated numbers?

The tool uses the browser Math.random() which is suitable for general purposes.

Can I generate numbers without repeats?

Yes, enable the no-repeat option to ensure all generated numbers are unique.

What is the maximum count I can generate?

You can generate up to 1000 numbers at once.

Privacy and offline behavior

Random Number Generator processes all input and output locally in your browser. No data is uploaded, stored, or transmitted.