A9 Envelope Size and Guidelines

A9 Envelope Size

Sometimes, the envelope can be just as beautiful as the card homemade card enthusiasts send through the mail. But other than looks, it’s important to find an envelope that perfectly fits the type of card you use. So, if you’re wondering what size an A9 envelope is, you’ll find the answer here.

An A9 envelope measures 5-3/4 × 8-3/4 inches (146 × 222 millimeters) in size and perfectly fits A9 cards or half-folded sheets of paper. A9 envelopes are mostly used for sending announcements and invitations.

You can find A9 envelopes in a multitude of styles, including square flaps and contour flaps. You can learn more about A9 envelopes in the following sections.

A9 Envelope and Card Sizes

When it comes to announcement envelopes, you can generally pick between six size options—A1, A2, A6, A7, A9, and #10. You should know that the higher the number following the A, the larger the envelope and the size of the sheet of paper.

So, as the second-largest announcement envelope size, A9 paper will measure 5-3/4 × 8-3/4 inches (146 × 222 millimeters), which is perfect for A9 cards that measure 5-1/2 × 8-1/2 inches (140 × 216 millimeters).

There are two types of A9 cards that you can choose, which are A9 flat and A9 folded. A9 flat cards measure 5-1/2 × 8-1/2 inches, whereas A9 folded cards are 8-1/2 × 11 inches (140 × 279 millimeters), which can be folded in half to measure 5-1/2 × 8-1/2 inches. Whichever type of A9 card you choose, it will fit inside of an A9 envelope perfectly.

Why Choose A9 Cards and Envelopes?

While you can choose any card and envelope size for any purpose, homemade card enthusiasts will know that A9 cards typically serve a specific number of purposes. You will mostly find A9 cards used to send invitations (wedding, birthday, baby shower, etc.), greeting cards, bulletin announcements, greeting cards, and thank you notes.

Regardless of what you use an A9 card for, it should be sent inside an A9 envelope since A9 envelopes will leave the least amount of space inside after inserting the card. However, if you’re in a pinch, you could certainly use A9 envelopes to house A7 or A8 cards, but they will not fit together perfectly.

A9 Envelope Styles

Like any envelope, A9 envelopes come in a multitude of styles. Finding the right style for your homemade cards isn’t too difficult, as long as you are familiar with what options are available to you.

Natural Envelope

Amazon Basics A9 Blank Invitation Envelopes

The natural envelope, such as the Amazon Basics A9 Blank Invitation Envelope, doesn’t offer much in terms of aesthetics. It comes with a standard trapezoid flap that extends to roughly one-third the width of the envelope and comes with a large blank empty canvas on the front for your postage and sender details.

Colorful Envelopes

Sodaxx 60 Packs A9 5.75 x 8.75 Inches Colorful Invitation Greeting Card Envelopes

While not exactly a “style” of envelope, colorful envelopes come in a wide range of different exterior colors. Using a specific color when sending your invitations or announcements is a great way to draw the recipient’s attention. Sodaxx has a great 60-envelope pack that includes envelopes in 15 different colors.

Contour Envelopes

LUXPaper A9 Invitation Envelopes

A contour envelope is a type of envelope that comes with a triangular flap that extends from the top of the envelope to the center of the bottom portion. LUXPaper offers a pack of 250 contour envelopes with a moistenable adhesive for easy gluing and sending.

Booklet Envelopes

Limited Papers | A9 Envelopes

A booklet envelope comes with a standard flap that is almost rectangular in shape, which extends to nearly both sides when closed. They either have peel and seal or moistenable glue underneath the flap for enclosing the envelope and keeping the card safe and sound. Limited Paper’s booklet-style envelopes come in three color options—white, red, and green.

Kraft Envelopes

Sodaxx 50 Packs A9 Kraft Brown Invitation Greeting Card Envelopes

A kraft envelope is an envelope that is made of paperboard. As such, it is more durable, isn’t exposed to bleaching, and is practically immune to discoloration. Kraft paper is generally made of 80% sulfate wood pulp. You can check out Sodaxx’s set of 50 A9 Kraft Brown envelopes to see how they look compared to other types of envelopes.

Lined Envelopes

Sodaxx 50 Packs A9 Kraft Brown Invitation Greeting Card Envelopes

A lined envelope is a kind of envelope that typically comes with a foil lining on the inside. The liner is used to increase aesthetics, but it doesn’t add much in terms of the overall weight of the envelope and card. JAM Paper has an excellent selection of A9 foil-lined envelopes with different exterior and inner-foil colors.


Baron Cooke has been writing and editing for 7 years. He grew up with an aptitude for geometry, statistics, and dimensions. He has a BA in construction management and also has studied civil infrastructure, engineering, and measurements. He is the head writer of measuringknowhow.com

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