Generate random integers or decimals in your chosen range, with options for repeats, sorting, endpoint rules, and repeatable seeded results.
Advanced options
How to use our Random Number Generator Calculator
- Choose Number type as Integers or Decimals.
- Enter Minimum value and Maximum value for the range you want.
- Enter How many numbers as a positive whole number.
- Choose Allow repeats. Pick No if every result must be different.
- Open Advanced options if needed. Use Decimal places for decimal mode, choose Include endpoints, and set Sort results.
- Turn Seed mode on only if you want the same sequence again later, then enter a Seed value.
- Click Calculate to generate your numbers.
- Sanity-check the output: compare How many numbers with Possible values in range and read Unique draw status to make sure your settings can produce unique results.
Definitions
Number type: Chooses whether results are whole numbers (integers) or numbers with digits after the decimal point.
Minimum value: The smallest value allowed in the range.
Maximum value: The largest value allowed in the range.
How many numbers: The number of random values to generate in one run.
Allow repeats: If Yes, the same value can appear more than once. If No, every result must be different.
Decimal places: In decimal mode, how many digits appear after the decimal point.
Include endpoints: Decides whether the minimum, maximum, both, or neither can be selected.
Possible values in range: The count of distinct values available under the current rules.
Unique draw status: A quick check showing whether your request can be completed without repeats.
Seed mode: An optional repeatable setup where the same seed and settings produce the same sequence again on this implementation.
Sequence note: A short message that tells you whether the current run is seeded and reproducible or unseeded and ordinary.
Pseudo-random: Algorithm-based randomness that is suitable for everyday picks and classroom use, but it is not the same as true physical randomness.
Common mistakes and quick fixes
Mistake: Entering a Minimum value that is greater than Maximum value .
Fix: Swap the two values so the minimum is smaller than or equal to the maximum.
Mistake: Typing 3.5 in How many numbers .
Fix: Use a positive whole number such as 1, 5, or 20.
Mistake: Choosing Allow repeats as No, then asking for more values than the Possible values in range allows.
Fix: Lower How many numbers , widen the range, or switch Allow repeats to Yes.
Mistake: Using decimal values in integer mode under Number type .
Fix: Either switch Number type to Decimals or change Minimum value and Maximum value to whole numbers.
Mistake: Setting Include endpoints to exclude one or both ends without noticing that no values remain.
Fix: Check Possible values in range . If it is zero or invalid, include more endpoints or widen the range.
Mistake: Expecting the same output again while Seed mode is Off.
Fix: Turn Seed mode On and reuse the exact same Seed value and settings.
Limitations & Key Assumptions / Boundary Conditions
- This tool is designed for general-purpose random picking, classroom examples, and simple simulations. It should not be used for passwords, secrets, or regulated gaming outcomes.
- Most browser-based random generation is pseudo-random, meaning it is created by an algorithm rather than a physical random process.
- Seeded results are reproducible only when the same settings and the same Seed value are used on this page implementation. Different sites or algorithms can give different seeded sequences.
- In decimal mode, values are generated from a fixed grid based on Decimal places, so the tool samples visible decimal steps rather than every possible real number between the limits.
- If Allow repeats is No, the request must fit inside the Possible values in range. Otherwise the calculator correctly returns an error instead of partial output.
- Endpoint rules can remove all available values when the range is too narrow, especially when Minimum value equals Maximum value or decimals use a coarse grid.
Methodology
How the calculator counts possible values
First, the calculator validates the range and your request size. Minimum value must be less than or equal to Maximum value, and How many numbers must be a positive whole number.
N = max - min + 1
That formula is used for integer mode when both endpoints are included. Here, N means the number of distinct integers that can be drawn.
N = (max - min + 1) - I(exclude min) - I(exclude max)
For integer mode with endpoint exclusions, the calculator subtracts 1 for each excluded end. If the final count is 0 or less, the range is invalid.
Decimal mode on a visible grid
In decimal mode, the calculator does not treat the range as infinitely detailed. It builds a discrete grid so the random values match the number of shown decimal places.
step = 10^(-p)
Here, p is Decimal places. For example, if Decimal places is 2, the grid step is 0.01.
N = floor((max - min)/step) + endpoint_adjustment
In practice, the calculator counts the allowed grid points after applying the selected endpoint rule. This makes Possible values in range clear and makes no-repeat checking well-defined.
Unique draw check
feasible = (repeats = yes) OR (count <= N)
If Allow repeats is Yes, any positive count is feasible. If repeats are not allowed, How many numbers must be less than or equal to the number of distinct allowed values. If not, the calculator shows an error and does not generate partial results.
How numbers are generated
Unseeded mode uses the page's normal pseudo-random process for everyday use. Seeded mode converts your Seed value into a repeatable starting state so the same settings produce the same sequence again on this implementation [1][2]. The page still uses algorithm-based pseudo-random generation, so it is not a cryptographic or regulated-gaming tool [3].
Sorting and display
Numbers are first generated in draw order. After that, the calculator either keeps that order or sorts the final list ascending or descending, depending on Sort results.
Mini example
Suppose you choose integer mode with Minimum value = 1, Maximum value = 5, Allow repeats = No, and Include endpoints = Exclude both min and max.
N = (5 - 1 + 1) - 1 - 1 = 3
The allowed integers are 2, 3, and 4, so Possible values in range is 3. If How many numbers is also 3, the request is feasible. If you ask for 4 unique values, it is impossible and the calculator returns an error.
Assumptions used
The calculator assumes integer mode uses whole-number bounds, decimal mode uses a fixed precision grid, hidden optional fields do not affect the result, and seeded reproducibility applies only when every visible setting matches exactly.