What does the random number generator do?
Generates random integers or decimals within a custom min/max range. Supports multiple values at once and unique (no-duplicate) sets — all in your browser.
Create random numbers for testing and simulations.
The Random Number Generator is a versatile tool for creating random integers within any specified range. It supports generating single or multiple random numbers, with options for unique numbers and duplicate handling. Perfect for testing, simulations, games, sampling, and any scenario requiring random numeric values.
A random number generator (RNG) produces numbers that have no predictable pattern. Browser-based tools use Math.random() or the Web Crypto API (crypto.getRandomValues) to generate integers or decimals within a specified range.
Random number generators fall into two broad categories:
**Pseudorandom number generators (PRNG)**: Use a deterministic algorithm with a seed value. Given the same seed, they produce the same sequence — not truly random, but statistically unpredictable for practical purposes. JavaScript's Math.random() is a PRNG.
**Cryptographically secure PRNGs (CSPRNG)**: Use additional entropy sources (hardware events, system entropy) to ensure outputs cannot be predicted even with knowledge of the algorithm. The Web Crypto API's crypto.getRandomValues() is cryptographically secure and available in all modern browsers.
For everyday use cases — games, simulations, testing, random selection — Math.random() is sufficient. For security-critical applications (token generation, password creation, lotteries), a CSPRNG is required.
This tool generates:
Concise answers for common searches — definitions, steps, and comparisons.
Generates random integers or decimals within a custom min/max range. Supports multiple values at once and unique (no-duplicate) sets — all in your browser.
Yes — numbers are generated locally in your browser. Range settings and results are not uploaded to EverydayTools servers.
Enter the lower and upper bounds of your range. The range can include negative numbers (e.g., min: -100, max: 100). For a standard 1–100 range, enter 1 and 100.
Choose how many random numbers to generate. If duplicates are disabled, the count cannot exceed the range size (max − min + 1) — the tool will show a warning if you request more than is possible.
Integer mode generates whole numbers. Decimal mode generates floating-point numbers — set the number of decimal places (1–6) for the precision you need.
Numbers appear immediately. Click Copy to copy all results to the clipboard, or Generate again for a fresh set.
Input
Min: 1 · Max: 49 · Quantity: 5 · Duplicates: offOutput
e.g. 7, 15, 23, 38, 44With duplicates disabled, each number is drawn once — like balls in a lottery drum. The count (5) must be ≤ range size (49), which it is.
Input
Min: 0 · Max: 1 · Quantity: 1 · Decimal: 4 placesOutput
e.g. 0.7341A uniform random float between 0 and 1 is the foundation of most probability simulations — compare against a threshold (e.g., 0.7 = 70% probability event).
Common real-world scenarios where this tool saves time.
Generate random integers for test data, boundary value analysis, fuzz testing inputs, or populating seed data in development databases.
Roll dice (1–6), draw random cards, set random spawn positions, or generate simulation parameters without writing code.
Pick a random winner from entries (1–N where N is the number of entries), randomly assign tasks, or sample a subset from a numbered list.
Demonstrate probability concepts by generating large samples — count occurrences of each value and observe how distributions converge with larger N.
Demonstrate random number concepts in educational settings. For production key material, use a dedicated cryptographic library — not a browser generator.
Step-by-step chains that connect related tools for common tasks.
Use random numbers to populate test inputs for software testing.
Pick a winner from numbered entries without bias.
The two main random number APIs in browsers — choosing the right one for your use case.
| Feature | Math.random() | crypto.getRandomValues() |
|---|---|---|
| Type | PRNG (pseudorandom) | CSPRNG (cryptographically secure) |
| Speed | Very fast | Slightly slower |
| Predictability | Statistically unpredictable | Cryptographically unpredictable |
| Use case | Games, simulations, testing | Passwords, tokens, security keys |
| Browser support | All browsers | All modern browsers |
| Suitable for security | No | Yes (for most applications) |
This tool uses Math.random() for general use. Use crypto.getRandomValues() (via the password generator) when generating security credentials.
Which randomness approach matches different needs.
| Use case | Security requirement | Recommended approach |
|---|---|---|
| Dice roll / game | Low | Math.random() ✓ |
| Test data generation | Low | Math.random() ✓ |
| Random survey sample | Low–Medium | Math.random() ✓ |
| Temporary password / token | High | crypto.getRandomValues() |
| Cryptographic key material | Very high | Dedicated crypto library |
| Regulated lottery / gambling | Certified | Hardware RNG + audit |
Never use browser Math.random() for security credentials — use a cryptographic random source.
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The tool uses Math.random(), which is a pseudorandom number generator (PRNG) seeded from system entropy. It is statistically unpredictable for practical use but not cryptographically secure. For security-critical applications, use crypto.getRandomValues() — available via dedicated password generators or security-focused tools.
Yes — disable the 'Allow duplicates' option. The tool then draws numbers without replacement, like a lottery draw. The count you request cannot exceed the number of unique values in the range (max − min + 1). For example, generating 10 unique numbers from the range 1–5 is impossible and will produce a warning.
The tool supports any range where min and max are valid JavaScript numbers (up to ±2^53 − 1, or approximately ±9 quadrillion). Practically, ranges of millions to billions work fine for generating integers or decimals.
Yes. Set a negative minimum value, such as min: −100 and max: 100. The generator will produce numbers anywhere in that range, including negative values.
A random number generator produces numbers within a specified numeric range (e.g., 1–100). A UUID generator produces 128-bit universally unique identifiers in hex format (e.g., 550e8400-e29b-41d4-a716-446655440000), designed for use as database keys, session IDs, and distributed system identifiers — not numeric values.
For informal raffles or office draws, yes — the unpredictability is sufficient. For regulated lotteries, legal gambling, or prize draws with financial stakes, use certified random number hardware or a notarized randomness service, as these require verifiable and auditable randomness.
Decimal mode generates floating-point numbers. Precision sets how many decimal places appear in the result: 1 decimal = X.X, 2 decimals = X.XX, 3 = X.XXX, etc. For example, a range 0–1 with precision 4 might generate 0.7423.
Yes — all random number generation runs locally in your browser. The range, quantity, and generated values are not sent to EverydayTools servers.
All random number generation runs in your browser. Range inputs and generated values are not sent to EverydayTools servers.
Not suitable for cryptographic key material, regulated lotteries, or gambling applications requiring certified randomness.
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Reviewed by EverydayTools Editorial Team on 2026-06-08.