How to use the random 4 digit number generator
- Set How many numbers to a value between 1 and 100.
- Check Allow leading zeros if you need codes from 0000 to 9999 instead of 1000 to 9999.
- Check All numbers must be unique to prevent any duplicates in the output.
- Pick a Sort order or leave it as No sorting for raw random order.
- Click Generate to see your list of random four digit numbers.
How the random selection works
The generator uses the Web Crypto API (crypto.getRandomValues) to produce cryptographically strong random integers. When leading zeros are off, each draw picks a value from 1000 to 9999, giving 9000 possible outcomes. With leading zeros on, the range expands to 0000 through 9999 for 10000 outcomes.
If uniqueness is required, the tool tracks every number already drawn and re-rolls until a fresh value appears. Sorting happens after all draws are complete, using a standard numeric comparison so that 0042 correctly sorts before 1000.
Probability of a repeated 4-digit code
A common question is how likely two random four digit numbers are to match. With 10000 possible codes (0000 to 9999), the chance that any single new draw matches one specific previous draw is 1 in 10000, or 0.01 percent.
However, when generating multiple numbers the birthday problem applies. The probability that at least two numbers in a set of n share the same value is approximately 1 - e^(-n(n-1) / 20000). For 10 numbers in a pool of 10,000 (leading zeros allowed) this is about 0.45 percent. For 100 numbers it rises to about 39 percent. With the default 1000 to 9999 pool of 9,000 values, 100 numbers collide with probability 42.4 percent. That is why the unique option exists: it guarantees no collisions regardless of count.
Common uses for 4-digit numbers
Four digit codes appear everywhere in daily systems:
- PIN codes for bank cards, phone locks and door entry pads.
- Verification codes sent by SMS or email for two-factor authentication.
- Lottery and raffle tickets where a short numeric identifier is needed.
- Test data for software developers populating forms or databases.
- Game mechanics such as combination locks in puzzles or tabletop RPGs.
For other lengths, see the random 3 digit number generator or the random 5 digit number generator.
Security warning about PINs
This random 4 digit number generator is built for convenience, testing and entertainment. It should not be your sole method for creating security-critical PINs such as bank card codes or device unlock patterns. While the underlying randomness source is strong, human habits like writing down generated lists or reusing them across services introduce risk.
For high-security needs, use a dedicated hardware token or a vetted password manager. If you need longer or more complex secrets, try the password generator or the UUID generator instead.
Reference table of ranges
The table below shows the exact range and total pool size depending on the leading zero setting.
| Setting | Minimum | Maximum | Total possibilities |
|---|---|---|---|
| Leading zeros off | 1000 | 9999 | 9000 |
| Leading zeros on | 0000 | 9999 | 10000 |
When uniqueness is enabled, the maximum count you can request is limited by the pool size. The tool enforces a hard cap of 100 numbers per generation, which fits comfortably within both pools.
Worked examples
| Example | Input | Result |
|---|---|---|
| Single number | How many numbers: 1; Allow leading zeros (0000 to 9999): no; All numbers must be unique: no; Sort order: none | 9097 |
| Ten unique sorted numbers | How many numbers: 10; Allow leading zeros (0000 to 9999): no; All numbers must be unique: yes; Sort order: asc | 1787, 5428, 6999, 7086, 7780, 7986, 8814, 8868, 9749, 9780 |
| Five PIN-style codes with leading zeros | How many numbers: 5; Allow leading zeros (0000 to 9999): yes; All numbers must be unique: no; Sort order: none | 3571, 3604, 6094, 0335, 1308 |
FAQ
What range does this random 4 digit number generator use?
By default it generates numbers from 1000 to 9999. If you enable the leading zeros option, the range becomes 0000 to 9999.
Can I get duplicate numbers?
Yes, unless you check the unique box. Without that option each draw is independent, so repeats are possible especially when generating many numbers.
Is it safe to use these numbers as PINs?
The randomness source is strong, but you should not rely on any web tool alone for critical security PINs. Use a dedicated hardware or software credential manager for banking and device locks.
How many numbers can I generate at once?
You can generate between 1 and 100 numbers per click. The limit keeps the output readable and ensures the unique option always has enough values to draw from.
Does this tool send my numbers to a server?
No. All generation happens locally in your browser using JavaScript. Nothing is uploaded or stored.
Why do some results start with zero?
That only happens when the leading zeros checkbox is ticked. The number is formatted as a four-character string so 42 displays as 0042.