ZIP Codes in Janesville, WI
Janesville uses 3 ZIP codes, all in Rock County. Pick one below for details, or look up the full nine-digit ZIP+4 for a specific street address.
All 3 Janesville ZIP codes
| ZIP | Type | County | Population |
|---|---|---|---|
| 53545 | standard | Rock | 24,703 |
| 53546 | standard | Rock | 29,867 |
| 53548 | standard | Rock | 19,916 |
Finding a ZIP+4 in Janesville
Knowing which of these 3 ZIP codes covers an address only gets you partway. The four-digit extension identifies the specific delivery point — typically one side of one block. Two houses facing each other on the same Janesville street almost always have different ZIP+4 codes even though they share all five leading digits.
Appending ZIP+4 to a mailing list?
Upload a CSV of Janesville addresses and download it complete.