Custom C5 Envelopes

Paper Weights and Colours

Standard office envelopes are made from white wove paper around 90 to 100 gsm, which is light, inexpensive and easy to print. For brochures and heavier contents, a 110 to 120 gsm paper resists tearing and feels more substantial in the hand. Premium envelopes in textured, laid or smooth uncoated papers suit law firms, hotels and luxury brands.

Coloured envelopes get post noticed on a doormat. Kraft envelopes have a natural brown look and are tough enough for heavier items, while pastel and bright colours suit invitations and promotional mailings. Opaque or security-tinted interiors stop the contents being read through the paper, which is important for financial and personal documents.

If you are posting something slightly bulky, such as a booklet with a card cover, a gusseted C5 expands to take the extra thickness without splitting at the seams. The gsm figures for envelope paper are set out in our paper weights explained guide.

Windows, Seals and Opening Options

A window envelope shows the address printed on the letter inside, which saves time printing labels and reduces the chance of a mismatch between envelope and contents. Windows are usually placed on the left for standard letter layouts, but they can be positioned to suit your documents. Plain envelopes without a window look more personal and suit invitations and marketing.

Self-seal envelopes have a strip of adhesive covered by a peel-off strip, which is quick and clean for hand-filling. Gummed envelopes need moistening and are usually the cheaper option for machine-filled mailings. Wallet envelopes open along the long side and are better for inserting brochures, while pocket envelopes open on the short side and suit documents that are slid in. The same seal and window options apply to our printed envelopes in other sizes.

Designing the Envelope Front and Back

Keep the front simple. The address area must stay clear so postal sorting machines can read it, so place your logo in the top left corner and leave the right side for the stamp or franking mark. A return address on the back flap is useful if the post cannot be delivered.

Marketing envelopes can carry a short message on the front, such as an offer or an invitation to open, but keep it away from the address window and franking area. Full colour printing across the whole envelope is possible but costs more, so many businesses choose one or two brand colours for the logo and return address. Printing inside the flap with a pattern or brand colour is a subtle detail that shows when the envelope is opened.

If you are unsure how much to print, start with the logo and return address only. That version works for almost every mailing you send, from invoices to invitations, so it never goes out of date. You can always add a second, more promotional design later for a specific campaign, and keep the plain version as your everyday stock. Matching your envelope colours to your letterheads and compliment slips also makes even routine post feel joined up.

Planning Postage and Quantities

A C5 envelope usually posts as a large letter, provided it is not too thick or heavy. If you plan to include a booklet or several sheets, weigh a filled sample before you print a large batch, because a few extra grams can move it into a higher postage band.

It is often more economical to order envelopes for the year ahead in one run, especially if the design does not change. Storing them flat and dry keeps the adhesive in good condition. If you send different types of mailing, such as statements and marketing, ordering two versions in one job keeps branding consistent.

Think about how the envelopes will be filled. If you use a mailing house or an inserting machine, check its requirements before ordering, since many machines need a specific flap shape, gummed seal and paper weight. For hand-filled post, self-seal wallet envelopes are the friendliest choice and speed up a busy afternoon of mailing. Greetings and reply cards for the same mailing go in C6 envelopes for A6 cards.

Fold a Test Letter and Post It to Yourself

The cheapest check on a C5 envelope is a dummy mailing. Fold your real A4 letter once, slide it into any C5 envelope, mark where the address and logo fall, and post it to your own office. That tells you if a window will show the address and how the envelope looks after a day in the post. Then settle the window position, the seal type and the paper weight, and tell us the quantity for each version if you need window and plain together. Artwork is the logo for the top left, the return address for the flap and any colour on the back, sent as vector files. A custom quote comes by email within one working day, with envelopes from £0.25 depending on paper and print, and minimums set per job. The free proof shows front and back with the window outline, printing takes 4 to 7 working days after you approve it and UK mainland delivery is free and tracked. Stationery to go inside is printed on our letterheads printed to match.