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Deciphering the Print Code: Envelope, Paper and Post Size Guide

Can’t tell your DLs from your C4s? Not to worry, we’ve put together this envelop, paper and post guide featuring the most popular and commonly used print sizes. BUT before you pick your paper size – first consider the following:

  • What sized envelope will your material fit inside?
  • Can you fold the material you’re sending?
  • Does it exceed the size of a letter as defined by Australia Post?
  • Which envelope will be most cost and time efficient to use?


Format Dimension   Paper Size 
 DL110mm x 220mm  A5 folded once, A4 folded twice
 DLX120mm x 235mm  Fits more documents than a DL size
 C3458mm x 324mm  A3 Unfolded
 C4324mm x 229mm  A4 unfolded, A3 folded once
 B4353mm x 250mm  A4 unfolded, best for thicker paper
 C5229mm x 162mm  A5 or A4 folded once
 C6114mm x 162mm  A6, A5 folded once, or A4 folded twice
 11B90mm x 145mm  Typically used as Reply-Paid envelopes


Let’s Talk Envelopes: There’s More to Consider than Just Size

In addition to the various sizes available (check out our guide on Envelope, Paper and Post Size Guide if you haven’t already), envelopes come with differing features relating to their flap style, seal style and envelope face.

There are two flap styles; wallet or pocket.

  1. Wallet (also known as banker) – an envelope that opens on the long edge.
  2. Pocket – an envelope that opens on the short edge.

There are three closure styles;

  1. Lick and stick (or gummed) – this style requires moisture to seal.
  2. Peel ‘n’ seal – peel back the strip protecting the adhesive and seal.
  3. Press seal (or self-seal) – press the strips of latex on each flap together to seal.

The two face types are;

  1. Plain face – an envelope without windows.
  2. Window face – includes a window on the front, for pre-printed addresses.

If you are planning to post material, the following criteria must be met for your item to be considered a “letter”:

  • Weigh no more than 500g
  • Item must be flexible
  • Be rectangular in shape
  • The largest “letter” size is a B4 envelope
  • An item any thicker than 20mm will be considered a package

Printed DLX Envelopes. Customise your envelopes with your brand or campaign logo or key messages.

Make an impact with your design

When mailing items to customers, suppliers and other stakeholders, do not underestimate the importance of the appearance of your direct mail. A professional looking envelope will call attention to your item and is a representation of your business. Printed envelopes provide consistency in branding and help the customer identify the material immediately.

How print became the new “new media”

Use this guide so you will know exactly what envelope size and paper size match and you will be sending material more efficiently, without untidy looking folds ruining the appearance of your material.


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