Choosing the right envelope size is one of the most important (and often overlooked) steps in any print or mailing project. Whether you’re sending announcements, invoices, checks, or marketing mailers, proper envelope sizing ensures a clean presentation, smooth mailing, and USPS compliance.
To make things easier, we’ve created this Envelope Sizing Guide to help you confidently select the right envelope for your project—from A-style announcement envelopes to standard correspondence sizes.
Understanding A-Style Announcement Envelopes (A2–A10)
A-style envelopes are commonly used for invitations, announcements, greeting cards, and promotional inserts. These sizes are widely available and easy to match with standard printed pieces.
Here are some of the most common A-style envelope sizes and their suggested insert dimensions:
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A2 Envelope (4.375″ x 5.75″)
Suggested insert: 4.125″ x 5.5″
Perfect for thank-you cards and small announcements. -
A6 Envelope (4.75″ x 6.5″)
Suggested insert: 4.5″ x 6.25″
A popular choice for invitations and postcards. -
A7 Envelope (5.25″ x 7.25″)
Suggested insert: 5″ x 7″
Great for event invitations and formal announcements. -
A8 Envelope (5.5″ x 8.125″)
Suggested insert: 5.25″ x 7.875″ -
A9 Envelope (5.75″ x 8.75″)
Suggested insert: 5.5″ x 8.5″ -
A10 Envelope (6″ x 9.5″)
Suggested insert: 5.75″ x 9.25″
Ideal for oversized invitations or folded letters.
Tip: Always allow a small margin between your insert and envelope to ensure easy insertion and a professional finish.
Standard Correspondence Envelope Sizes (# Series)
For everyday business mail, the # series envelopes are the industry standard. These are commonly used for letters, checks, statements, and return mail.
Common sizes include:
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#10 Envelope (4.125″ x 9.5″)
The standard U.S. letter envelope—perfect for tri-folded 8.5″ x 11″ documents. -
#9 Envelope (3.875″ x 8.875″)
Often used as a return envelope inside a #10. -
#8 5/8 Envelope (3.625″ x 8.625″)
Commonly used for checks. -
#7 ¾ (Monarch) (3.875″ x 7.5″)
A more traditional or formal option.
These sizes are readily available and work well for automated mailing systems.
Window Envelopes & USPS Placement Guidelines
When using window envelopes, accuracy matters. Proper placement ensures addresses align correctly and meet USPS regulations.
Standard window size:
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7/8″ x 4 ½”
Typical window placement:
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2″ from the right side
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1/3″–2″ from the top
Additionally, USPS automation requires strict placement of FIM and POSTNET barcodes:
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FIM location: Near the top edge of the envelope
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Barcode location: 3 7/8″ from the right side and 1/4″ from the bottom
⚠️ Important: Do not enlarge, reduce, or move FIM and POSTNET barcodes. These elements must be printed at exact sizes and locations to ensure mail is accepted and processed correctly.
Why Envelope Size Matters
Choosing the right envelope size:
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Improves first impressions
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Prevents damage during mailing
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Reduces postage issues
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Ensures USPS compliance
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Saves time and money
At Graphic Creations, we don’t just print—we help you plan your project from start to finish. From selecting the correct envelope size to ensuring your mail piece meets postal requirements, our team is here to guide you every step of the way.
Need Help Choosing the Right Envelope?
If you’re unsure which envelope size works best for your next project, reach out to our team. We’re happy to help you find the perfect fit and make sure your mail looks great and mails right—every time.