How to Write An Apartment Address

Knowing how to write an apartment address might seem straightforward, but there are specific guidelines that ensure your mail reaches its destination. The key is to include all essential information in the correct order while using proper abbreviations that postal workers recognize.

Whether you’re sending a letter to a friend or expecting packages at your new apartment, using the right format can help prevent delivery delays and returned mail.

1. Center your delivery address

Start by centering your delivery address on your envelope or package. This central placement is where mail sorters and carriers automatically look first, making it easier for them to process your mail quickly and accurately.

Keep your address as concise as possible — ideally using just three lines. This clean format reduces confusion and helps postal workers read your address at a glance.

2. Write the full name of the recipient

Always use the recipient’s complete legal name on the first line. While nicknames might feel more personal, they can prevent mail delivery if the apartment mailbox or directory doesn’t list an informal name.

Using legal names becomes especially important for forwarded mail since postal services rely on official names to redirect packages and letters to new addresses.

3. Write the street name and number

The second line contains your street information and apartment details. According to USPS, everything should go on one line: street number, street name, and apartment designation.

Always include a comma after the street address when adding apartment information. This small punctuation mark helps separate the street address from the unit details.

4. Include the apartment unit number

Your apartment unit should stay on the same line as the street address. Many people mistakenly put the apartment number on a separate third line, but the preferred format is on the same line as the street address.

How to put “Apt” on an envelope

“APT” is the standard abbreviation for apartment and should appear before your unit number. You can write out “Apartment” in full, but abbreviations are actually preferred by postal services because they save space and improve processing speed.

If you’re short on space, you can use the third line for your apartment information, though this isn’t ideal. Most mail will still reach you, but including APT and the unit number on the same line as the address works best.

Common apartment address abbreviations

Using standardized abbreviations helps postal workers process mail efficiently. Here are the most common apartment-related abbreviations:

• Apartment – APT
• Basement – BSMT
• Building – BLDG 
• Department – DEPT
• Floor – FL
• Front – FRNT
• Hanger – HNGR
• Key – KEY
• Lobby – LBBY
• Lot – LOT
• Lower – LOWR
• Office – OFC
• Pier – PIER
• Penthouse – PH
• Rear – REAR
• Room – RM
• Side – SIDE
• Slip – SLIP
• Space – SPC
• Suite – STE
• Trailer – TRLR
• Unit – UNIT

5. Add the city, state, and ZIP code

Your final line should include the city, state abbreviation, and ZIP code. Use the official two-letter state abbreviation (like NY for New York or CA for California) and include the full ZIP+4 code if you know it. The ZIP+4 code is the four numbers following a ZIP code that provide the carrier with more specific information about the delivery location within your ZIP code area.

6. Include the recipient’s country if applicable

For international mail, add the country name in all capital letters on the final line. Different countries have varying address formats, so research the local conventions for your destination.

When sending abroad, write addresses in the recipient’s local language when possible. Avoid abbreviating street types, directions, or regional names unless you’re certain about local conventions. Always double-check postal codes as incorrect codes can significantly delay international delivery.

7. Write your return address 

Place your return address in the upper left corner using the same formatting rules you applied to the recipient’s address. This ensures your mail can be returned if delivery fails.

8. Add postage and ship

Before mailing, verify you have the correct postage amount based on current postal rates. You can check rates online or visit your local post office to ensure proper postage.

What happens if you don’t label the address correctly?

In most cases, improperly addressed mail won’t reach its destination and may be returned to the sender. Without proper apartment designations, mail carriers can’t determine which mailbox your package or letter should be delivered to.

Missing or incorrect ZIP codes can delay delivery, as postal services use these numbers to route mail through their processing centers. Similarly, using non-standard abbreviations or formatting can confuse sorting equipment, causing delays.

The most problematic issues occur when apartment numbers are missing entirely — your mail might end up at the building’s main office or be returned as undeliverable.

Address your future

Whether you’re settling into a new place, keeping in touch with friends, or managing important correspondence, using the proper address format ensures your mail reaches its destination smoothly.

When you’re ready to find your next address, use Zillow’s Renter Search Center to help you discover nearby apartments.