If you are wondering whether to write PO Box or P.O. Box, both forms are correct. The difference is mainly a matter of punctuation and style.
PO Box is the simple, modern form, while P.O. Box is the traditional form with periods. Both abbreviations stand for Post Office Box, a numbered mailbox provided by a postal service for receiving mail.
For example, both of these forms can be understood:
PO Box 123
P.O. Box 123
If you are writing a modern mailing address and there is no specific formatting requirement, PO Box is usually the cleaner choice. However, when reproducing an official address, it is best to follow the format supplied by the postal service or organization.
PO Box or P.O. Box: Which Is Correct?
PO Box and P.O. Box are both correct forms of the abbreviation Post Office Box.
The main difference is punctuation:
- PO Box — unpunctuated form
- P.O. Box — punctuated form
The unpunctuated version is common in modern writing and addresses, while the punctuated version reflects a more traditional style of abbreviation.
PO Box
PO Box uses no periods after the letters.
Please send the application to PO Box 500.
This form is concise and easy to read, which makes it particularly useful in mailing addresses, forms, websites, and business documents.
P.O. Box
P.O. Box uses periods after both initials.
Please send the application to P.O. Box 500.
This is also a correct form and may still appear in older documents, established organizational styles, and traditional writing.
Quick Comparison
| Form | Correct? | Description |
| PO Box | ✅ Yes | Modern, unpunctuated form |
| P.O. Box | ✅ Yes | Traditional, punctuated form |
| PO. Box | ❌ No | Inconsistent punctuation |
| P.O Box | ❌ No | Missing the second period |
| POBox | ❌ No | Words incorrectly combined |
| P O Box | ❌ No | Nonstandard spacing |
Should You Write PO Box or P.O. Box?
If you simply need to choose one form, PO Box is generally the best modern choice.
It is shorter, clean, and easy to read. Many contemporary writing styles avoid periods in common abbreviations, which makes PO Box a natural choice.
However, there is no need to treat P.O. Box as an incorrect spelling. It is an established form and is still widely recognizable.
Which Form Is Better for Modern Writing?
For general modern writing, PO Box is a straightforward choice.
For example:
Our mailing address is PO Box 250.
The same sentence can also be written as:
Our mailing address is P.O. Box 250.
If you are creating a website, business form, letter, or other document without a required style, consistency matters more than choosing between the two forms.
Which Form Should You Use in an Address?
For a mailing address, PO Box is a clear modern format:
Maria Johnson
PO Box 250
Denver, CO 80202
If an official organization provides its address as P.O. Box 250, you can reproduce that format exactly.
The most important thing is to use the correct PO Box number, city, postal code, and other required address information.
What Does PO Box Stand For?
PO Box stands for Post Office Box.
A Post Office Box is a numbered mailbox associated with a post office. Instead of having mail delivered to a person’s home or business street address, mail can be addressed to the assigned PO Box.
For example:
John Smith
PO Box 456
Boston, MA 02108
In this example, 456 is the PO Box number.
Why Do People Use a PO Box?
Individuals, businesses, and organizations may use a PO Box for several reasons.
A PO Box can provide:
- A dedicated mailing address
- A secure location for receiving mail
- An alternative to using a home address for correspondence
- A consistent mailing address when a person moves
- A separate mailing address for a business or organization
The services available through a PO Box can vary depending on the postal provider and country.
PO or P.O.: Which Abbreviation Is Correct?
Both PO and P.O. are established ways of abbreviating Post Office.
The difference is punctuation rather than meaning.
PO = Post Office
P.O. = Post Office
Therefore:
PO Box = Post Office Box
and:
P.O. Box = Post Office Box
Modern writing often omits periods from familiar abbreviations, while traditional styles may retain them.
Why Does PO Sometimes Have Periods?
Periods have traditionally been used to show that letters are abbreviations.
For example:
P.O. = Post Office
In many modern styles, periods are omitted from familiar initialisms and abbreviations:
PO = Post Office
This is why both forms can be encountered in real-world writing.
How to Write a PO Box Address
When writing a mailing address, the PO Box line normally identifies the recipient’s mailbox.
A basic example is:
John Smith
PO Box 123
Chicago, IL 60601
The exact addressing requirements can vary depending on the postal service and destination, so follow the applicable postal guidelines when sending important mail.
PO Box Address Example
Here is a simple U.S.-style example:
Sarah Williams
PO Box 789
Phoenix, AZ 85001
The first line identifies the recipient.
The second line gives the PO Box number.
The final line provides the city, state, and ZIP Code.
Where Does the PO Box Go in an Address?
In a basic mailing address, the PO Box information is normally placed on its own line between the recipient’s name and the city, state, and postal code.
For example:
ABC Company
PO Box 1000
Dallas, TX 75201
The exact format can vary depending on the destination and postal service, so use the recipient’s stated address whenever one is provided.
Do You Need a Street Address With a PO Box?
Not necessarily.
A PO Box can serve as the mailing address for mail intended for that box. However, whether a street address is required or whether a particular delivery can be made to a PO Box depends on the sender, carrier, service, and destination.
If you are filling out a form, check whether it specifically asks for a street address, mailing address, or PO Box.
PO Box vs. Street Address
A PO Box and a street address are not the same thing.
A PO Box identifies a mailbox associated with a post office, while a street address identifies a physical location.
| PO Box | Street Address |
| Identifies a numbered postal box | Identifies a physical location |
| Example: PO Box 123 | Example: 123 Main Street |
| Used for receiving mail at a post office | Used to identify a building or property |
| Does not normally identify a person’s physical location | Identifies a physical location |
For example:
PO Box 123
Chicago, IL 60601
is different from:
123 Main Street
Chicago, IL 60601
Can a PO Box Be Used as a Mailing Address?
Yes. A PO Box is specifically intended to provide a mailing address for receiving mail through the postal service that operates the box.
However, not every delivery service or sender necessarily handles PO Boxes in the same way. If you are expecting a package or completing an online form, check the relevant delivery requirements.
PO Box and Physical Address Are Not Always Interchangeable
A form may ask specifically for a physical address rather than a mailing address.
If it asks for a physical or street address, entering a PO Box may not satisfy the requirement.
If it asks for a mailing address, a PO Box may be appropriate.
Always follow the instructions provided by the organization or service.
Is PO Box Capitalized?
In a mailing address, PO Box is normally written with capital letters.
For example:
PO Box 500
The same applies to the traditional form:
P.O. Box 500
In ordinary prose, you may see variations depending on the writing style, but PO Box is a clear and conventional form.
Should “Box” Be Capitalized?
In a mailing address, Box is conventionally capitalized as part of the address designation:
PO Box 123
In ordinary prose, capitalization may vary depending on the style and sentence.
For example:
The company receives mail at its PO Box.
Common PO Box Formatting Mistakes
Several incorrect variations appear because writers are unsure where to place periods or spaces.
PO. Box
PO. Box mixes the unpunctuated and punctuated forms.
❌ PO. Box 123
Use either:
✅ PO Box 123
or:
✅ P.O. Box 123
P.O Box
If you use the traditional punctuated form, both initials should have periods.
❌ P.O Box 123
✅ P.O. Box 123
POBox
PO Box consists of two words.
❌ POBox 123
✅ PO Box 123
P O Box
The letters should not normally be separated by spaces.
❌ P O Box 123
✅ PO Box 123
po box
Lowercase po box may appear in casual digital searches or text, but a properly formatted mailing address normally uses:
PO Box 123
PO Box Examples
Here are examples showing how the term can be used in different situations.
In a Mailing Address
David Brown
PO Box 321
Austin, TX 78701
In a Sentence
Please send the completed form to our PO Box.
In Business Writing
The company receives all correspondence at its PO Box.
In Formal Writing
The organization maintains a Post Office Box for official correspondence.
Using the Traditional Form
Send all documents to P.O. Box 875.
All of these examples communicate the same basic concept, although the punctuation style differs.
PO Box in Formal and Professional Writing
Both PO Box and P.O. Box can be used in professional writing.
If your workplace, organization, publication, or client follows a specific style guide, follow that guide.
If there is no established preference, PO Box is a clean and modern choice.
For example:
Please mail the signed contract to PO Box 250.
There is no need to use P.O. Box simply because the document is formal. Formal writing does not require periods in every abbreviation.
Consistency Matters
The most important rule is to be consistent.
If you choose PO Box, use that style throughout the document:
PO Box 100
PO Box 200
PO Box 300
If a document follows a style that uses P.O. Box, maintain that form consistently:
P.O. Box 100
P.O. Box 200
P.O. Box 300
Avoid switching between styles without a reason.
PO Box and International Addressing
The term PO Box is widely understood in English, but postal addressing conventions can differ between countries.
For international mail, the safest approach is to follow the address exactly as provided by the recipient and use the formatting recommended by the relevant postal service.
For example, don’t assume that a U.S.-style city, state, and ZIP Code format applies to every country.
The punctuation in PO Box is generally a style question, while the correct placement of postal information can be a matter of local addressing requirements.
PO Box or P.O. Box: Quick Answer
If you need the answer quickly:
PO Box and P.O. Box are both correct.
PO Box is the simpler modern form without periods.
P.O. Box is the traditional form with periods.
Both mean Post Office Box.
If there is no specific style requirement, PO Box is usually a clear and practical choice. If you are copying an official mailing address, use the format supplied by the organization or postal service.
Frequently Asked Questions
Is PO Box or P.O. Box better?
Both are correct. PO Box is generally the cleaner modern form, while P.O. Box is the traditional punctuated form. If you have no specific style requirement, PO Box is a simple choice.
Should PO Box have periods?
No periods are required in the modern form PO Box. The traditional form P.O. Box uses periods. Both forms are correct.
Is PO Box correct?
Yes. PO Box is a correct abbreviation for Post Office Box.
How do you write PO Box in an address?
A basic format is:
John Smith
PO Box 123
Chicago, IL 60601
Follow the specific addressing requirements of the destination postal service when necessary.
What does PO Box stand for?
PO Box stands for Post Office Box.
Is PO Box the same as a mailing address?
A PO Box can be used as a mailing address, but the terms are not identical. A PO Box is a particular type of mailing address associated with a postal box.
Can a PO Box replace a street address?
It can serve as a mailing address in many situations, but it may not replace a street address when a form, service, delivery provider, or organization specifically requires a physical address.
Is “P.O. Box” still correct?
Yes. P.O. Box is still a correct and recognizable form of the abbreviation Post Office Box.
Is “PO. Box” correct?
No. PO. Box is not the standard form. Use PO Box or P.O. Box instead.
Is “P.O Box” correct?
No. If you use periods, the standard form is P.O. Box, with a period after both P and O.
Is “POBox” correct?
No. The correct form contains two words:
PO Box
Is “P O Box” correct?
No. The standard forms are PO Box and P.O. Box.
Is PO Box capitalized?
In a mailing address, PO Box is normally capitalized.
PO Box 123
Which is more modern: PO Box or P.O. Box?
PO Box is generally considered the more modern-looking form because it omits periods from the abbreviation.
Is PO or P.O. correct?
Both PO and P.O. are established forms. PO is the unpunctuated modern form, while P.O. is the traditional punctuated form.
Can I use PO Box in formal writing?
Yes. PO Box is appropriate in formal and professional writing. You do not need to use P.O. Box simply because a document is formal.
What is the difference between PO Box and Post Office Box?
There is no difference in meaning. PO Box is an abbreviation of Post Office Box.
Should I write PO Box or Post Office Box?
Use PO Box when you want a concise form, particularly in an address. Use Post Office Box when you want to spell out the term completely.
Can I put a PO Box and street address on the same address?
Sometimes an address may contain both types of information, but the correct format depends on the purpose of the address and the relevant postal or delivery requirements. If you are given an official address, reproduce it as provided.
Conclusion
PO Box and P.O. Box are both correct ways to write the abbreviation for Post Office Box.
The main difference is punctuation:
✅ PO Box — modern, unpunctuated form
✅ P.O. Box — traditional, punctuated form
If you are choosing a style for a modern mailing address, PO Box is a simple and clean option. If an organization or postal service provides its address as P.O. Box, you can use that format instead.
The forms to avoid are “PO. Box,” “P.O Box,” “POBox,” and “P O Box.”
Quick takeaway: PO Box and P.O. Box are both correct; the choice mainly depends on punctuation and style.
I am Emily Carter, an English grammar writer and language enthusiast dedicated to helping people improve their writing skills with simple and clear explanations. I have spent years studying English usage, sentence structure, punctuation, and common grammar mistakes. My goal is to make grammar easy for students, professionals, and everyday writers by explaining complex rules in a practical way. I believe good grammar builds confidence and helps people communicate their ideas more effectively.
I have written several educational resources, including my books “The Complete Guide to English Grammar Rules” and “Mastering English Writing: A Practical Grammar Handbook.” Through my articles and books, I continue to help readers understand English better and write with accuracy and confidence.