Random Number Generator
Generate one or more cryptographically secure random integers within a minimum/maximum range, with or without duplicates.
Calculator Inputs
- Generated numbers
- Result not available yet
- Count
- Result not available yet
- Range
- Result not available yet
About these results
CalcSpectrum calculators produce automated estimates using established formulas and the specific values you enter. Because real-world outcomes depend on input accuracy, mathematical assumptions, and rounding conventions, please verify critical figures with an appropriately qualified financial, tax, medical, legal, or other professional, as relevant.
How It's Calculated
Formula
This generator draws each integer independently and uniformly from the inclusive [minimum, maximum] range, using the browser's cryptographically secure random number generator (Web Crypto's crypto.getRandomValues) with unbiased rejection sampling — never Math.random. With duplicates allowed, each number is drawn independently, so the same value can appear more than once. With duplicates disabled, numbers are drawn without replacement (a virtual partial Fisher-Yates selection), so quantity cannot exceed the number of distinct integers in the range. This version generates whole numbers only.
Worked Examples
5 unique numbers between 1 and 49 (e.g. a lottery-style draw)
- Set minimum = 1, maximum = 49, quantity = 5, allow duplicates = off.
- Click Generate Numbers.
- 5 distinct integers are drawn without replacement from {1, ..., 49}.
Frequently Asked Questions
Can I generate decimal or floating-point random numbers?
Not in this version. This generator currently produces whole (integer) numbers only.
What happens if I disable duplicates and ask for too many numbers?
Generation is rejected if the requested quantity exceeds the number of distinct integers available in [minimum, maximum] — for example, asking for 10 unique numbers between 1 and 5 is impossible.
Does changing the range reroll my results?
No. Numbers are generated only when you click "Generate Numbers." Changing the range, quantity, or duplicates setting afterward does not change the displayed numbers until you click the button again.