Probability of a given number
P = 1 ÷ n, with n = max − min + 1
n is the number of integers in the range, limits included.
Random number generator (draws, dice, lottery)
Random number generator: minimum and maximum, quantity up to 1,000, integers or decimals, draws without repeats. Randomness from the browser's Web Crypto API, handy for raffles, dice, lottery picks and sampling.
- Clipboard
Generation settings
Quick ranges
Generation options
123
1×
Result
Was this tool useful?
How does this tool work?
Choose a range, a quantity and a type of value, and the tool draws the numbers at once. Use it for a raffle among numbered participants, a dice roll, lottery picks, a sample from a numbered list or test data. Draws without repetition (unique values) are supported too.
You set a minimum, a strictly greater maximum and a quantity from 1 to 1,000. In integer mode every number is drawn with equal probability among the integers of the range, limits included: between 1 and 6, each face has a 1 in 6 chance. In decimal mode the value is drawn uniformly in the real interval, with the full precision of a floating-point number.
Randomness comes from the browser's Web Crypto API (crypto.getRandomValues), a cryptographic-quality generator, not from Math.random, which can be predictable. The 53 random bits it supplies are used to build a uniform number between 0 and 1; mapped onto a range of n integers, the leftover bias stays below n ÷ 2^53, negligible in practice.
With "unique values", a number already drawn is discarded: this is drawing without replacement, like lottery balls. The range must then hold at least as many integers as values requested (from 1 to 5 you cannot draw 6 unique values). Without it, repeats are possible: in 100 draws between 1 and 100, the chance that a given number appears at least once is about 63.4%.
A cryptographic draw is not a password generator: values are shown on screen and copied in plain text. For a secret, use the password generator. For a fair raffle, make sure each participant has one unique number in the range.
How to use this tool
Set the limits
Minimum and maximum, with the maximum greater than the minimum. For a six-sided die: 1 and 6; for a 49-number lottery: 1 and 49.
Set quantity and type
From 1 to 1,000 values, integers or decimals. Turn on unique values for a draw without replacement.
Generate and copy
Each click draws a fresh set. If the range is too small for unique values, a message says so.
Probabilities in a random draw
For n equally likely values, every value has the same chance.
Combinations of k unique values
C(n, k) = n! ÷ (k! × (n − k)!)
Number of different draws of k numbers from n, ignoring order.
At least one appearance in k draws with replacement
P = 1 − (1 − 1 ÷ n)^k
Probability that a given number comes up at least once.
- n
- number of possible values in the range
- k
- number of draws or requested values
- P
- probability (between 0 and 1)
Example: in a 6-from-49 lottery, C(49, 6) = 13,983,816 combinations, so one chance in 13,983,816. To get at least one 6 in 4 die rolls, P = 1 − (5 ÷ 6)^4 ≈ 51.77%.
Use cases
Raffles
Pick a winner or a speaking order among numbered participants, without visible bias.
Games and dice
Replace a die, a coin (1 or 2) or a lottery slip for a game or practice.
Sampling
Pick random rows from a numbered file for a quality check or an audit.
Tests and simulations
Produce test values, dummy IDs or draws for a simple simulation.
Examples
Rolling a die
Each face is equally likely: 1 in 6, about 16.67%.
Input
min 1, max 6, quantity 1, integersResult
one integer from 1 to 66-from-49 lottery ticket
There are 13,983,816 ways to choose 6 numbers from 49, so one chance in 13,983,816 of matching the draw.
Input
min 1, max 49, quantity 6, integers, uniqueResult
6 distinct numbers between 1 and 49Raffle with 3 winners
With 100 numbered participants, nobody can be drawn twice.
Input
min 1, max 100, quantity 3, integers, uniqueResult
3 different participant numbersDecimal test data
Useful to simulate probabilities or fill a dummy dataset.
Input
min 0, max 1, quantity 5, decimalsResult
5 decimal numbers between 0 and 1Range too small
Only 5 integers exist, so 6 distinct ones cannot be drawn.
Input
min 1, max 5, quantity 6, uniqueResult
error messageTips and best practices
- For a coin, draw 1 or 2; for a die, 1 to 6; for a percentage, 1 to 100.
- With two dice, draw two values from 1 to 6: their sum is not uniform (7 is the most common).
- Number every participant before the raffle and keep the list so you can justify the result.
- For unique values, the quantity must not exceed the number of integers in the range.
- For passwords or keys, prefer a dedicated generator.
Sources and references
- W3C, Web Cryptography API (opens in a new tab), World Wide Web Consortium, 2017Page in English
Frequently asked questions
Are the numbers truly random?
They come from the browser's cryptographic generator (crypto.getRandomValues), unpredictable in practice, with 53 bits of precision. It is not a physical draw, but it is better than Math.random.
What is the probability of drawing a specific number?
It is 1 ÷ n, where n is the number of integers in the range: 1 in 100 (1%) between 1 and 100, 1 in 6 (16.67%) for a die.
How do I draw without duplicates?
Turn on "Unique values". The range must hold at least as many integers as values requested, or an error message appears.
How many numbers can I generate at once?
Up to 1,000 per draw. Larger quantities are capped at 1,000.
Can I draw decimal numbers?
Yes: turn off the integers option. Values are spread uniformly between the two limits.
Related tools
Keep going with these tools
Tools similar or complementary to this one.
Similar tools
Generate strong random passwords from 8 to 128 characters, with the entropy shown.
Mathematics & calculationFeaturedUse this tool
Generate one or more random UUID v4 identifiers instantly and copy them when needed.
Mathematics & calculationFeaturedUse this tool
Create brand, product, project or domain names from your keywords – not personal names.
Mathematics & calculationUse this tool