Guide to Standard Envelope Sizes

Key Takeaways:

• Using standard envelope sizes offers many benefits, including compatibility with standard paper sizes, postal systems, and mail-handling equipment.
• By using standard envelope sizes, you can deliver your letters, documents, and matching accessories like folders and cards securely and professionally.
• Several factors determine the ideal envelope size, including the type and size of the letter or document, the purpose (business vs. personal use), the recipients, and the budget.

With so many envelope sizes available, it can be confusing to pick the one that fits the letter or document you wish to distribute.

To narrow down the choices, consider the type of correspondence you have. Is it a greeting card for the holiday season, a printed marketing material for high-volume mailing, or a simple thank-you note to a customer?

Next, consider the purpose of your correspondence, the distribution method, and the size and weight of the content.

If you’re unsure which size to choose, see the envelope size chart below.

Envelope Size Chart

Standard Envelope Sizes	Popular Options
Business Envelopes	#10 (4.125″ x 9.5″) A2 (4.375″ x 5.75″) A9 (5.75″ x 8.75″) A6 (4.75″ x 6.5″)
Invitation and Greeting Card Envelope	A7 (5.25″ x 7.25″) A2 (4.375″ x 5.75″) A9 (5.75″ x 8.75″) A6 (4.75″ x 6.5″)
Return Envelopes	#10 #9 (3.875” x 8.875”) #6-¾ (6.5” x 3.625”) A2 A6 A7 A9 6” x 9” 9” x 12” 10” x 13”
Remittance Envelopes	#6-¾ (6.5” x 3.625”) #9 (3.875” x 8.875”)
Oversized Envelopes (Catalog/Booklet Envelopes)	6″ x 9″ 9″ x 12″ 10” x 13”

A7 (5.25″ x 7.25″)

A7 is the matching envelope size for 5″ x 7″ postcards, greeting cards, and invitations. It is often custom-printed with holiday-themed designs to match the occasion, or logos when used for direct mail marketing.

This envelope features a gummed flap that creates a permanent seal when moistened.

#10 (4.125″ x 9.5″)

Time-sensitive notices (e.g., service disconnection), bank statements, checks, and invoices often use #10. This envelope size is also the go-to option for Z-folded brochures, flyers, and letters.

Many industries use this business envelope size because it is compatible with automated inserting machines that fold and insert paper documents, helping streamline high-volume mailings.

#10 comes with an optional feature called “window,” a transparent panel that shows a recipient’s address on the enclosed letter or document.

A2 (4.375″ x 5.75″)

A2 envelopes are suitable for a wide range of business and personal correspondence, from wedding invitations and RSVP cards to thank-you notes and printed marketing materials.

These envelopes are suitable for 4.25″ x 5.5″ invitations, postcards, and greeting cards.

A9 (5.75″ x 8.75″)

A9 provides a snug fit for 5.5″ x 8.5″ flat cards and 11″ x 8.5″ folded cards (that fold to 5.5″ x 8.5″). These two card sizes are popular options for sending holiday greetings, announcements, and party invites.

This envelope size is also popular among businesses that use postcard marketing because it meets USPS requirements for First-Class Mail, a cost-effective way to send large volumes of postcards to customers.

A6 (4.75″ x 6.5″)

A6 is another popular envelope size for greeting cards, announcements, party invites, and postcards. It provides a snug fit for 4″ x 6″ flat cards and 8″ x 6″ folded cards (that fold to 4″ x 6″).

Just like A9, A6 is also a popular envelope size used by businesses across industries because it meets First-Class Mail requirements.

This business envelope features a gummed flap that creates a permanent seal when moistened.

Remittance Envelope Sizes

Standard remittance envelopes are available in two sizes: #6-¾ (6.5″ x 3.625″) and #9 (3.875″ x 8.875″). Charities and non-profit organizations, especially when seeking donations and voluntary contributions, typically use these sizes.

They are also popular for sending invoices, billing statements, and campaign donation requests from political fundraisers.

Return Envelope Sizes

Return envelopes don’t have a single specific size. However, businesses typically use these dimensions: #10, #9, #6-¾, A2, A6, A7, A9, 6” x 9”, 9” x 12”, and 10” x 13”.

Despite being available in a wide range of sizes, all return envelopes have the sender’s address pre-printed, allowing recipients to mail something back to the sender. In some cases, they also include postage, so recipients can send them back without buying their own postage stamps.

In essence, they simplify the process of returning documents, forms, and payments.

Oversized Envelope Sizes

Oversized envelopes are often used to distribute booklets, catalogs, brochures, annual reports, branded wall calendars, and other large print materials. The most popular sizes are 6″ x 9″, 9″ x 12″, and 10″ x 13″.

There is an option to order oversized envelopes with their flaps on the short side, giving them a portrait or vertical orientation.

---

Choosing the right envelope size for your print materials offers many benefits, including lower costs, compatibility with standard paper and card sizes, and a professional appearance. The right size also provides adequate protection and allows the content to fit snugly.

NextDayFlyers offers various types of envelopes suitable for high-volume mailings, marketing materials, formal correspondence, and personal use.

These envelopes are highly customizable; you can print your logo or artwork so they reflect your brand or match the occasion or message.

Aside from custom printing, you can also add special features like windows or transparent panels and square-shaped flaps. Oversized envelopes (like 6″ x 9″, 9″ x 12″, and 10″ x 13″) even let you place the flaps on their short side for a more modern design.