Random Number Generator with Custom Range
This random number generator picks numbers within any range you define — from a simple 1 to 10 draw to large ranges with millions of possibilities. You can generate a single number or a whole list, choose between integers and decimals, allow or block duplicates, and sort the results. Everything runs instantly in your browser, so no data is sent anywhere.
Random numbers are the backbone of raffles, giveaways, games, statistical sampling, and testing. The generator uses the pseudorandom algorithm built into your browser, which produces a uniform distribution: every number in the range has the same chance of being drawn. For casual draws, classroom activities, and simulations this is more than enough; for cryptographic purposes, dedicated secure generators should be used instead.
How it works
Integer draw: n = min + floor(random() × (max − min + 1)), where random() returns a uniform value in [0, 1). For unique draws, the range is shuffled with the Fisher–Yates algorithm and the first k values are taken.
Use cases
- Drawing a winner for a raffle or giveaway from numbered tickets
- Picking random students or team members without bias
- Generating lottery-style number sets with no duplicates
- Creating random test data for spreadsheets and software testing
- Selecting a random sample for a survey or statistics exercise
- Settling decisions fairly when a coin flip is not enough options
Frequently asked questions
How does a random number generator work?
The generator uses your browser's pseudorandom algorithm, which produces a sequence of values that behaves statistically like true randomness. Each value in [0, 1) is scaled to your range with the formula min + floor(random() × (max − min + 1)). The result is a uniform distribution, meaning every number in the range has an equal probability of being drawn.
Are the numbers truly random?
They are pseudorandom: generated by a deterministic algorithm seeded with unpredictable system data. For raffles, games, sampling, and everyday decisions the results are indistinguishable from true randomness. Only cryptographic applications, such as generating encryption keys, require hardware-based or cryptographically secure generators.
How do I generate random numbers without repeats?
Enable the unique values option. Instead of drawing independently each time, the tool shuffles all numbers in the range using the Fisher–Yates algorithm and takes the first ones from the shuffled list. This guarantees no duplicates, which is essential for raffles where each ticket can only win once. Note that the amount of numbers requested cannot exceed the size of the range.
Can I use this generator for a raffle or giveaway?
Yes, that is one of its most common uses. Set the minimum to 1 and the maximum to the number of participants or tickets, enable unique values if you need several winners, and generate. Because every number has the same probability, the draw is fair. For transparency, many organizers generate the numbers live in front of the audience or record the screen.
What is the difference between generating integers and decimals?
Integers are whole numbers such as 7 or 42, which suit raffles, dice-style draws, and picking positions in a list. Decimals include fractional values such as 3.72 and are useful for simulations, generating test data, and scientific sampling. In decimal mode you can also control how many decimal places the results should have.