First impressions count. A flimsy envelope can hurt your brand more than help it. When it comes to business communication, the way documents are presented can make a big difference.
Envelopes are an often-overlooked detail. Did you know that historically, they were a symbol of status among the wealthy? Over time, envelopes became the standard method for packaging and sending correspondence. Today, they are a regular part of our daily business and personal communication.
There are many options available. Understanding the different business envelope sizes and formats can help you choose the right one for each requirement.
What are the most common business envelope sizes? What should I stock for my company?
The most common business envelope sizes are #10 for standard letters, #9 for return envelopes inside #10s, A6 for personal notes and invitations, and 9″ x 12″ catalog envelopes for larger documents. Stocking these four types of envelopes will keep you covered for everyday business correspondence, promos, or larger mailing needs.
#10 Envelope (4.125″ x 9.5″)
The #10 envelope is the workhorse of business mail. It’s the most commonly used envelope size, particularly for sending standard-sized letters and documents. It is the perfect envelope for sending an 8.5” x 11” sheet of paper folded into thirds, which is the standard size for most office documents.
A popular size for:
- Business letters
- Professional correspondence
- Invoices
- Bills
- Contracts
- Agreements
Fun fact → #10 is the envelope size most often used by direct mail marketers and is the most commonly found in the offices of businesses across various industries.
#9 Envelope (3.875″ x 8.875″)
The #9 envelope is smaller than the #10 – it can be used for return mail or reply envelopes. It typically fits inside a #10 envelope and is commonly used in direct mail campaigns.
When to Use:
- Reply mail
- Smaller documents
- Direct mail campaigns
Why use it → The #9 envelope is a practical choice for return mail or when you need to include a smaller document in a larger mailing. It’s compact and cost-effective – ideal for high-volume mailings.
A6 Envelope (4.75″ x 6.5″)
An A6 envelope is a bit smaller than the #10 and is often used for personal or promotional mail, such as invitations or greeting cards. It’s not the most common for business letters, but it can be perfect for special occasions or events. Often used in corporate settings to send thank-you notes, special invitations, or event materials.
Popular uses include:
- Invitations to corporate events
- Thank-you cards
- personal notes
- Postcards
- Announcements
For personal messages → The A6 envelope is ideal for sending slightly smaller materials than the traditional letter-size documents. Need to convey a personal message or invite clients to a special event? Go with the A6 size. It works well because it’s compact, easy to manage, and stands out visually due to its smaller size.
A7 Envelope (5.25″ x 7.25″)
The A7 envelope is commonly used for sending 5″ x 7″ cards, invitations, and brochures. It’s another envelope option often used for events, promotions, or personal notes. Although it’s not typically used for business letters, the A7 is often used by businesses for creative or personal marketing purposes.
Businesses use them for:
- Invitations (company events, conferences, and galas)
- Greeting cards
- Thank-you notes
- Promotional materials like brochures
Elegant campaigns → The A7 envelope has a bit more space than the A6 and can comfortably fit larger cards and promotional materials. It adds a touch of elegance to invitations or other marketing materials. If you need a professional yet distinctive envelope for a high-impact communication piece, the A7 is a solid choice.
Catalog Envelopes (9″ x 12″ and Larger)
Catalog envelopes, such as the 9″ x 12″ size, are larger envelopes used primarily for catalogs, brochures, and other large documents. These envelopes can comfortably hold documents that are unfolded or documents that are folded once, without causing creases. Catalog envelopes are most often used by businesses that deal with marketing materials or need to send bulk documents to clients.
Use for:
- Catalogs, brochures, and marketing kits
- Large contracts or proposals
- Legal-sized documents
The best for large items → Larger, non-foldable objects are ideal for mailing in catalog envelopes. The catalog envelope is the best fit if you need to distribute presentations, brochures, or marketing materials that can’t be folded.
Window Envelopes (#10 Window) (4.125″ x 9.5″)
Window envelopes are a variation of the #10 envelope and are commonly used for business mail, especially when documents include a pre-printed address. The “window” shows the address and removes the need for additional address labeling.
When to use:
- Invoices and billing statements
- Pay stubs and financial correspondence
- Official notifications (government or legal)
Best for invoicing → It is great for saving time and is used extensively in businesses where bulk mail with pre-addressed documents is common, such as sending invoices or official notifications.
Baronial Envelopes (4.875″ x 6.75″)
Baronial envelopes are similar in size to the A6, but they have a more traditional and formal look. Often used for personal or high-end business correspondence. Add a touch of elegance to invitations or business cards with the pointed flap at the back of the envelope. It gives it an elegant, vintage appeal.
Best used for:
- Formal invitations
- High-end business or personal letters
- Premium business communication materials
A sophisticated option → If you’re looking to convey exclusivity or professionalism, these envelopes can give your communication that extra touch of style. They’re often used in more upscale or high-end industries, such as law firms, finance, high-end fashion, or exclusive events.
Large Announcement Envelopes (6.5″ x 9.5″)
6 ½ x 9 ½ envelopes are ideal for folding a standard 8 ½ x 11″ sheet in half, making them a great choice for formal business mailings, event promotions, or announcements. They’re commonly used for company galas, fundraisers, retreats, and other events where you need to send folded letters, programs, or larger inserts without creasing.
This size is not typically used for wedding or save-the-date invitations—those are better suited to smaller A6 or A7 envelopes. However, the 6 ½ x 9 ½ envelope delivers a clean, professional look when you’re sending documents that need to impress.
Top uses:
➔ Corporate or nonprofit event invitations
➔ Folded letters, brochures, or programs
➔ Formal business announcements
For an elegant touch → This envelope size offers ample space for premium paper stock and helps your mailing feel polished and substantial—perfect for professional events and promotional campaigns.
Key Takeaways:
- #10 envelopes are perfect for sending letter-sized documents folded into thirds.
- #9 envelopes are the best option for reply mail and typically fit inside #10 envelopes!
- A6 envelopes – ideal for sending personal notes, invitations, and promos.
- A7 Envelopes have extra space for larger cards and brochures.
- Catalog Envelopes (9″ x 12″) are perfect for sending larger, unfolded documents like catalogs and proposals.
- Windowed envelopes eliminate the need for extra labels and show the address on the document – best for invoices and official notifications.
Letter Jacket Envelopes – Correspondence for Every Occasion
The right envelope can make a big difference in how your message is received. Now that you know the most common business envelope sizes and their uses, you can make the best choice for your business mailing.
Letter Jacket Envelopes understands the power of a first impression. With over 65 years of experience, we provide professional mailing solutions for everyday business needs and special occasions alike.
Explore our envelope sizes and styles to help you make a lasting impression. Visit the shop today.
