Envelopes – A Comprehensive Guide
Having recently produced some overprinted C6 envelopes for local client The Dragon Café, we thought we’d put together a useful ready-reference guide to envelopes. We’ve included information on available shapes, sizes, formats, sealing mechanisms, styles, materials and more. There is also a note about overprinting options for those who need their own, unique envelope, perhaps showing their branding or allowing the envelope to serve a specific purpose, for example for collecting donations (see The Dragon Café’s fundraising example, shown below right). Take a look below and bookmark this page if you think it might be useful for future reference — we hope so!
Envelope Sizes
The three most popular size conventions for envelopes are ‘ISO C’ (‘C’ for short), ‘DL’ and square envelopes and we’ll explain how they work in a moment. There is also a fourth range, being the ‘ISO D’ sizes (used to suit ‘ISO B’ paper sizes) but they’re rarely used in the UK, so we’ll not go into detail about those here.
‘ISO C’ Sized Envelopes
You will be almost certainly be familiar with A4, A3 and A2 sized papers. These come from the ‘ISO A’ series of paper sizes. ‘ISO C’ sizes are a complementary range of sizes that are widely used with envelopes to house ‘A’ sized papers. So, for example, an unfolded A4 letter would fit neatly inside a C4 envelope (with a little breathing space). Meanwhile, if you fold an A4 letter in half (so it’s now A5), it would fit perfectly into a C5 envelope. If folded again into A6, it would fit nicely in a C6 envelope, and so on. Here are the most popular ISO C envelope sizes:
- C3 envelopes are 458mm x 324mm
- C4 envelopes are 324mm x 229mm
- C5 envelopes are 229mm x 162mm
- C6 envelopes are 162mm x 114mm
Now we’ll come onto what happens if you fold that A4 letter into three rather than two …
ISO ‘DL’ and ‘DLE’ Envelope Sizes
The envelope size 220mm x 110mm is commonly referred to by stationers and printers as ‘DL’ (short for DIN Lang, meaning DIN ‘Long’). It’s a perfect size to suit A4 letters folded into three. However, strictly speaking, true ‘DL’ is actually exactly one-third A4 i.e. 210mm x 99mm but true DL is seldom, if ever, used in the UK. So when we refer to ‘DL envelopes’ when speaking with stationers or printers in the UK, it’s understood that we’re really talking about ‘DLE’ size (the true name for 220mm x 110mm). It’s one of life’s little quirks!
Square Envelopes
The UK enjoys a huge range of different square envelope sizes. They are too numerous to list in full but the most popular among them include:
- 80mm square
- 100mm square
- 105mm square
- 110mm square
- 116mm square
- 120mm square
- 126mm square
- 130mm square
- 140mm square
- 155mm square
- 160mm square
- 164mm square
- 220mm square
- 240mm square
- 254mm square
- 317mm square
Envelope Opening Formats
When ordering envelopes from your printer or stationer, they may ask you whether you require ‘wallet’ or ‘pocket’ format. But what does that mean? ‘Wallet’ format simply means Read more
The Dragon Café is the UK’s first mental health café and creative space. It is the flagship project of Mental Fight Club, which explores all aspects of mental health through the use of creativity and public events. It is open every Monday, from midday to 8.30pm, and provides free, open-to-all, creative and well-being activities helped along with a simple, healthy and affordable food menu.