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cm Envelope Size 9: Dimensions & Details

By Gabriel Aug 06, 2026
an overview of envelope sizes and how to use them
an overview of envelope sizes and how to use them

Ever found yourself puzzling over international standardized envelope sizes? The #9 envelope size, often mentioned in cm, can be quite confusing. Don't worry, you're in the right place. Let's demystify this size and help you navigate the world of envelope sizes.

an overview of envelope sizes and how to use them
an overview of envelope sizes and how to use them

In case you're wondering, the #9 envelope size is part of the international standard envelope size system. This system uses a numeric code to identify different envelope sizes, which is particularly useful when communicating globally.

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Understanding the #9 Envelope Size

The #9 envelope size is one of the C sizes, which fall between B and C6 in the international envelope size standard. This means it's larger than a typical letter-sized envelope but smaller than a C6 envelope.

an envelope size guide for business
an envelope size guide for business

Expressed in centimeters, the #9 envelope dimensions are typically 229mm by 110mm (length by width). This size is often used for shipping documents, application forms, or other items that are larger than a standard letter but not oversized.

When to Use a #9 Envelope

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UMI Brown Envelopes Short & Long 25pcs,50pcs For Office & School Supplies

So, when should you reach for a #9 envelope? If you're sending important documents that don't quite fit into a standard #10 envelope but are too large for a #6, a #9 is your best bet. It's also a good size for large greeting cards or thin documents that need a bit more space.

On the other hand, if you're sending a thick document or a package, you might want to consider a larger envelope size, like a #11 or even a flat rate envelope.

Finding #9 Envelopes

an origami envelope with the measurements for it to be cut out and put in
an origami envelope with the measurements for it to be cut out and put in

Now that you know when to use a #9 envelope, you're probably wondering where to find them. Many office supply stores carry these envelopes, and you can also order them online. When buying, make sure to check the product description to ensure you're getting the correct size.

Some online retailers also offer custom printing services, allowing you to add your company logo or recipient's address directly to the envelope for added convenience.

Comparing #9 Envelopes with Other Sizes

an envelope is shown in the shape of a square, with two sides cut out
an envelope is shown in the shape of a square, with two sides cut out

To better understand the #9 envelope size, it's helpful to compare it with other common envelope sizes. Here's a quick rundown:

- A #6 envelope measures 110mm by 60mm. - A #9 envelope measures 229mm by 110mm. - A #10 envelope measures 245mm by 105mm. - A #11 envelope measures 279mm by 105mm.

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Printable Envelope Template | A7 Envelope Template | Envelope for 5 x 7" card | PDF & SVG
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#9 vs #10 Envelope: Which to Choose?

When deciding between a #9 and a #10 envelope, consider the size and thickness of your item. If it's slightly wider than a standard letter but not overly thick, a #9 will suffice. If your item is wider and/or thicker, opt for a #10 envelope.

Always remember that the extra space could be necessary to ensure your item arrives safely and doesn't get damaged during transit.

Why #9 Envelopes are Convenient

#9 envelopes strike a balance between being too small and too large. They're not so big that you waste space and money on postage, but they're not so small that you have to cram your items in. This makes them a handy size to have on hand for a variety of shipping needs.

Moreover, their standard dimensions mean they're accepted by most postal services worldwide, making them an excellent choice for international shipping.

In the end, understanding and using the right envelope size can save you time, money, and hassle. Whether you're sending important documents or greeting cards, a #9 envelope is a versatile tool in your shipping arsenal. So next time you're at the post office, don't hesitate to reach for a #9 envelope when you need it.