Understanding Envelope Sizes

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Whether you’re sending custom invitations, letters to donors or corporate communications, understanding envelope sizes can be a big help. After all, envelopes are part of your marketing package, making that all-important first impression.

As a premium online printer, Onestopdp offers more than just standard envelope sizes, so you can conveniently mail anything with the right look, from professional to personalized.

Personal & Event Envelopes

When you think custom envelopes, you think events. From birthdays and anniversaries to weddings, fundraisers, galas and more, envelopes for announcements and cards are a must. With onestopdp, you can design and print your own envelopes to suit any occasion.

A1 (3.625” x 5.125”)

Very common envelope size for the traditional 3.5” x 5” RSVP cards
Flap type: Tapered
Flap dimensions: 1.5-1.81″H x 5.125″W

A2 (4.375” x 5.75”)

Fits any card or invitation sized up to a 4.25” x 5.5”
Common for invitations, greeting cards, thank you cards
Designed for letters that are quarter-folded
Flap type: Tapered
Flap dimensions: 1.75-2.25″H x 5.75″W

A6 (4.75” x 6.5”)

Fits any card or invitation sized up to a 4.5” x 6.25”
Great for traditional-sized wedding invitations and save the date cards
Flap type: Tapered
Flap dimensions: 2.06-2.5″H x 6/5″W

A7 (5.25” x 7.25”)

Fits any card or invitation sized up to 5” x 7”
Commonly used for the outer (mailer) envelope for wedding invitations
Flap type: Tapered
Flap dimensions: 2.125-2.5″H x 7.25″W

Business & Corporate Envelopes

No matter the size of your business or organization, business stationery is essential, and that includes envelope printing. Perfect for sending updates to donors, communication to employees, direct mail marketing and more, these envelope sizes help you send the right message.

#6-3/4 Remittance Envelope (3.625” x 6.5”)

Maximum enclosure size: 3.375” x 6.25”
Donation envelopes used for fundraising, money collection and charity donation
Sizable flap allows for printing on the inside
Flap type: Tapered
Flap dimensions: 3.437″H x 6.5″W

#9 Envelope (3.875” x 8.875”)

Maximum enclosure size: 3.625” x 8.625”
Commonly used for reply envelopes and sending money or donations
Flap type: Tapered
Flap dimensions: 1.875″H x 8.875″W

#9 Remittance Envelope (3.875” x 8.875”)

Maximum enclosure size: 3.625” x 8.625”
Commonly used for reply envelopes and sending money or donations
Sizable flap allows for printing on the inside
Flap type: Tapered
Flap dimensions: 3.687″H x 8.875″W

#10 Envelope (4.125” x 9.5”)

Maximum enclosure size: 3.875” x 9.25”
Commonly paired with a tri-fold letter
Popular business envelope for traditional and direct mail
Flap type: V-shape
Flap dimensions: 1.875″H (at V point) x 9.5″W

#10 Window Envelope (4.125” x 9.5”)

Maximum enclosure size: 3.875” x 9.25”
Commonly paired with a tri-folded letter
Popular corporate envelope for traditional and direct mail
Typically used to display the recipient’s mailing address through the window opening
Flap type: Tapered
Flap dimensions: 1.5″H x 9.5″W

#10 Window Security Envelope (4.125” x 9.5”)

Maximum enclosure size: 3.875” x 9.25”
Commonly paired with a tri-folded letter
Popular business envelope for traditional and direct mail
Typically used to display the recipient’s mailing address through the window opening
Includes a tinted pattern inside the envelope that reduces visibility of seeing sensitive information through the envelope itself
Flap type:
Flap dimensions: 1.875″H (at V point) x 9.5″W

Common Catalog & Booklet Envelope Sizes

For many who make online printing part of their marketing strategy, custom booklets are important promotional pieces. Whether you send product catalogs to customers or mail annual reports to shareholders, slip them into an envelope for protection.

These envelope sizes also make it easy to include inserts like business cards, brochures and other marketing collateral.

6×9 Open Side Envelope

Maximum enclosure size: 5.75” x 8.75”
Commonly used for mailing documents, letters and reports that are folded in half
Flap type: Tapered
Flap dimensions: 1.5″H x 9″W

6×9.5 Open Side Envelope

Maximum enclosure size: 5.75” x 9.25”
Commonly used for mailing documents, letters and reports that are folded in half
Flap type: Tapered
Flap dimensions: 1.5″H x 9.5″W

9×12 Open Side Envelope

Maximum enclosure size: 8.75” x 11.75”
Great for mailing flat documents, booklets and reports
Flap type: Tapered
Flap dimensions: 1.437″H x 12″W

10×13 Open Side Envelope

Maximum enclosure size: 9.75” x 12.75”
Great for mailing flat documents, booklets and reports
Flap type: Tapered
Flap dimensions: 1.5″H x 13″W

Envelope Sizes & Inserting

As part of our wide range of online printing services, we can insert printed pieces (letters, cards, invitations, etc.) into envelopes for you. This can be especially helpful and save you time for direct mailings and business or corporate communications.

Please note:

Any printed piece that gets inserted by machine must be 1/2″ shorter in width and 1/4″ shorter in height than the envelope.
If your piece does not follow these guidelines, it must be inserted by hand, which includes additional fees and extends turnaround time.

For envelope mailing information, visit Mailing Design Guidelines. If you have questions about envelope sizes, please contact customer service.