When changing apartments, you have to update your address in a number of different places, such as the bank and the post office. You have to make sure that you write the address correctly so that there is no ambiguity or confusion when anything has to be delivered to your apartment.

In this post, we’re going to guide you on how you can do that.

The Standard Format for Apartment Addresses

Let's start with the basics. A correctly written apartment address follows this structure:

Line 1: Recipient's full legal name

Line 2: Street number + street name + unit designator + unit number

Line 3: City, state abbreviation, ZIP code

A real example looks like this:

                                    James R. Sullivan

                                  123 Bedford Ave, APT 4B

                                   Brooklyn, NY 11211

Should the Apartment Number Go on the Same Line or a Separate One?

On envelopes, the apartment number goes on the same line as the street address, right after the street name. USPS prefers it this way because it keeps the delivery address on one clean line, which reduces sorting errors.

This is the correct way:

                                     123 Bedford Ave, APT 4B

It should not be done like this:

                                      123 Bedford Ave

                                      APT 4B

On online forms, you'll usually see an "Address Line 1" and "Address Line 2" field. Use them as intended: street address on Line 1, apartment number on Line 2.

If a form only gives you one address line, just put everything together: 123 Bedford Ave APT 4B. Don't leave the unit number out just because there's no dedicated field for it.

APT vs. UNIT vs. #: Which One Should You Use?

All three are understood and accepted by USPS. But there are situations where one works better than the others.

USPS officially recommends APT or UNIT over the # symbol. Mail sent with # still gets delivered without issue in most cases, but on official documents like lease applications, bank forms, and government paperwork, stick with APT or UNIT.

Some systems don't parse the # symbol cleanly, which can cause a mismatch you won't notice until something gets rejected.

When in doubt, go with APT. It's the most universally recognized and least likely to cause issues anywhere.

Common Apartment Address Abbreviations

You'll find guides online that provide 25+ address abbreviations. Realistically, these are the ones you'll actually encounter:

If your building uses something that isn't on this list, write it out in full. A mail carrier who has to guess what an abbreviation means is a mail carrier who might deliver your package to the wrong place.

The official full list of USPS-approved abbreviations is available on usps.com if you ever need to look something up.

Sending Mail to Someone at Your Apartment Using "C/O"

C/O stands for "care of." You use it when someone needs to receive mail at your address but isn't the primary resident. This comes up a lot during moves, when someone is temporarily staying with a friend or family member while getting settled.

It looks like this:

                                                     Daniel Park

                                            C/O James Sullivan

                                       123 Bedford Ave, APT 4B

                                            Brooklyn, NY 11211

This tells the postal carrier that Daniel is receiving mail at James's address. Simple, and it prevents a lot of confusion at the mailbox.

Sending Mail to a Specific Person Using "ATTN"

ATTN stands for "attention." You use it when your mail is going to a business or organization and needs to reach a specific person there. It's less common in a purely residential context, but if you work from home and receive business correspondence, it's worth knowing.

It looks like this:

                                            ATTN: James Sullivan

                                           Sullivan Creative LLC

                                      123 Bedford Ave, APT 4B

                                           Brooklyn, NY 11211

The distinction is straightforward: C/O is for personal mail going to someone at another person's residence, and ATTN is for professional mail going to a specific person at a business address.

Writing an Apartment Address if You're Moving to NYC From Abroad

If you're relocating to New York from another country, the address format you're used to back home probably looks pretty different from the American standard. Here's a quick comparison so you know what to expect when you're filling out forms, signing a lease, or getting mail forwarded to your new place.

The biggest adjustment for most people is that American addresses go from smallest to largest: street number first, then street name, then city, then state, then ZIP. If you're coming from Japan or parts of Asia where it's the opposite, it takes a little getting used to.

For your NYC apartment specifically, the format is just the standard one we covered above. Something like

                                                       Yuki Tanaka

                                           123 Bedford Ave, APT 4B

                                             Brooklyn, NY 11211

One thing worth noting: when you're receiving mail from someone back home, make sure they write USA at the bottom of the address. International postal services need that to route it correctly.

Common Mistakes to Avoid When Writing an Apartment Address

Most address errors aren't obvious until something goes wrong. A returned package or a rejected form submission is usually the first sign. Here are the ones that come up most often:

1. Leaving out the apartment number. This is the big one. A street address without a unit number sends your mail to the building, not your door. Carriers will often return it rather than guess which unit it belongs to.
2. Using a nickname instead of your legal name. The building has you on record under your legal name. Mail addressed to "Jamie" when you signed the lease as "James" can get held or returned without explanation.
3. Using the wrong ZIP code. Large buildings and complexes sometimes span more than one ZIP code or have a different ZIP for P.O. box versus physical delivery. If something keeps bouncing back, this is worth checking first.
4. Not updating your address before your first delivery arrives. If you order something the day you move and forget to switch your address, it goes to your old place. Update your accounts before the boxes start coming.

Wrapping Up

And that’s where our comprehensive guide on how to write an address properly comes to an end.

The format is simple and straightforward. Writing an address properly is more about remembering what not to do and what mistakes not to make. We’ve covered those extensively in the article above as well.