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Envelopes Buying Guide

Avoid wastage and unnecessarily high postage fees by using our envelope buying guide to ensure you always select the right envelopes for the job.

  • Choosing the right envelope

    Ideal for low-volume mailing Traditional lick-and-fold closure One year shelf life.

    Suitable for high-volume mailing Simply fold the tab against the adhesive Six month shelf life.

    Best for high-volume mailing Peel away the protective strip and fold the envelope shut Long shelf life, as the strip prevents the glue from drying out.

  • Envelope sizes

    'C' envelopes are slightly larger than their 'A' paper counterpart. C4 envelopes therefore hold an A4 sheet unfolded, or a thin brochure or catalogue.

    C5 envelopes hold an A4 sheet folded in half.

    DL envelopes hold an A4 sheet folded into thirds. They are a good size for cheques and standard compliments slips.

    C6 envelopes hold an A4 sheet folded into quarters.

    Postal prices increase with size, so use smaller envelopes whenever you can, keeping larger ones for documents that shouldn't be folded.

  • Envelope postage costs

    Royal Mail classes anything under 100g and 240mm x 165mm x 5mm as a Letter, while anything above this and under 750g and 353mm x 250mm x 25mm is a Large Letter. As you might expect, Large Letters are subject to higher fees, so you should use smaller envelopes wherever possible. You can find the envelopes and their sizes categorised according to the Royal Mail pricing system in the table below. Remember that you must also take into account the thickness when posting:

    Royal Mail category Envelope Size
    letter DL 220mm x 110mm
    C10 40mm x 28mm
    C9 57mm x 40mm
    C8 81mm x 57mm
    C7 114mm x 81mm
    C6 162mm x 114mm
    C5 229mm x 162mm
    Large Letter C4 324mm x 229mm

    You can purchase books of First and Second-Class stamps for Letters or Large Letters here at Viking - perfect if you want to avoid queuing up at the Post Office.

    The current Royal Mail pricing is based on the weight and size of an item being mailed, so you don't have to pay more than you need to.

  • Envelope paper types


    Just as with paper, envelopes are measured in GSM (grams per square metre). This weight is an indicator of thickness. Standard envelopes are around 80GSM, but if you need something that withstands higher levels of wear-and-tear and looks more professional, around 120GSM is recommended.
    Envelopes usually come in white or manilla (brown), but we also have a selection of coloured envelopes here at Viking. You will even find envelopes made from recycled materials.

    Specialist envelopes

    There are a number of specialist envelopes that will help you post more effectively.

    Board-back envelopes

    Board-back envelopes have a sturdy construction to help prevent the contents from being bent or folded. These are ideal if you are sending documents that will be displayed or presented, such as certificates.

    FSC Mix Credit

    FSC stands for the Forest Stewardship Council. Office Depot Envelopes are produced using a mix of material from sustainable FSC certified sources. FSC standards protects forests through preventing practices such as illegal logging, and civil rights violations.

  • Padded envelopes

    If you are sending something that could be damaged in the mailing process, you may prefer a padded envelope. Jiffy envelopes with bubble-wrap are extremely popular, but remember that these may exceed the Letter or Large Letter thickness and thus be deemed a parcel by Royal Mail.

  • Other specialist envelopes

    At Viking, you can also find air-mail envelopes, which are as light as possible to reduce postage costs; gusset envelopes, which can be expanded to provide you with more volume; resealable envelopes, the eco-friendly solution for internal communications; and more. Explore our range to find exactly what you need today.

  • Viking envelope product range

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