What is a ZIP+4 code and how do you find yours?
Quick answer: a ZIP+4 code is a 5-digit ZIP code plus a hyphen and four extra digits, for example 62704-1234. The extra digits identify a specific delivery segment, such as one side of a city block, a floor or group of offices in a large building, a group of PO boxes, or a single high-volume address. You do not need it for mail to arrive, but it helps the Postal Service sort mail faster.
How a ZIP+4 is structured
| Part | Example | Meaning |
|---|---|---|
| 1st digit | 6 | National area (a group of states) |
| 2nd-3rd digits | 27 | Sectional center facility (regional sorting hub) |
| 4th-5th digits | 04 | Post office or delivery area |
| Hyphen + 4 digits | -1234 | Delivery segment within that ZIP |
| (Delivery point, hidden in barcode) | 2 more digits | The exact delivery point, usually from the house number |
The Postal Service introduced ZIP codes in 1963 and added the four-digit extension in 1983.
What the last four digits identify
- One side of a street between two intersections
- A building or a floor of a large office building
- A range of PO boxes
- A single organization that receives a lot of mail
The first two of the four digits are the sector and the last two are the segment.
How to find your ZIP+4
- Use the ZIP Code lookup tool on the USPS website and enter your full street address.
- Check a recent letter from your bank or a utility; many print the full ZIP+4.
- Your tax forms or other official mail often include it.
To look up standard 5-digit ZIP codes by state, use our ZIP code directory.
Do you need to use ZIP+4?
No. Mail with a correct 5-digit ZIP code and a full street address is delivered normally. ZIP+4 is most useful for:
- Businesses sending bulk mail, which can qualify for lower postage when addresses are ZIP+4 coded and presorted.
- Online forms that ask for it for address verification.
- Making sure mail sorts quickly by machine.
How to write it
Put the ZIP+4 on the last line of the address with a hyphen and no spaces:
JANE DOE
123 MAIN ST
SPRINGFIELD IL 62704-1234See the full format in how to address an envelope.
ZIP codes vs ZCTAs
The Census Bureau publishes statistics by ZCTA (ZIP Code Tabulation Area), which are approximations of ZIP code areas, not the same thing. See ZIP codes vs ZCTAs.
Frequently asked questions
Can a ZIP+4 change? Yes. USPS can reassign the extension when delivery routes change. The 5-digit ZIP rarely changes.
Does every address have a ZIP+4? Almost every deliverable US address has one.
Is ZIP+4 the same as a postal code? It is the US version. Other countries use their own formats; see our world postal codes.