ZIP Codes in Newmarket, NH
Newmarket uses 1 ZIP code, all in Rockingham County. Pick one below for details, or look up the full nine-digit ZIP+4 for a specific street address.
All 1 Newmarket ZIP codes
| ZIP | Type | County | Population |
|---|---|---|---|
| 03857 | standard | Rockingham | 9,463 |
Finding a ZIP+4 in Newmarket
Knowing which of these 1 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 Newmarket 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 Newmarket addresses and download it complete.