Envelope sizes – a complete size guide

Woman Filling Envelope

Envelopes are a vital fixture in the office stationery cupboard. These everyday essentials help keep confidential documents private and transport important information from one place to the other.

But do you know your C5 from your DL+? We’ve created a handy all-in-one guide to envelopes and envelope sizes to help you find the right ones for your desk drawer.

Different envelope types

It might seem like an envelope is an envelope, but the documents you’re sending can determine which type you should purchase.

Here are the different envelope types typically available and what they’re used for, which will come in handy when deliberating what kind of envelope you need.


The largest envelope we supply at Solopress. It’s slightly bigger than the size of an A4 sheet of paper and perfect for sending documents without folding them. Usually, C4 envelopes are used when mailing certificates, important documents, brochures or magazines. Make sure your office is well stocked with this size.


The traditional-sized envelope. Bigger than the size of an A5 sheet of paper or for an easier reference, an A4 piece of paper folded in half. C5 envelopes are commonly used when sending greeting cards and wedding invitations. In the business world, they’re often used for sending longer letters. That’s because you can fit more pages into an envelope by folding A4 sheets in half.


The smallest envelope we supply at Solopress. They’re not seen as much in the post-box as other envelopes, but it’s still worth keeping a supply to hand. Normally, C6 size envelopes are used to send smaller items such as camera and phone memory cards or USB sticks.


You’ll probably receive DL-sized envelopes in the post all the time. They’re used when companies send official correspondence through the mail. They usually have a small, see-through window so the recipient can see their name and address. Pages are folded into thirds with DL envelopes and are suitable for one to three-page letters.


A popular envelope size in stock at Solopress. It’s specially made to send square-shaped documents (as the name suggests) such as greeting cards and wedding invitations. Not very common in post-boxes but handy to have around the office if you have special events coming up.

A guide to envelope sizes

When you know the size of the document you’re sending, you need the right envelope. Use this simple guide below to choose the correct envelope for whatever you’re sending.

Envelope size guide
Size Suitable paper size Width (mm) x Height (mm) Width (cm) x Height (cm) Width (inches) x Height (inches)
C4 A4 size 324 x 229 32.4 x 22.9 12.76 x 9.02
C5 A5 size (A4 folded in half) 229 x 162 22.9 x 16.2 9.02 x 6.38
C6 A6 size 162 x 114 16.2 x 11.4 6.38 x 4.49
DL A4 folded in thirds 220 x 110 22.0 x 11.0 8.67 x 4.33
DL+ A4 folded in thirds 229 x 114 22.9 x 11.4 9.02 x 4.49
Square Square document 220 x 220 22.0 x 22.0 8.67 x 8.67

Envelope FAQs

We receive queries all the time about envelope printing, designs, templates and purposes. Using our expertise, we always try to answer even the most technical questions. Discover a number of the questions we often receive an answer using our wisdom of the world of envelopes.

Do you have any pre-existing templates for envelope designs?

Yes, we do. There’s a useful selection of templates that can be found here. They’re free to download in a number of formats, including:

    • Photoshop
    • Illustrator
    • InDesign
    • PDF

Simply download, add your artwork and send to us.

Are high quantities of customised envelopes available from Solopress?

The answer is yes – we do sell envelopes in bulk. You can order between 250 and 200,000 envelopes from Solopress.

What type of paper is used to create envelopes?

Our envelopes are made from bond paper, a durable type that’s frequently used for stationary. Two paper weights are available at Solopress – 80gsm and 100gsm.

Where will my artwork feature on customised envelopes?

When you order customised envelopes through Solopress, you have the choice of either single-sided or double-sided printing.

Hopefully, you now have a better understanding of which envelope type is right for the documents you want to send out. But, are you looking for something a little more extravagant? Envelopes that say a little bit more about your company or event? At Solopress, we can help you express yourself. Customise your envelopes with your own artwork by downloading one of our envelope templates. Choose the size that’s right for you, add your own designs and we can bring your creations to life.