Random Number Generator
Generate one or many random numbers in any range, with or without duplicates.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this random number generator
- Enter a Min and Max value to define your integer range.
- Set Count to how many numbers you want (1–100).
- Uncheck "Allow duplicates" if every number must appear only once.
- Press Generate to see your random numbers in the result panel.
- Use Copy all to copy the numbers, or Reset to clear everything.
About this random number generator
The random number generator produces one or more random integers within a range you define, instantly and without any server request. You control the minimum value, the maximum value, and how many numbers to generate at once — up to 100 per click.
When duplicates are allowed, each number is drawn independently using JavaScript's Math.random(), scaled to your range with the formula: Math.floor(Math.random() × (max − min + 1)) + min. When duplicates are disabled, the tool builds a pool of every integer in your range and shuffles it using the Fisher-Yates algorithm, then takes the first Count items — guaranteeing a unique set with no repeats.
For example, setting Min to 1, Max to 49, Count to 6, and disabling duplicates produces six distinct lottery-style numbers such as 3, 17, 22, 31, 38, 44. The same setup with duplicates allowed could return repeated values. A running history panel keeps the last ten generations on screen for easy comparison.
This tool is useful for lotteries, board games, classroom activities, statistical sampling, and any situation where unbiased integer selection is needed.
FAQ
- What is a random number generator and how does this one work?
- A random number generator picks numbers without a predictable pattern. This tool uses Math.random() — the browser's built-in pseudorandom number source — scaled to your chosen range, so results are statistically uniform across all integers from Min to Max.
- What formula does the random number generator use?
- For each number with duplicates allowed: Math.floor(Math.random() × (max − min + 1)) + min. When duplicates are off, it shuffles the full pool using the Fisher-Yates algorithm and slices off the first Count values.
- What happens if I set Count higher than the range with duplicates off?
- The tool shows an error explaining that there are not enough unique integers in the range. For example, asking for 10 unique numbers in the range 1–5 is impossible, so you must either widen the range, lower Count, or re-enable duplicates.
- How accurate or truly random are the results?
- The tool relies on Math.random(), a pseudorandom number generator built into every modern browser. Results are suitable for games, sampling, and everyday decisions, but not for cryptographic or security-critical purposes.
- Does the random number generator store my inputs or results?
- No. The random number generator runs entirely in your browser; nothing is sent to a server. Closing or refreshing the page clears all inputs and history.
- Is the random number generator free?
- Yes, it is completely free with no signup, no account, and no usage limit.