Random Serial Number Generator
Generate serial numbers with your own prefix, length and character set, all unique in the batch.
Random Serial Number Generator
4 groups of 4
How many serials
Format
How to use the serial generator
- Set the groups and characters per group, such as 4 by 4 for a classic key.
- Choose letters and digits, letters only or digits only, and the joining style.
- Generate a batch and export it as a CSV for your records.
About Random Nr's Serial Number Generator
The serial number generator builds serial numbers from your own prefix, length and character set, all unique within the batch. Set the pattern you want and how many you need, and Random Nr generates a run with no repeats, which suits seeding product records, mocking up licence keys or filling a demo with believable references.
How many serial numbers are possible
Serials here draw from 34 characters, the digits plus the alphabet with the confusable I and O removed. The space grows exponentially with length:
| Serial length | Possible serials |
|---|---|
| 8 characters | about 1.8 trillion |
| 12 characters | about 2 quintillion |
| 16 characters | about 3.2 septillion |
A 16 character key of this kind carries roughly 81 bits of randomness, far beyond anything guessable, which is why the classic 4 by 4 grouped format became the industry habit for licence keys.
Will two serials ever collide
Independent random serials can repeat in principle, and the birthday rule says the risk grows with the square of the batch. In practice the space is so large it does not matter: even a million 12 character serials carry a collision chance around one in a billion. For guaranteed uniqueness at small scale, sequential schemes from the invoice or ticket generators are the alternative; for anything cryptographic, use a dedicated secrets library rather than a visible serial.
Why serial numbers are easy to read
Excluding I and O keeps 0 and 1 unambiguous when a serial is read over the phone or typed from a label, a lesson learned by every support desk. The dash, space or plain joining styles cover print, databases and CSV imports. Pair the serials with the barcode generator when the product also needs a scannable retail code.
More code and ID generators
Frequently asked questions
Can I set the format
Yes. Choose the number of groups and characters per group, so 4 by 4 gives a key like AAAA-BBBB-CCCC-DDDD, and other shapes are a click away.
Can I use digits only or letters only
Yes. Switch between letters and digits, letters only, or digits only to match the style you need.
Are confusing characters removed
Yes. The letters exclude I and O so serials are not misread as 1 or 0.
Are they unique
Each serial is generated independently at random. For a small batch repeats are very unlikely, though not impossible.
Is it free
Yes, free and with no sign up.
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For invoice references use the invoice number generator, or a product barcode with the barcode number generator.