Envelope Format


November 13, 2023

Fewer Americans are writing and sending letters through the mail.

While the birth of the internet is a significant factor contributing to the decline of sending letters via the Postal Service, other factors, such as the hassle of buying stamps and meeting strict packaging and addressing guidelines, also play a role.

However, knowing someone took the time and effort to send a letter to your mailbox paradoxically makes receiving one so endearing. It’s one of the reasons snail mail is still alive and well.

Whether it’s a heartfelt, handwritten letter to a loved one or essential documents for a business negotiation, knowing the appropriate envelope to put your mail in is vital in ensuring it reaches its intended recipient.

This article tackles envelope formats, from the various sizes and styles to proper addressing and making your own. To make your letter-sending experience even more convenient, visit FindPostOffice.org.

With over 31,000 post office locations across the United States, finding a convenient facility to send your letter through can be overwhelming. Fortunately, our post office locator tool lets you narrow down potential facilities. 

What Is the Format of an Envelope?

An envelope is more than just a piece of paper covering your letters or greeting cards. It’s part of an organized system that ensures your mail gets to its intended destination correctly and on time.

While envelopes come in different shapes and sizes, the format of a standard envelope generally consists of three essential elements: the sender’s address, the recipient’s address, and the postage stamp.

Here’s how it looks like:

Sender’s Name
Sender’s Street Address/#
Sender’s City, State Zip Code
Postage Stamp
Recipient’s Name
Recipient’s Street Address/#
Recipient’s City, State Zip Code

The sender’s address or return address helps the United States Postal Service (USPS) and other carriers return the mail to you if any delivery issues occur, such as if no one at the delivery address receives the envelope.

The recipient’s address ensures that the Postal Service and couriers can successfully deliver your mail to your intended recipient. On the other hand, the postage stamp proves that you’ve paid for the delivery of the mail item.

How to Address an Envelope

Addressing an envelope is a straightforward process:

  • You write your name and address information
  • You write the receiver’s information, including their mailing address
  • Stick a stamp on the envelope
  • Put your mail in the mailbox, or drop it off at a USPS box or facility

While addressing envelopes may seem tedious, it’s a critical step that’s as important (if not more) as writing the letter you’re putting inside.

Why Is It Important to Address an Envelope Correctly?

Correctly addressing an envelope is crucial for several reasons. Here are some of them:

  • Ensures delivery: The address format on an envelope ensures your letter reaches its proper destination. If you don’t correctly address your envelope, the Postal Service may experience delivery delays or lose your mail in transit.
  • Shows professionalism: Using the correct address formats in your business envelopes reflects your professionalism and attention to detail, which are essential for business correspondence and help convey respect and consideration for the recipient.
  • Increases brand awareness: Envelopes can serve as a branding opportunity, allowing your brand and message to stand out. They visually represent who you are as an individual or a business.
  • Saves time: Correctly formatted addresses allow postal workers to process mail more efficiently. Ensuring that every piece of mail you send out follows the Postal Service’s format reduces the chances of re-sending or re-routing.

Address Format Tips

To ensure the correct format of an address and the smooth delivery of your letter, you must keep the following tips in mind:

  • Use standard envelope sizes: You must choose an envelope that fits the size of your mail appropriately. Fortunately, the Postal Service eliminates the guesswork by offering free shipping supplies, including standard-size envelopes. If you’re using your own envelopes, ensure they meet your carrier’s size requirements.
  • Follow the address format guidelines: When writing addresses, you must follow the proper formatting guidelines, including the order of the apartment or suite number, street address, city, state, and ZIP+4 code. Ensure you print all the mailing information on one side of the envelope.
  • Write the mailing information legibly: To avoid misinterpretations, clearly print your and the recipient’s address using legible fonts. Write the addresses in capital letters, use permanent ink, include postal service abbreviations for states, avoid using commas and periods, and have the ZIP+4 code.

Read the Postal Service’s addressing standards for more information on properly addressing an envelope. Alternatively, you may seek assistance from a USPS representative at your local postal, which you can find by visiting FindPostOffice.org and using the facility locator tool.

Write Sender Address

To begin addressing an envelope, write your full name or company name, your apartment or suite number on the following line, then the street address, city, state, and ZIP code.

You must place this essential information in the top-left corner of the envelope. Doing so allows the Postal Service to return the mail to you if necessary.

Your address should look like this:

ANY CITY NY 12345-6789
Postage Stamp

Write Delivery Address

At the bottom center of the envelope, write the recipient’s full name, followed by their street address, city, state, and ZIP code. Ensure you use the appropriate abbreviations for the state and include the correct address.

The recipient’s mailing information should look similar to this:

Postage Stamp
CITYVILLE CA 98765-4321

Special U.S. Addresses

Addressing envelopes may differ for specific U.S. addresses. Here are some important considerations:

Puerto Rico

If the Puerto Rico address includes an urbanization or community code, write it following the recipient name line and abbreviate it as URB. Ensure that you also use the abbreviation for Puerto Rico (PR).

The envelope format should follow this:

Postage Stamp
SAN JUAN PR 12345-6789

U.S. Virgin Islands

Addresses in the U.S. Virgin Islands follow the Postal Service’s standard address format but use the abbreviation “V.I.” for the state.

Use this format when addressing an envelope to the U.S. Virgin Islands:

Postage Stamp
CRUZ BAY, VI 98765-4321

Military and Diplomatic Mail (APO/FPO/DPO)

When sending mail to the Army Post Office (APO), Fleet Post Office (FPO), and Diplomatic Post Office (DPO), you must follow specific addressing guidelines, including:

  • Omitting the city or country name
  • Stating the unit number, followed by the box number
  • Indicating the appropriate post office designation (APO, FPO, DPO), and the two-letter state abbreviation (A.A., A.E., A.P.)
    • Use “A.A.” for the Armed Forces of America
    • Use “A.E. for the Armed Forces of Europe
    • Use “A.P.” for the Armed Forces of the Pacific

Follow this format:

Postage Stamp
UNIT 123456 BOX 7890
FPO AA 98765

If you need a more comprehensive guide on sending a letter to a military or diplomatic address, visit USPS’ official website. You may also use FindPostOffice.org’s post office locator tool and inquire in person.

How to Write an International Shipping Address

The guidelines for addressing envelopes for international shipping are relatively the same as domestic mailing. The only difference is that you include the destination country on the last line.

Postage Stamp

Some countries may have different variations, such as placing the ZIP code in front of the city and country. It would be best to check the specific addressing requirements for the destination country.

How to Find the “ZIP+4” Code

The ZIP+4 is a nine-digit code that USPS uses to identify a location within a delivery area. The first five digits refer to the ZIP code of a specific shipping area, while the last four digits, or the “+4,” identify a smaller zone within that delivery area.

If you need help with the ZIP+4 code, use USPS’ ZIP code lookup tool. It lets you identify the ZIP code using a corporate or street address, city, or state and see a list of delivery areas within a ZIP code.

You can also speak to a Postal Service representative at a local post office if you need help finding ZIP+4 codes. Narrow down the list of USPS facilities in your area by visiting FindPostOffice.org.

Writing an Envelope Checklist

To ensure you address an envelope accurately, use this handy checklist:

  • Include your name and complete address in the top left corner
  • Write the recipient’s full name and address in the bottom center of the envelope
  • Use clear and legible fonts
  • Use the appropriate envelope size for your mailing
  • Research and follow any specific address formats for special U.S. addresses or international shipping
  • Include necessary suite or apartment numbers
  • Double-check the address for accuracy and completeness
  • Use standard Postal Service abbreviations
  • Ensure you securely seal the envelope before mailing

Common Envelope Sizes

Envelopes come in various sizes, each suitable for different types of correspondence. Here are some common envelope sizes and their uses:

Booklet Envelopes Sizes

With their sturdy construction, side seam, or open-side design, booklet envelopes are an excellent option if you need to send bulkier or thicker documents, such as catalogs, annual reports, or brochures.

Booklet envelopes come in various sizes, which include:

5 ½” x 7 ½” 5 ½” x 8 ⅛” 5 ½” x 8 ½” 6” x 9”6” x 9 ½” 
6 ½” x 9 ½” 7” x 10”7 ½” x 10 ½” 8 ¾” x 11 ½” 9” x 12”
9 ½” x 12 ⅝” 10” x 13”10” x 15”

Square Flap Envelopes

As its name implies, a square flap envelope has a square-shaped flap on its back that acts as a seal. Choose a square flap envelope if you send invitations, such as birthday or wedding invitations, greeting cards, announcements, and photos.

Common square flap sizes include the following:

2 ⅞” x 6 ½”3 ⅝” x 5 ⅛” 3 ⅞” x 8 ⅞”4 ⅛” x 9 ½”4 ¼” x 6 ¼” 
4 ⅜” x 5 ¾”4 ¾” x 6 ½”5 ¼” x 7 ¼” 5 ½” x 8 ⅛”6” x 9 ½”

Contour Flap Envelopes

Featuring a triangular flap that’s as almost as tall as the envelope itself, contour flap envelopes are also an option if you send invitations, announcements, or greeting cards.

Contour flap envelopes come in the following sizes:

3 ⅝” x 5 ⅛”4 ¼” x 6 ¼”4 ⅜” x 5 ¾”4 ¾” x 6 ½” 5 ¼” x 7 ¼”
5 7/16” x 7 ⅞” 5 ¾” x 8 ¾”6” x 9”6 ½” x 6 ½”

Regular Envelopes

When it comes to standard envelope formats, the regular envelope is your go-to option. You can use a regular envelope if you send invoices, checks, and letter writings, as it typically has adhesive flats for privacy and security.

Regular envelopes come in the following sizes:

2 ⅛” x 3 ⅝” 3” x 6 ¼”3 ½” x 6”3 ⅝” x 6 ½”
3 ⅚” x 8 ⅝” 3 ¾” x 6 ¾”3 ⅞” x 7 ½”3 ⅞” x 8 ⅞”
4 ⅛” x 9 ½”4 ½” x 10 ⅜”4 ¾” x 11”5” x 11 ½”

Window Envelopes

There are several variations of window envelopes, which include single, double, and full-face windows. Depending on the size of the transparent sheet, these envelopes allow you to show a portion or most of the content inside.

Some window envelopes also have a transparent sheet over the return or recipient address, eliminating the need to write the addresses on the envelope. Generally, the size of a window envelope is 5 ¾ x 8 inches.

Square Envelopes

While square envelopes also feature a square-style flap on the back, similar to square-flap envelopes, they’re generally a symmetrical square shape.

Still, square envelopes are a good choice for postcards and photos, as they also come in various sizes that include the following:

3 ¼” x 3 ¼”5” x 5”5 ½” x 5 ½”5 ¾” x 5 ¾”6” x 6”
6 ½” x 6 ½”7” x 7”7 ½” x 7 ½”8” x 8”8 ½” x 8 ½”
9” x 9”9 ½” x 9 ½”10” x 10”

Open-End Envelopes

Catalog or open-end envelopes allow you to easily place and remove mail items from them, as their flap is at the short end. Open-end envelopes come in small sizes for coins and jewelry, regular sizes for mail and letters, and jumbo to accommodate more oversized items like catalogs and booklets.

The range of sizes for catalog envelopes is as follows:

2 ¼” x 3 ½”2 ½” x 4 ¼”3” x 4 ½” 3” x 4 ⅞”3 ⅛” x 5 ½”
3 ⅜” x 6”3 ½” x 6 ½”3 ⅝” x 6”4 5/16” x 9 9/164 ½” x 10 ⅜”
4 ⅝” x 6 ¾”5” x 4 ⅞”5” x 7 ½”5” x 11 ½”5 ½” x 7 ½” 
6” x 9”6” x 11 ½”6 ½” x 9 ½”7” x 10”7 ½” x 10 ½”
8 ½” x 10 ½”8 ¾” x 11 ¼”9” x 12”9 ½” x 12 ½”10” x 13”
11” x 17”11 ½” x 14 ½”12” x 15 ½”12 ½” x 18 ½”14” x 18”

Clasp Envelopes

Like open-end envelopes, clasp envelopes are good options for bulkier mail items. What sets clasp envelopes apart from their open-end counterpart is the presence of a metal clasp to keep the envelope secure.

Available sizes for clasp envelopes include the following:

6” x 9”6 ½” x 9 ½”7” x 10”7 ½” x 10 ½”
9” x 12”10” x 13”10” x 15”

Document Envelopes

If you’re sending flat but bulky items, such as magazines, catalogs, or other large stacks of paper, you can use a document envelope. These envelopes have a 3-inch wide flap to allow easy access to the contents.

Sizes for document envelopes include:

9” x 12”10” x 13”
10” x 15”12” x 18”

Remittance Envelopes

Donation or remittance envelopes offer a unique design that allows for currency collection thanks to their large flaps. Choose a remittance envelope when collecting payments, such as for charity, fundraising, or church offerings.

Remittance envelopes are available in a variety of dimensions to suit different needs, which include:

3 ½” x 6”3 ⅝” x 6 ½” 3 ⅞” x 8 ⅞” 
4 ¼” x 6 ½” 4 ⅝” x 8 ⅞” 

Pointed Flap Envelopes

Pointed flap envelopes are the best option if you want a classic envelope look. Unlike counter flap envelopes, pointed flap envelopes have reasonably sized flaps with crisp edges.

Regardless of the occasion, you have a variety of size options, which include:

3 ⅝” x 5 ⅛” 4 ⅛” x 5 ½” 4 ⅜” x 5 ¾” 4 ¾” x 6 ½” 5 ¼” x 7 ¼” 
5 ¼” x 7 ½” 5 ½” x 7 ½” 6” x 8 ¼” 6 ¼” x 8 ½” 

Mini Envelopes

“Small in size, big in style,” mini envelopes are the perfect solution when you require an envelope for small or flat cards, such as seating, place, greeting, or business cards.

While relatively smaller than other standard envelopes, mini envelopes still come in various dimensions, including the following:

2 ½” x 4 ¼” 2 11/16” x 3 11/163” x 4 ½” 

Lined Envelopes

A lined envelope features a lining extending from its flap to its insides. This envelope type is perfect for sending wedding invitations, greeting cards, or special letters.

Common sizes for lined envelopes are as follows:

4 ⅜” x 8 ¼” 5 ¾” x 8 ¾” 

Specialty Use Envelopes

Choose specialty use envelopes if you require a container for specific purposes, like storing flight itineraries, boarding passes, or jewelry. Generally, they come in dimensions of 3 ⅞ x 8 ½ inches. 

Folded Cards

While people typically use them as response cards or creative outlets, folded cards are versatile. You can personalize your envelope with letterheads, logos, and designs on a blank canvas.

Depending on your needs, folded cards come in various sizes, which include:

2 9/16” x 3 9/163 ½” x 4 ⅞” 4 ¼” x 5 ½” 4 ¼” x 6”4 4/8” x 6 ¼” 
5” x 7” 5 ⅛” x 7”5 ½” x 8 ½”6 ¼” x 6 ¼” 


The sturdy construction of notecards increases their longevity and makes them suitable for greeting cards or invitations. Like folded cards, notecards are blank canvases, offering a chance for personalization.

Some of the popular notecard dimensions include:

2” x 3 ½” 2 9/16” x 3 9/163 ½” x 2”3 ½” x 4 ⅞” 4” x 6”
4 ¼” x 5 ½” 4 ⅝” x 6 ¼” 4 ¾” x 4 ¾” 4 ⅞” x 7”5 ⅛” x 7
5 ½” x 8 ½” 5 ¾” x 5 ¾” 6 ¼” x 6 ¼” 

Vertical Square Flap Envelopes

Unlike standard square flap envelopes, vertical square flap envelopes have a horizontal orientation. These envelopes are perfect if you send invitations, greeting cards, announcements, or photos in a portrait format. Vertical square flap envelopes come in a size of 5 ¼ x 7 ¼ inches.  


Whether you’re creating small greeting cards, restaurant menus, or business cards, cardstocks can be a viable option. These blank envelopes let you be creative and add personality to your correspondence.

Cardstocks are available in the following sizes:

4 3/16” x 5 7/168 ½” x 14”11” x 17”12” x 12”


If you need something to write on or create your envelope, paper is one of the most versatile materials.

Standard paper sizes include:

4” x 6”4 3/16” x 5 7/165” x 2”5” x 7”
8 ½” x 14”11” x 17”12” x 12”

Wedding Favors

A wedding favor is a small label you can attach to gift items or envelopes for guests as thanks for attending a wedding celebration. You can customize wedding favors to include special messages.

While wedding favors can have a custom size, they generally come in the following standard dimensions:

1” x 1”2” x 2”3” x 3”
4” x 4”2” x 3 ½” 2” x 4”

All-Purpose Window Envelopes

If you want to eliminate the need for separate labels, you can use an all-purpose window envelope, which features a large viewing window on the front. The envelope’s dimensions are 4 ⅛ x 9 ½ inches.

Double Window Envelopes

Standard window envelopes have one window. Meanwhile, double window envelopes have two, one on the top and one on the bottom. These viewing screens display the sender’s and the recipient’s address information.

Double window envelopes sizes generally include:

3 ⅝” x 8 ¾” 4 3/16” x 9”

Thumb Cut Envelopes

A thumb cut envelope has a small cut-out or notch on its side, allowing you to quickly retrieve its contents, like checks, invoices, or other documents you need to open and close frequently. The standard thumb-cut envelope size is 2 ⅜ x 3 ½ inches.

Full-Face Window Envelopes

Full-face window envelopes feature an oversized transparent screen on the front of the envelope, which displays the entire content. These envelopes are best for catalogs, account statements, or other documents that require a visible address.

Common sizes for full-face envelopes include the following:

4 ⅛” x 9 ½” 6” x 9”9” x 12”9 ½” x 12 ½”  

Blank Standard Presentation Folders

If you need a sturdy envelope to mail brochures, reports, and other personal and professional documents, consider using a blank standard presentation folder.

The distinct feature of this envelope type is that it includes interior pockets on either flap, giving you ample space to store and secure your mail items. These envelopes are unique because they have pockets inside to store your mail items.

Depending on the documents you’re putting inside, sizes for presentation folders include:

9” x 12”9” x 14 ½” 6” x 9”

Expansion Envelopes

If your mail items, such as books or financial reports, are too large for standard envelope sizes, expansion envelopes are the perfect solution. These envelopes feature an accordion-folded side panel, allowing it to expand from one to four inches.

Common sizes for expansion envelopes include:

10” x 13” x 1 ½” 10” x 13” x 2”10” x 15” x 2”

Poly Mailers

Poly mailers are lightweight, weather-resistant envelopes that are made with polyethylene. Use poly mailers to avoid moisture damage to your documents, apparel, or pharmaceuticals. The envelope’s size is generally 10 x 13 inches.

Spot Seal

While not an envelope, a spot seal is what you use to close envelopes. These are small adhesives that you apply to specific spots on an envelope to secure and protect the contents inside.

LUX Mailers

LUX mailers don’t refer to a specific envelope type, like spot seals. Instead, LUX is a brand that offers mailing supplies, including envelopes. The standard dimensions for a LUX mailer are 9 ½ x 12 ½ inches.

Single Window Envelopes

A single-window envelope is a mailing envelope with a transparent window for the recipient’s address. While using a single-window envelope eliminates the need to print the recipient’s information, you still must write your return address.

The common dimensions for single-window envelopes include the following: 

3 ⅝” x 6 ½” 3 ⅝” x 8 ⅝” 3 ⅞” x 8 ⅞” 4 ⅛” x 9 ½” 4 ½” x 9 ½” 
4 ½” x 10 ⅜” 5” x 11 ½” 6” x 9”9” x 12”

Is There an Envelope Template in Word?

Microsoft Word has envelope templates you can print and use to send your letters or documents. To create an envelope using Microsoft Word, follow these steps:

  • Open the “Mailings” tab
  • Click the “Envelope” button
  • Input the sender and the recipient’s mailing information, following the Postal Service’s addressing format and guidelines
  • Click the “Options” button to select your envelope size, customize your fonts, and adjust the location of the addresses.
  • Finally, click the “Print” button.

How Many Stamps Should You Use?

The number of postage stamps you must attach to your envelope depends on your parcel’s weight and size and the receiver’s location. Generally, standard envelopes that weigh 3.5 ounces or less use one stamp.

On the other hand, you must use two stamps for the first ounce of a large envelope, which includes 9” x 12” and legal envelopes. If you’re sending an envelope internationally, you’ll need a forever stamp, which the USPS issues for mail weighing an ounce or less.

For more information on postage stamps, visit USPS’ official website. A post office representative can also answer your questions. Use FindPostOffice.org’s facility locator tool to find your area’s most convenient locations.


  1. Most Americans haven’t written a personal letter on paper in over five years
  2. Envelope Format
  3. How to Send a Letter or Postcard: Domestic
  4. Envelopes
  5. How Do I Address Military Mail?
  6. USPS ZIP Code Lookup
  7. Envelope Sizes
  8. Envelope Size Charts
  9. LUXPaper 9″ x 12″ Presentation Folders
  10. Presentation Folders
  11. Envelope Seal
  12. LUX Poly Bags
  13. How to Print Envelopes in Word
  14. How many stamps do I need? And where to buy?
  15. Forever Stamp Fact Sheet
  16. USPS Forever Stamps, First Class Stamp