Envelope Help Guide

Choosing the right envelope

Given the variety of colour and size of envelopes available it can be confusing, so here are a few tips to help you find the right envelope:

1) Don't leave it to the last minute
We offer a huge range of envelopes. Some are stock items, some are special order. Please check the lead times and allow enough time for delivery to avoid disappointment.

2) Choose your envelope size first
We deal with so many enquiries from people who have designed a card or insert before choosing an envelope, and then can’t find the envelope to fit.

3) Check the exact size
Sizes quoted are for the envelope, not the insert. Always check the exact size of the envelope, which should be listed on the website. Some envelopes vary by small amounts from standard sizes. We recommend allowing a 5mm clearance around your insert.

4) What style of flap do you want?
There is a choice of two styles. Wallet style is a straight flap, usually on the long edge. Diamond is a pointed flap, a popular choice for invitations. There is also a choice of two seals - gummed or peel-and-seal. Gummed requires wetting before sealing. Peel-and-seal has a strip you peel off and stick the flap down.

5) Paper weight and style
As a guide, paper weights for envelopes generally range between 80 and 120gsm (grammes per sq. metre). 100gsm is a good standard weight for most uses. Wove is a smooth finish paper. Laid paper has a slight texture or grain.

Standard envelope sizing system:

  • C4 envelopes (size 324 x 229mm) fit A4 paper flat
  • C5 envelopes (size 229 x 162mm) fit A5 paper flat OR A4 folded once in half
  • C6 envelopes (size 162 x 114mm) fit A6 paper flat OR A4 folded in half and half again OR A5 folded once in half
  • DL envelopes (size 220 x 110mm) fit A4 paper folded twice across. This is the standard letter size.

Please note: The sizes of envelopes and paper sold on this website do not necessarily correspond exactly to standard measurements - each envelope and/or paper may differ slightly to the standard size by a small tolerance - always check the quoted size on the product page before ordering.

ISO Standard sizes for paper and envelopes

These are the generally accepted standard sizes across most of the world. They work on the principal of each size being half the size above, if folded in the middle (e.g. A4 is made up of 2 sheets of A5, side by side).

A sizes (paper)
This is the standard paper measurement system, most commonly used. It starts with A0, which is actually 1 square metre.

B sizes (paper & envelopes)
This is an alternative system of paper sizes, to meet requirements that the 'A' series does not meet. Note that there is also a 'B' series of envelopes, and that this is slightly larger than the 'B' paper.

C sizes (envelopes)
This is a system of providing standard envelope measurements. They are equivalent to the 'A' sizes of paper (e.g. C4 envelopes are designed to take an A4 sheet of paper flat).

ISO Standard Paper & Envelope Sizes - all sizes are in mm

A Sizes (paper)
B Sizes (paper)
C Sizes (envelopes)
A0 841 x 1189 B0 1000 x 1414 C0 917 x 1297
A1 594 x 841 B1 707 x 1000 C1 648 x 917
A2 420 x 594 B2 500 x 707 C2 548 x 648
A3 297 x 420 B3 353 x 500 C3 324 x 548
A4 210 x 297 B4 250 x 353 C4 229 x 324
A5 148 x 210 B5 176 x 250 C5 162 x 229
A6 105 x 148 B6 125 x 176 C6 114 x 162
A7 74 x 105 B7 88 x 125 C7 81 x 114
A8 52 x 74 B8 62 x 88 C8 57 x 81
A9 37 x 52 B9 44 x 62 C9 40 x 57
A10 26 x 37 B10 31 x 44 C10 28 x 40