If you ever find yourself staring blankly at an envelope and thinking, “Where do I put the apartment number?”—trust me, I’ve been there too.
I still remember the first time I had to send something to my long-distance friend who was living in an apartment. I second-guessed everything I wrote. “Do I put the unit on the same line as the street?” “Should I write ‘Apt’ or just the number?” I had no idea how to write apartment address details correctly, and it made the process feel way more complicated than it actually was.
It was literally such a frustrating moment, even though it’s a simple process. But once you understand how to address an envelope correctly—especially when it includes an apartment number—it all clicks. And if you’re also interested in the creative side of mailing, learning how to make an envelope from scratch is just as satisfying. Check out this DIY folding video tutorial to get started!
I listed the standard apartment address structure below, even though I follow this every single time, and it hasn’t failed me yet:
- Full Name of the recipient
- Street Address followed by Apartment Number
- City, State, ZIP Code
Example:
John Smith
465 Main Street, Apt 8C
New York, NY 10001
How to Write Apartment Address on an Envelope: Using ‘Apt’ Correctly in Your Address
When I first started mailing to my family living in an apartment, the word “Apt” used to confuse me on a vast level. “Do I write it with a comma?” “Or should I just write the number?” Honestly, it felt like such a small detail, but no one wants their mail to get lost just because we wrote one damn thing wrong.
After a few error moments and failed trials (one letter even returned to me), I finally figured out what works best and what the USPS recommends.
The simple rule: Always include “Apt” before the number so it’s clear to the mail carrier that it’s an apartment unit, not part of the street address.
If you’re wondering how to write apartment address an Envelope correctly, whether you write it with a comma or without, both are acceptable. Just write it on the same line as the street address.
Let me know if you’d like any more adjustments!
Examples:
465 Main Street, Apt 8C
987 Main St, Apt 6A
Tip from experience:
Keep it neat, short, and consistent. The clearer your address is, the less chance of your mail ending up in the wrong hands.
Should I Put the Apartment Number Below the Street Number?
Okay, so let’s be honest, we all get confused about this question when we first start sending mail to an apartment: ‘How to write an apartment address on an envelope? Should I write the apartment number on a new line? Or just place it right after the street name?’ I even asked my neighbor once because I didn’t want my letter to end up in the wrong mailbox.
After some failed/successful trials, I finally learned what works. Here’s what I know: Best Practice: Keep the apartment number on the same line as the street address, right after it.
You can separate it with a comma or a space; both are fine. Just avoid writing the apartment number below the street line unless it’s necessary (like if you’re out of space).
Example:
| Correct: | Avoid: |
| 123 Main Street, Apt 4B New York, NY 10001 | 123 Main Street Apt 4B New York, NY 10001 |
So now, whenever you write an apartment address, keep it all in one line, and it’ll be smooth.
How to Write Abbreviations in Any Address
I still remember my friend’s reaction when she first saw “STE” on an envelope and said, “Wait… what does STE mean in address?” Back then, we didn’t know there were so many abbreviations people used in mailing addresses. It may seem a bit overwhelming at first, but trust me, it all starts making sense once you get used to them—especially when you’re learning how to write apartment address formats correctly.
These abbreviations help to keep the address short and neat, and yes, they are totally accepted by USPS.
So the following are the most common abbreviations that’ll help you—now I use them and understand them clearly:
| Type | Abbreviation | Example |
| Apartment | APT | 868 Main St, APT 6 |
| Building | BLDG | 457 Main St, BLDG D |
| Floor | FL | 231 Main St, BLDG E, FL 3 |
| Suite | STE | 908 Main St, STE 4 |
| Room | RM | 615 Main St, RM 5 |
| Department | DEPT | 997 Main St, DPT 283 |
| Unit | Unit | 464 Main St, Unit 1 |
Less Common Abbreviations
(Use only when they match the location you’re mailing to)
| Type | Abbreviation |
| Basement | BSMT |
| Front | FRNT |
| Lobby | LBBY |
| Hanger | HNGR |
| Slip | SLIP |
| Lot | LOT |
| Pier | PIER |
| Rear | REAR |
| Side | SIDE |
| Lower | LOWR |
| Space | SPC |
| Trailer | TRLR |
| Key | KEY |
| Office | OFC |
International Apartment Addresses
We all pass through that phase when we first had to mail something overseas. In my case, I was sending to my friend in Canada, and honestly, I got paused. Their address looked different, and I wasn’t sure how to write apartment address details correctly—should I write the apartment number first or after the street? And that postal code was just so confusing; it was so different from what I was used to!
I listed down some of my experiences and what I learned through experts: International apartment addresses often follow different formats. In some countries, the unit and apartment number come before the street name. In others, it comes after, so it’s super essential for us to double-check the format based on that country.
And also, write the address in English or the country’s preferred mailing language; it’ll avoid confusion during processing.
Sample Format (International)
Alex Johnson
Unit 5B, 123 Queen Street
Toronto, ON M5V 2B6
CANADA
Once you get used to it, international mailing won’t look scary, just a few extra details to keep in mind.
Step-By-Step Instructions for Writing an Apartment Address
If you are anything like me, writing an apartment address used to feel like a guessing game for me. I used to keep checking examples online, wondering if I was doing it right. But after a few experiences and learning, If you are confused in ‘how to write an address with an apartment number’ or some other things aswell, this step-by-step method will guide you clearly.
Place Your Delivery Address in the Center of Your Mail
So this is the first thing you need to get right. Your recipient’s address should go right in the center of the envelope, both horizontally and vertically.
Mini Tip:
Leave some space around the edges so nothing gets cut off or hard to read.
Begin with the Full Name of the Recipient
No nicknames here! Start with the full name of the person you’re sending mail to.
Example: John Smith
Write the Street Name and Number on the Second Line
Write the street number on the next line, followed by the street name
Example: 465 Main Street
Write the Apartment Unit Number on the Second Line
This part confuses all of us at first, but here’s the solution: Add the apartment or unit number after the street address on the same line.
Example: 465 Main Street, Apt 8C
Both with or without a comma are fine, just keep it clear.
Write the City, State/Province, and ZIP Code on the Third Line
Next, on a new line, add the city, state or province, and ZIP/postal code.
Example: New York, NY 10001
Add the Recipient’s Country If Shipping Internationally
If you are sending outside of your country, this part is most important. Write the country in ALL CAPS on the last line.
Example: CANADA
It helps with international sorting and delivery.
Remember to Write Your Return Address
I’ve had a letter come back to me once just because I forgot the return address. So make sure to add your name and address in the top left corner of the envelope.
This way, if there’s an issue, your mail can return safely.
Add Postage Based on Rates
Lastly, don’t forget the stamp. Place it in the top right corner of the envelope.
Use a Forever Stamp for U.S. mail or check rates for international shipping.
Once you practice and get used to this simple format, writing apartment addresses becomes easier and more fun. And your mail gets to the right place without any stress.
Mini Tip:
Too little postage = undelivered mail. Too much = just a waste.
Common Mistakes When Writing an Apartment Address
You might think tiny mistakes won’t matter, but it’s not true! Even minor address errors can stop your mailing from arriving. Even I had letters returned, delayed, or totally lost just because of things I never thought twice about before—like how to write apartment address details correctly. I listed some common mistakes to avoid.
- Using Commas and/or Periods in the Wrong Place:
If you add too many commas, then the mail sorter will probably get confused. Keep punctuation simple, only use a comma if needed (like between street name or apartment number) and skip the periods.
- Including City and Street Abbreviations:
Informal short forms can cause issue with the delivery, so learn to go with official abbreviations like “NY” for state or “St” for street.
Forgetting Neat Handwriting:
If your writing is messy, your letters might be misdelivered. Now, use block letters or print neatly. If someone can’t read it correctly, your mail might not make it.
- Inserting the Wrong ZIP Code:
You might think it’s just a few numbers, but if even one of the numbers is wrong, your letter could go to the wrong city. Always double check the ZIP code before sealing the envelope.
- Not Including Common Abbreviations like “Apt” or “Bldg”:
Always use proper abbreviations so the address makes complete sense. I used just to write the number, like “5B” but the mail carrier had no idea what that meant without “Apt” or “Unit.”
By avoiding these little mistakes as well, your mail will be successfully delivered in the right place. Once you know what to look out for, your apartment mail will be more reliable and less stressful!
What Happens if You Write an Address Incorrectly?
Every detail matters. When you write an address incorrectly—whether it’s the ZIP code, missing apartment info, or messy handwriting—it can cause a lot of problems. Your letter might get delayed, lost, or even returned to you. That’s why understanding how to write apartment address information properly is so important. USPS and other postal services have rules to sort mail quickly; a little inaccuracy and your letter gets lost.
A clear and correct address means your message gets where it’s supposed to go. You don’t have to worry about it later then!
