Guide
U.S. address & ZIP code format
The correct order, the most common mistakes, and what to do for PO Boxes or military mail — with a free formatter to put it together in seconds.
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Structure of a U.S. address
A domestic mailing address is written in this order:
Recipient
The person or company name receiving the mail.
Jane Smith
Street address
House/building number and street name, plus apartment, suite or unit if there is one.
456 Main St, Apt 2B
City, State ZIP
City name, a comma, the two-letter state abbreviation, one space, then the 5-digit ZIP code — all on the same line.
Austin, TX 78701
Country
Omit it for U.S. domestic mail; add it only if the letter is coming from outside the United States.
USA
Common mistakes
These are the ones most likely to delay a delivery or bounce a form:
- ✕
Putting the ZIP code on its own line — it belongs right after the state, on the city line, not below it or after the country.
- ✕
Spelling out the state name — use the two-letter abbreviation (TX, not Texas); mail-sorting equipment and most databases expect it.
- ✕
Leaving out the apartment or unit number — without it, mail can sit at the building's front desk or get returned.
- ✕
A comma between the state and ZIP code — there's a comma after the city, but none between the state abbreviation and the ZIP.
Example of a complete address
Jane Smith
456 Main St, Apt 2B
Austin, TX 78701
Special cases
Not every address follows the street-and-number pattern. Here's how each one is adjusted:
PO Box
Replace the street address line with "PO Box" and the number assigned by the post office. The city, state and ZIP line stays the same — and PO Box ZIP codes usually don't carry residential demographics, since no one lives there.
Military mail (APO/FPO/DPO)
The city line becomes the unit/ship designation, the "state" is one of AA, AE or AP, and the ZIP code routes it through the military postal system instead of a city: "Unit 2050 Box 4190, APO AP 96278".
Unique ZIP code (a single organization)
Use that organization's preferred street address and name exactly as they publish it — the ZIP code alone already routes the mail to them, regardless of the physical address on the envelope.
Address formatter
Fill in the fields and copy your address in the correct format.
Don't know your ZIP code? Find it by your locationor look it up by state and city.
Frequently asked questions
Does the ZIP code go on its own line?+
No — it goes on the same line as the city and state, right after the state abbreviation, separated by one space: "Austin, TX 78701", never on a line by itself or after the country.
Should I spell out the state name or use the abbreviation?+
Use the standard two-letter USPS abbreviation (TX, not Texas) with no periods. USPS mail-sorting equipment is built around those codes, and it's the format every address database expects.
What's the difference between a 5-digit ZIP and ZIP+4?+
The 5-digit code narrows mail down to a delivery area; the optional +4 (written 78701-1234) narrows it further, sometimes to a specific block, building or even a single high-volume recipient. It's optional for most mail but speeds up automated sorting.
How do I address a PO Box?+
Replace the street address line with "PO Box" and the number — never combine it with a street address on the same envelope. The city, state and ZIP line stays the same.
What does it mean when a ZIP code is "unique"?+
A small number of ZIP codes are assigned to a single organization — a large company, university or government agency — instead of a geographic area. Mail to that ZIP code goes straight to that organization regardless of street address.