Random Numbers Without Duplicates: Ranges and Sampling Limits
Generate integers within inclusive bounds, understand unique sampling, and learn why Math.random() is unsuitable for security-sensitive values.
Use the related XKit tool
Open Random Number GeneratorXKit's random number generator selects integers between a minimum and maximum, including both endpoints. You can allow repeated values or request a sample without duplicates. It uses Math.random(), so the results are pseudorandom rather than cryptographically secure.
Calculate how many distinct values are available
An inclusive integer range contains maximum − minimum + 1 values. The range 1 to 10 contains 10 distinct integers; the range −2 to 2 contains five.
Without duplicates, the requested count cannot exceed the number of available integers. Asking for six unique numbers from −2 to 2 is impossible, regardless of how many times a generator runs.
Duplicates allowed versus sampling without replacement
When duplicates are allowed, the same integer may appear more than once. A five-number result from 1 to 10 might include two copies of 7.
Without duplicates, each selected integer appears at most once. This is useful for choosing distinct sample positions or classroom exercises, but it does not turn the generator into a secure or independently verifiable draw.
Check the result before using it
Set the integer bounds, choose the count, and decide whether repeats are acceptable before generating. Check that every result is inside the inclusive range and that unique mode returns no repeated integers.
Do not use this tool to create passwords, authentication codes, or keys. Predictability matters for security, and Math.random() is not designed for that purpose. Generating lottery numbers also does not improve the chance of winning.
Sources and technical references
Frequently Asked Questions
Are the minimum and maximum included?
Yes. Both integer bounds are included, so the number of possible distinct values is maximum minus minimum plus one.
Can this generator create secure passwords?
No. It uses Math.random(), which is not cryptographically secure. Use a generator designed for password creation instead.