How to Address an Envelope (USPS Format)

The short answer

Write the recipient’s address in the lower middle of the envelope front, parallel to the long edge: the name on the first line, an optional company line, the street address with any apartment or suite number, then the city, state, and ZIP Code together on the last line. Put your return address in the upper left corner and the stamp in the upper right. USPS prefers capital letters with no commas or periods, and it needs the bottom 5/8 inch left clear for its barcode.

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Where each part goes on the envelope

Hold the envelope with the long edge running left to right. The recipient’s address, your return address, and the postage all go on this same side: USPS requires the delivery address to appear only on the side that bears postage, and asks that both addresses be written parallel to the longest side.

Machines read the recipient’s address before any person does, so its position matters as much as its neatness. USPS recommends keeping it inside the optical character reader (OCR) read area, which runs from 5/8 inch to 2 3/4 inches above the bottom edge, with 1/2 inch margins on the left and right. On an ordinary letter envelope, that puts the address in the lower middle of the front.

Envelope layout at a glance
Part	Where it goes	Why it matters
Return address	Upper left corner of the front	Tells USPS where to send the letter if it can’t be delivered.
Postage stamp	Upper right corner of the front	USPS requires stamps to be affixed in the upper right corner of the address side.
Recipient address	Lower middle of the front, parallel to the long edge	This is the area USPS scanners read. An address parallel to the short side makes a letter nonmachinable.
Extra service labels	Above the recipient address, right of the return address or left of the stamp	Keeps labels such as Certified Mail clear of the address block.
Bottom 5/8 inch	Leave it blank, especially the right-hand 4 3/4 inches	USPS prints its Intelligent Mail barcode in this clear zone.

What to write on each line of the recipient address

USPS lists the parts of a delivery address in a fixed order from the top line down. Most personal letters need three lines; a letter to a specific person at a business usually needs four.

Apartment and suite designators such as APT, STE, UNIT, BLDG, FL, and RM belong at the end of the street line. If that line runs out of room, USPS allows the unit to go on the line immediately above the street address, never below it. Use the pound sign only when you don’t know the right designator, and leave a space after it, as in # 14B.

Include directionals such as NW or E: USPS’s own addressing guide points out that a town may have more than one Main Street. Leave phone numbers off the delivery address.

Name line: the recipient’s full name, or the organization’s name if you are writing to it generally.
Company line (optional): when you write to a person at a business, put the person’s name, or ATTN and the name, above the company name, which is the order USPS Publication 28 shows.
Street line: the house or building number, the street name with any directional and suffix, and the apartment or suite number at the end, such as 1200 N LAKE SHORE DR APT 14B.
Last line: city, two-letter state abbreviation, and ZIP Code on one line, with the four-digit ZIP+4 extension if you know it.

Envelope address examples

These examples use placeholder names and ZIP Codes; replace every part with the recipient’s real details. Each row reads top to bottom on the envelope, from the name lines to the last line.

Example recipient addresses
Situation	Name lines	Street line	Last line
House	JANE RIVERA	482 OAK HILL RD	ANYTOWN NY 12345-6789
Apartment	MARCUS LEE	1200 N LAKE SHORE DR APT 14B	ANYTOWN IL 12345
Person at a business	ATTN MARIA LOPEZ, then BRIGHT HARBOR DENTAL on the next line	75 MAIN ST STE 210	ANYTOWN OH 12345-6789
PO Box	SAM OKAFOR	PO BOX 1234	ANYTOWN TX 12345-1234
Guest at someone else’s home	ELENA PARK, then C/O DAVID KIM on the next line	19 BIRCH LN	ANYTOWN WA 12345
Military (USPS’s example)	SGT JOHN SMITH	UNIT 2340 BOX 132	APO AE 09350

Capitals, punctuation, and spacing

USPS accepts handwritten addresses, but the closer you get to its machine-readable style, the less likely your letter is to need manual handling. These preferences come from USPS Publication 28 and the Domestic Mail Manual.

Use capital letters. Publication 28 prefers uppercase on every line of the address; neat lowercase is acceptable as long as it stays readable.
Skip commas and periods. Punctuation may be omitted everywhere except the hyphen in a ZIP+4 Code, and USPS’s consumer guide says not to use commas or periods.
Line up the left edge. Start every line at the same left margin and keep the lines parallel to the bottom of the envelope.
Keep city, state, and ZIP Code together on the last line with at least one space between them. When typing, USPS prefers two spaces between the state and the ZIP Code.
Use standard abbreviations: two-letter state codes and USPS street and unit abbreviations such as ST, AVE, BLVD, APT, and STE.
Write clearly in dark ink on a light background. USPS suggests a pen or permanent marker that is legible from an arm’s length away. Printed addresses should be at least 8-point type, and a sans-serif font is preferred.
Use a street address or a PO Box, not both. If both appear, USPS delivers to the line immediately above the city, state, and ZIP Code.

How to write the return address

Write your own address in the upper left corner of the front, in the same format as the recipient’s: your name on the first line, your street address or PO Box with any unit number on the second, and your city, state, and ZIP Code on the third.

The return address is how USPS sends back mail it can’t deliver. USPS says a return address is required on most mail, and the Domestic Mail Manual requires one for services such as Priority Mail, Registered Mail, insured mail, and Certified Mail with a return receipt. If you leave your name off, the return address still needs another clear identifier, such as an apartment or suite number.

Use a US return address on domestic mail. USPS can’t return an undeliverable domestic letter that carries a foreign return address; it handles that piece as dead mail.

Postage, and addressing mistakes that cost extra

The stamp goes in the upper right corner. At USPS retail prices effective July 12, 2026, postage for a 1-ounce stamped letter is $0.82, and each additional ounce up to 3.5 ounces adds $0.29, so a 2-ounce letter is $1.11. USPS changes prices periodically, so check the current price list before you buy.

How you address and pack a letter can also raise the price. USPS adds a $0.49 nonmachinable surcharge to letters with certain characteristics, including an address written parallel to the short side, an envelope whose length divided by its height is less than 1.3 or more than 2.5 (square envelopes fall in this group), clasps or strings, contents too rigid to bend, and lumpy items such as keys or coins.

Military, PO Box, care-of, and international addresses

For APO, FPO, or DPO mail, replace the city with APO, FPO, or DPO and the state with AA (Armed Forces Americas), AE (Europe, the Middle East, Africa, and Canada), or AP (Pacific), followed by the ZIP Code. The line above shows UNIT, CMR, or PSC with its number and the box number. Use the service member’s full name, and don’t add the host country or the base’s city: USPS warns that the letter might then be routed through that country’s mail system.

A PO Box takes the place of the street line, written as PO BOX and the number. When the recipient is staying at someone else’s address, add a C/O line under their name. The linked guides cover line order, Street Addressing, and when ATTN fits better than C/O.

For mail leaving the United States, put the country name by itself on the last line. IRIS can’t help with that one, because it mails only to US addresses.

Mailing online: let IRIS print the address

If you’d rather not address an envelope at all, IRIS can print and mail a finished PDF letter. Instead of writing on an envelope, you enter the return and recipient addresses in labeled fields: Name or company (up to 40 characters), Street address, an optional Apt, suite, unit line, City, a two-letter State, and a five-digit ZIP Code or ZIP+4. IRIS prints and addresses the letter and submits it to USPS with First-Class postage included.

A letter costs $3 plus $0.20 per black-and-white page or $0.40 per color page, so a one-page black-and-white letter is $3.20; Certified Mail adds $6.95. Address suggestions appear as you type, but they are advisory, so compare the result with the address the recipient gave you before you pay. IRIS mails individual letters and postcards to US addresses only, and it doesn’t sell stamps or envelopes.

Sources & further reading

Product details checked against the IRIS API contract when this article was published. Platform references can change; consult the linked documentation when implementing.

Published by IRIS Postal Forms, operated by Great Lakes Computing Office LLC. Send a correction.

Put it into practice

Skip the envelope and the stamp

Upload a finished PDF letter, enter both addresses in labeled fields, and check the full price before checkout. IRIS prints, addresses, and mails it to a US address.

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