Choosing the Right C4 Envelopes

C4 envelopes are sometimes known as A4 envelopes because they’re designed and sized to fit an A4 sheet without folding. C4 envelopes are sized at 324mm x 229mm and come made in a variety of paper weights from the lightweight 80gsm up to heavyweight 130gsm.

Envelope Weight

c4 envelopes

If you’re looking for the cheapest mailing envelope then a plain (non window), 80gsm manilla pocket envelope with a gummed closure is the one to go for as these can be bought for around £18 for a box of 500. At the other end of the scale, if you’re looking for a quality, professional envelope, designed to impress then a 120gsm, bright white envelope with a peel and seal closure is the one to choose from manufacturers such as Basildon Bond, Plus Fabric or Croxley Script.

Envelope Closure

There are three types of envelope closure, the cheapest being gummed which has a dry gummed strip on the closure which needs to be moistened to activate the adhesive, sometimes known as a ‘lick & stick’ closure. This is ok if you have a limited number of envelopes to post but if you mail in volumes then you should consider press seal or peel and seal envelopes.

Press seal closures have adhesive strips on the closure flap which is activated by pressure when closing the closure flap. These are great if you’re mailing in volume but be aware that over time the adhesive dries out, reducing the effectiveness of the adhesive and consequently the security of the envelope closure.

If you use C4 envelopes infrequently and store them for periods of more than a month then it’s probably best to go with a peel and seal enclosure. This has the adhesive strips protected from drying out by a plastic strip which is peeled off the adhesive at the time of use ensuring a secure seal to the envelope.

Envelope Styles

Besides the standard C4 envelopes, they are also available as gusseted envelopes and board backed envelopes. Gusseted envelopes are robust, heavyweight envelopes with gusseted sides which can expand to accommodate thick A4 sized documents such as catalogues or reports. C4 Board backed envelopes have a semi rigid board to the rear of the envelope which prevents the envelope being creased or folded in transit, ensuring the documents being posted arrive undamaged and without creases. These are ideal for mailing certificates or photographs.


Carl Barton is a director of Office Allsorts who has worked in the office products industry for 15 years.

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