Random Number Generator
Generate one or many random numbers within a specified range — integers or decimals, with or without duplicates.
How to use the Random Number Generator
- Enter your inputs into the Random Number Generator above.
- Results update instantly as you type — no submit button needed.
- Adjust any value to see how the result changes in real time.
How random numbers are generated
Pseudo-random output: x_n = f(x_(n−1)) with a uniform distribution mapped to your range
JavaScript's Math.random() returns a pseudo-random number in [0,1). Scaling to your range: min + Math.random() × (max − min). For integers, round or floor the result.
Worked example
Generate 5 random integers between 1 and 100: e.g., 47, 82, 13, 67, 29 (will differ each time). For decimals between 0 and 1 with 4 places: 0.4729, 0.8156, 0.1342, etc.
Frequently asked questions
Is this truly random?
No — it's pseudo-random, generated by a deterministic algorithm seeded from current state. Good enough for games, sampling, simulations and most applications. Not suitable for cryptography (use crypto.getRandomValues for that).
Can I generate without duplicates?
Yes — the calculator has an option to require unique values. The count of unique values must be ≤ the range size (you can't draw 100 unique integers from 1–50).
Can I set a seed for reproducibility?
Some implementations allow seeding for reproducible sequences — useful for testing. Browser Math.random() does not allow seeding; the calculator may provide a separate seedable mode.