
Writing an apartment address accurately is essential to ensure the timely delivery of mail and packages. A single mistake in the address can lead to significant delays, lost mail, and unnecessary frustration for both the sender and the recipient. Whether you are writing an apartment address on an envelope, a letter, sending mail, or filling out online forms, accuracy is essential for smooth and reliable communication. The precision in writing addresses is not just a matter of postal etiquette but a necessity for efficient communication and delivery.
According to USPS (United States Postal Service) Publication 28, writing an apartment address is a proper process. If the format is incorrect, it can create problems during delivery or make it harder for the recipient to submit a claim if the mail is lost. So, it is definitely worth your time to know the answers to how to write an address with an apartment number. Here, we have come up with the proper apartment address format, ensuring your correspondence reaches its intended destination without any hiccups.
The Essential Formula
When you are ordering something online or sending anything to your friend by post, usually there is a second line where you write the recipient’s unit or apartment number. However, here is the catch: line two doesn’t exist as per the US Postal Service. So, you have to include all the information in one line. So, what elements to include when it comes to how to write an apartment address?
- Recipient Name
- Street Number & Street Name
- Apartment/Unit Designation (including abbreviation) & Apartment/Unit Number
- City, State Abbreviation, & Zip Code

For Example:- Standard USPS Address Format:
Recipient Name (John Smith)
123 Main St Apt 4B
New York, NY 10001
How to Write Each Part of an Apartment Address Correctly
Recipient Name
The first element of the apartment address format is the recipient’s name. Write your full legal name to avoid any kind of confusion with all alphabets. This enhances readability, especially in cases of unclear handwriting. Avoid using nicknames or incomplete names, specifically when multiple residents are staying at the same address. You must also include necessary titles like (Mr., Mrs., and Ms.) to ensure transparency.
For instance – Taylor Smith
Street Number And Street Name
Street number and street name form the fundamental elements of any address. The street number comes before the street name. Write them in clear handwriting so that it is easy to read them. When you write an apartment address, always use the official street name as listed by the local postal service and avoid informal shortcuts, as even small spelling errors can cause delivery issues for mail, letters, and online orders.
For instance – 562 Barton Avenue
Apartment/Unit Designation
When writing the apartment units or designation, several abbreviations are used, such as Apt, #, Unit, Suite, or OFC. You must be consistent in using these abbreviations, especially if the recipient frequently receives the mail at that address. For instance, if you want to send mail to your boss at work, you should use “Attn”(Attention) and “C/O”(in care of) when addressing the letter so that the letter is sent to the intended recipient.
Some common abbreviations used are –
- Apartment – APT
- Building- BLDG
- Floor – FL
- Suite -STE
- Department – DEPT
- Unit – UNIT (No abbreviation)
- Basement – BSMT
- Front – FRNT
- Lobby – LBBY
- Hanger – HNGR
- Slip – SLIP
- Lot – LOT
- Pier – PIER
- Rear – REAR
- Side – SIDE
- Lower – LOWR
- Space – SPC
- Room – RM
- Trailer – TRLR
- Key – KEY
- Penthouse – PH
- Department – DEPT
- Office – OFC
Also, include a pound sign (#) when following the apartment address format. There should be a space between a pound sign and the apartment number. Don’t forget to include the directional details for the street you are sending the letter to (NE, NW, SE, and SW). Skipping it may let the package end up on the wrong side, as some cities have two different streets with the same name.
For instance – 451 Quartz St, Apt 26A
City, State Abbreviation, & Zip Code
Now comes the final line of writing the address. Include city, state abbreviation, and ZIP code. A ZIP code is usually a 5-digit number that identifies a particular postal delivery area in the United States. To further enhance the delivery speed, you can include ZIP+4 codes, which reduce the delivery time by as much as two days.
For instance – New York, NY 10024
“C/O.” and “Attn.”
Sometimes, your mail or letter is meant for one specific person within a larger household or organization, such as an office, apartment complex, or shared residence. In these cases, providing clear direction helps ensure that the mail reaches the correct individual without delay.
You should use “C/O” (Care Of) when the recipient does not directly receive mail at that address and relies on another person to accept it. This is common when writing an apartment address for temporary residents, shared housing, or family members who are not the primary occupants.
Example format using C/O:
Recipient’s Legal Name
C/O Primary Resident’s Name
Street Address, Apartment Number
City, State Abbreviation, ZIP Code
You should use “Attn.” (Attention) when sending mail to a specific person within a business, department, or organization, especially in professional or office settings. This helps internal mail handling and ensures your letter is routed correctly.
Example format using Attn.:
Attn: Recipient’s Legal Name
Company or Organization Name
Street Address, Apartment or Suite Number
City, State Abbreviation, ZIP Code
Using Attn. And C/O correctly is especially important when you write an apartment address on a letter or envelope, as it reduces confusion and improves delivery accuracy.
International Mail
When sending international mail, writing an apartment address correctly is even more important because postal systems vary by country. Always write the recipient’s name first, followed by the street name and apartment number, then the city and postal code, and finally the country name written in capital letters on the last line. Avoid abbreviations unless they are commonly used in the destination country. For international letters and packages, writing the apartment address clearly helps prevent delivery delays and customs issues.
Abbreviations and Their Proper Application
When writing an apartment address, using the right abbreviations helps avoid confusion and delivery issues. These short forms make it easier for postal workers and couriers to find the correct unit quickly. Below are some common apartment address abbreviations and how to use them.
APT (Apartment):- APT is the most common abbreviation used for apartment numbers.
Example:
123 Maple St, APT 45
BLDG (Building):- Use BLDG if the property has multiple buildings. This helps identify the exact structure.
Example:
123 Maple St, BLDG B, APT 45
STE (Suite):- STE is mostly used for offices, but can also appear in residential buildings.
Example:
123 Maple St, STE 200
FL (Floor):- In tall buildings, adding the floor number can make delivery easier.
Example:
123 Maple St, FL 15, APT 45
UNIT:– UNIT is another simple way to show the apartment number. It is commonly used in condos and townhomes.
Example:
123 Maple St, UNIT 45
# (Number Symbol):- The # symbol is a quick way to write apartment numbers, especially in casual formats.
Example:
123 Maple St, #45
Some Examples of Clarity
Let’s help you understand this with the help of a few examples –
1) Single Recipient:
If you are sending the letter to a single recipient –
Taylor Smith
451 Quartz St, Apt 26A
Brooklyn, NYC 71834-2341
2) Multiple Recipients:
If you are sending the letter to multiple recipients –
Taylor Smith
Jane Smith
451 Quartz St, Apt 26A
Brooklyn, NYC 10023
3) Apartment Complex with Building Number:
If you are sending the letter to larger apartment complexes with multiple buildings, include the building number –
Taylor Smith
Building 2, Apt 26a
Willow Creek Apartments
342 Magnolia St
Brooklyn, NYC 10023
Including the building name or number helps the mail carrier locate the correct unit within the complex.
How to Change Your Address After Moving
If you’ve recently relocated or are planning a move across state lines, interstate moving services can ensure your belongings are handled with utmost care and will deliver them to your updated address. You have to change your address and notify many departments if you have decided to move to a new residence. Use your legal name whenever you are signing up for new services. Notify the post office, update your address on online accounts, and inform your friends and family to receive everything at the right place and avoid any headaches.
Common Mistakes to Avoid When Formatting Addresses
Even a small formatting issue can affect mail delivery or confuse deliveries and moves. Paying attention to details helps ensure your apartment address is easy to locate.
Common mistakes to watch out for:
- Leaving out the apartment or unit number
- Placing the apartment number on a separate line unnecessarily
- Using inconsistent or incorrect abbreviations
- Forgetting directional details like NE, NW, SE, or SW
- Misspelling the street name or city
- Using nicknames instead of the recipient’s legal name
When you write an apartment address correctly, postal services and delivery teams can identify your exact unit without delays. This is especially helpful during moves, when accurate address details save time, something our Local Moving Services and Packing Services help manage smoothly.
Conclusion
Putting the apartment number in the address is a small but significant detail that ensures your mail and packages are delivered promptly and correctly. With the above-mentioned tips in mind, you’ll be well-equipped to write precise and effective apartment addresses, enhancing your overall mailing experience.
Additionally, if you have recently moved, updating your address promptly with all necessary parties will ensure a smooth transition and prevent any disruptions in your mail delivery. You can get assistance from professional moving companies to move your belongings to the right address and guide you toward a comfortable moving experience. Big Apple Moving is one such reputed name in the moving industry.
All in all, accurate addresses not only improve your personal and professional communications but also make the work of movers and delivery services more efficient and reliable.
Frequently Asked Questions
How do you write an address with an apartment number?
Write the apartment number on the same line as the street address, after the street name, using Apt or Unit followed by the number.
Is address line 2 for the apartment number?
No. According to USPS, the apartment number should be included on the same line as the street address, not on a separate second line.
What goes in Address Line 2?
Address Line 2 is typically used for additional location details such as an apartment, suite, unit, or floor number. For physical mail, USPS prefers apartment or suite numbers to be included on Address Line 1 along with the street address. For online forms, many websites require apartment or suite numbers to be entered in Address Line 2 instead.
What is the correct address format?
The correct format is recipient name, street address with apartment number, then city, state abbreviation, and ZIP code.
Where does the return address go on an envelope?
The return address is written in the top left corner of the envelope, using the same format as the delivery address.
How to write an apartment address on a letter?
Write the recipient’s name first, then the street address with the apartment number on the next line, followed by the city, state, and ZIP code below it.












