Random ZIP Code
10012
- New York
- State
- 100
- Prefix
- NY
- Prefix belongs to
These are invented, not looked up
The first three digits come from the real prefix range assigned to that state, so the code is plausible and in the right place. The last two are random, so the full code may not be a delivery area. For test data that is the point; for anything real, check it against the USPS lookup.
ZIP codes here are generated for test data. The first three digits are drawn from the range the USPS actually assigns to the state you pick, so the code is plausible and lands in the right part of the country; the last two are invented, so the full code may not be a real delivery area.
How it works
A ZIP code is five digits with real structure. The first digit covers a group of states running roughly west from the north-east: 0 for New England, 9 for the Pacific coast. The first three together identify a sectional centre facility, the sorting hub that serves an area. The last two narrow it to a post office or delivery zone.
- Each state's prefix range is the real allocation. New York runs 100 to 149, California 900 to 961, Texas 750 to 799.
- The last two digits are drawn at random from 00 to 99, which is why the result is plausible rather than verified.
- Selecting a state restricts the prefix to that state's range; selecting any state draws from all 50.
- Up to 100 codes can be generated at once for filling a test dataset.
The reason to generate rather than copy a real ZIP code is that test data containing real addresses tends to escape into emails, invoices and support tickets. A code that is structurally correct exercises the same validation without pointing at a real place.
Examples
A New York code
State
New York
Result
A code beginning 100 to 149
The prefix genuinely belongs to New York, so a lookup that only validates the prefix will accept it as being in the right state.
The first digit
State
Maine against California
Result
039–049 against 900–961
ZIP codes were allocated geographically, starting at 0 in the north-east and running to 9 on the west coast.
Bulk test data
How many
100
Result
A hundred codes across all 50 states
Enough to populate a test table without any of them being a real customer address.
Frequently asked questions
Are these real ZIP codes?
The first three digits are, that prefix is genuinely assigned to the state shown. The last two are random, so the complete five-digit code may not correspond to a delivery area. It is designed to be structurally valid test data, not a lookup.
Will a generated ZIP survive a validation check?
It depends what is validating. Format checks and state-prefix checks will pass. Anything that queries the USPS database or checks the code against a city will fail for some results, because the last two digits are invented.
What do the five digits actually mean?
The first digit is a group of states, allocated west from the north-east. The first three identify the sectional centre facility that sorts for that area. The last two narrow it to a specific post office or delivery zone. ZIP+4 adds four more for a block or building.
Why not just use a real ZIP code for testing?
Because real addresses in test data have a habit of escaping, into a test email that gets sent, a demo screenshot, a support ticket. A structurally valid but invented code exercises the same code paths without pointing anywhere real.
Does it cover territories or military addresses?
No. It covers the 50 states. Puerto Rico, Guam and the other territories have their own prefixes, and military addresses use the AA, AE and AP ranges, none of which are in the list.