Everything You Need to Know About Envelope Sizes

You send a lot of things, but why stick with one envelope only? If your documents are different, your Envelopes must have the same tone to match them, such as wedding card invitation envelopes must be unique from the creative marketing material envelopes. The standard sizes play a significant role in creating a professional look for your office correspondence, formal letters, and everyday mailing needs. Stay with us to explore various types and envelope sizes so you can meet your needs effectively.

Why Do Envelope Sizes Matter?

The perfect envelope size ensures your documents are safe from bending, creasing, or other damage while offering a professional appearance. The postage cost is also correlated with the envelope sizes; using an inaccurate size costs you more. Also, when it comes to sorting, the consistent sizes make it easy to align things without compromising on purpose and functionality of envelopes.

Standard Envelope Sizes

Business Envelope Sizes

The business envelopes are also known as regular or commercial Envelopes. You can choose any size and flap style for your general correspondence, like invoices, statements, and checks. The most common business envelopes used in the US are #10 with pointed or contoured flaps. Look at our business envelope sizes:

• #10 (4.125" x 9.5")

• #9 (3.875" x 8.875")

• #6 ¾ (3.625" x 6.5")

Window Envelope Sizes

If you’re sending bills, statements, direct mail, or official documents, you need window envelopes. They have a transparent window on the front that facilitates displaying the recipient's address or other important information without opening them. Here are a few standard sizes for window envelopes:

• #10 Window Envelope: 4⅛" x 9½" with window size1⅛" high x 4½" wide

• #9 Window Envelope: 3⅞" x 8⅞" with window size 1⅛" high x 4½" wide

• #6 ¾ Window Envelope: 3⅝" x 6½" with window size 1⅛" high x 4½" wide

• Check Envelope: 3⅝" x 8⅝" with window size 1" high x 4" wide

• DL Window Envelope: 4.33" x 8.66" with window size 1.77" high x 3.54" wide

Announcement Envelope Sizes

Announcement envelopes are made of common paper but require decorative paper stocks that are heavier. The square flap or deep pointed flaps create an elegant appearance for your envelopes, making them an ideal choice for wedding invitations, greeting cards, small brochures, photos, and more. Here are a few standard sizes for announcement envelopes:

• A2 (4.375" x 5.75")

• A6 (4.75" x 6.5")

• A7 (5.25" x 7.25")

• A10 (6" x 9.5")

Baronial Envelope Sizes

The baronial envelopes are identified by the signature diagonal seams and pointed flaps. Their distinctive style of envelopes tells the recipient about the specialty of the message. You can give a traditional and formal touch to announcements or high-end invitations with baronial envelopes. Here are the standard sizes of baronial envelopes:

• 4-Bar (or A1): 3⅝" x 5⅛"

• 5-Bar: 4⅛" x 5½"

• 5½-Bar: 4⅜" x 5¾"

• 6-Bar: 4¾" x 6½"

• 7-Bar (or Lee): 5¼" x 7¼"

• 8-Bar: 5½" x 8⅛"

• 9-Bar: 5¾" x 8¾"

• 10-Bar: 6" x 9½"

Booklet Envelope Sizes

Booklet envelopes give you the luxury to open on the longer size like a book and have a flap on the longer dimension. You can insert multiple items inside booklet envelopes without worrying about folding them. They are an ideal choice for sending brochures, multi-page documents, photographs, sales literature, annual reports, and catalogs. Here are standard sizes for booklet envelopes:

• 6" x 9½"

• 7½" x 10½" Suitable for medium-sized magazines, policy documents, or larger brochures.

• 9" x 12" popular size for mailing standard 8½" x 11" sheets of paper unfolded, as well as contracts, proposals, and reports.

• 10" x 13" oversized option for larger or thicker materials, such as manuscripts, artwork, blueprints, or a substantial stack of letter-size documents.

Catalog Envelope Sizes

Catalog envelopes are designed for bulkier materials and open on the short side with a flap along the shorter dimensions. You can use them for sending catalogs, thick reports, magazines, and large documents. Here are a few standard sizes for catalog envelopes:

• 6" x 9": A common size for smaller catalogs, brochures, or folded documents.

• 7" x 10" A good option for slightly larger reports or magazines.

• 7½" x 10½" Popular size for various documents and marketing materials.

• 9" x 12" Perfect for mailing standard 8½" x 11" documents flat without folding, such as contracts, legal papers, and multi-page reports.

• 10" x 13" An oversized option for larger documents, artwork

• 10" x 15": Used for even larger or more voluminous items.

• 12" x 15½" Suitable for very large documents or multiple items.

Square Envelope Sizes

Square envelopes are a perfect alternative for rectangular envelopes, which help to capture attention due to their unique shape. You can use them for wedding invitations, special announcements, creative marketing material, and greeting cards. Here are standard sizes for square envelopes:

• 5" x 5"

• 5½" x 5½"

• 6" x 6"

• 6½" x 6½"

• 7" x 7"

• 7½" x 7½"

• 8" x 8"

• 8½" x 8½"

• 9" x 9"

Remittance Envelope Sizes

Remittance envelopes have deep flaps and are a bit longer than other envelopes. The flap can be pre-printed to offer significant information. You can use them for payments, reply envelopes, surveys, and donations. Here are standard sizes for remittance envelopes:

• #6 ¾ Remittance: 3⅝" x 6½" (closed size) used for personal checks, cash, receipts, and donations

• #9 Remittance: 3⅞" x 8⅞" (closed size) used as a reply envelope, fitting comfortably inside a #10 envelope.

• #6 ¼ Remittance: 3½" x 6" (closed size)

• #6 ½ Remittance: 3½" x 6¼" (closed size)

Padded Envelopes Sizes

Padded envelopes are lined with bubble wrap, which offers cushioning for fragile items. You can use them forsending CDs, electronics, jewelry, and promotional items. Here are some standard sizes for padded envelopes:

Small Sizes (for jewelry, small electronics, single CDs/DVDs, small books)

• 4" x 6"

• 4" x 8"

• 5" x 10"

• 6" x 10"

Medium Sizes (for books, documents, multiple CDs/DVDs, small apparel)

• 7.5" x 11"

• 8.5" x 12"

• 9" x 12"

Large Sizes (for larger books, photo frames, clothing, and thicker documents)

• 10.5" x 16"

• 12.5" x 19"

• 10" x 13"

USPS Priority Mail Flat Rate Padded Envelope

• 12½" x 9½"

Coin Envelope Sizes

They are small envelopes and can be used for holding small items like coins, keys, jewelry, stamps, and small parts. Here are some standard sizes for coin envelopes:

• #4: 3" x 4 1/2"

• #4 1/2: 3" x 4 7/8"

• #5: 2 7/8" x 5 1/4"

• #5 1/2: 3 1/8" x 5 1/2"

• #6: 3 3/8" x 6"

• #7: 3 1/2" x 6 1/2"

Gusset Envelope Sizes

Gusset envelopes, as the name suggests, have expandable side gussets that make them ideal for holding bulky items. You can use them for sending large documents, multiple brochures, thick reports, and samples. Here are standard sizes for gusset envelopes:

Common Inch-Based Sizes

• 9" x 12": A very popular size, often used for standard letter-size documents (8.5" x 11") without folding.

• 9.5" x 15": A slightly larger option for legal-size documents or thicker stacks.

• 10" x 13": Best for larger documents, catalogs, or reports.

• 11.5" x 14.5": Suitable for larger format documents or multiple items.

• 12" x 15.5": For very large or bulky items.

Common ISO (International Standard) Sizes

• C4 (229mm x 324mm): Designed to hold unfolded A4 paper (210mm x 297mm).

• C5 (162mm x 229mm): Designed to hold A5 paper unfolded, or A4 paper folded in half.

• C3 (324mm x 458mm): Designed to hold unfolded A3 paper.

• B4 (250mm x 353mm): Often used for larger documents or when a bit more space than C4 is needed.

• DL (110mm x 220mm): While not typically a gusset envelope, some manufacturers might offer "DL+" or similar with a small gusset for bulky A4 paper folded into thirds.

Tyvek Envelope Sizes

Tyvek envelopes are water-resistant and tear-resistant envelopes made of durable synthetic materials. You can use them for sending international mail, legal papers, important documents, and items that need more protection and durability. Here are the standard sizes for Tyvek envelopes:

Small to Medium

• 6" x 9"

• 6½" x 9½"

• 7" x 10"

• 7½" x 10½"

Common Large Sizes

• 9" x 12"

• 9½" x 12½"

• 10" x 13"

• 10" x 15"

Extra Large Sizes:

• 11½" x 14½"

• 12" x 15.5"

• 13" x 19"

Takeaways

• Envelopes are made of different materials, so choose one that aligns with your purpose.

• If you have fragile items, use padded envelopes for better protection.

• The standard sizes are ideal and easy to sort, but you can have your custom envelope size if you need.

• The practical considerations for envelope sizes include content type, postage cost, protection level, presentation, purpose, branding, and environmental impact.

Whether you need an envelope for your business needs or to send unforgettable invitations, The Packaging World is your go-to choice. We will guide you about the size, design, and branding of your envelopes properly. Contact us now and have your perfect envelope effortlessly.

Standard Envelope Size Chart

Envelope sizes follow two families: A-series (announcement) envelopes for cards and invitations, and commercial envelopes for documents. The two you will meet most often are the A7 for 5 × 7 cards and the #10 for business letters.

Envelope	Size (in)	Fits
A2	4.375 × 5.75	4.25 × 5.5 card, folded letter sheet
A6	4.75 × 6.5	4.5 × 6.25 card, 4 × 6 photo
A7	5.25 × 7.25	5 × 7 invitation or greeting card
#10 commercial	4.125 × 9.5	Letter sheet folded in thirds
6 × 9 catalog	6 × 9	Letter sheet folded in half
9 × 12 catalog	9 × 12	Unfolded letter documents
10 × 13 catalog	10 × 13	Thick unfolded document sets

Postal note: pieces over 6.125 in tall or 11.5 in wide ship at USPS large-envelope (flat) rates, not letter rates — that jump is the most common surprise in mailing budgets. The Packaging World prints custom envelopes in every size above.