What Are the Dimensions of a C6 Envelope?
C6 envelope measurements, what fits inside, and whether it counts as a standard letter.
C6 dimensions
Quick answer
A C6 envelope measures 114mm x 162mm. It fits A6 cards and paper, or A4 paper folded into quarters. C6 is the standard envelope for greeting cards and fits within Royal Mail's standard letter dimensions, so it only needs a standard stamp (75p second class or £1.10 first class) as long as it stays under 5mm thick and 100g.
What fits inside
C6 is designed for A6 paper (105mm x 148mm), which is a quarter of an A4 sheet. Most standard greeting cards, RSVP cards, and small invitations fit this size. If you fold an A4 sheet twice (into quarters), it also fits a C6 envelope.
Postage costs
A C6 envelope fits within the Royal Mail standard letter category (max 240mm x 165mm x 5mm, 100g). This means you can use a standard stamp rather than the more expensive large letter rate. Keep the envelope thin and light to stay within standard letter limits.
Compare envelope sizes: C5 dimensions or envelopes for A5 cards.
Common uses
C6 is the most popular envelope for greeting cards, thank-you notes, wedding RSVPs, party invitations, and personal correspondence. It is also used for small documents, vouchers, and gift cards.
C6 envelopes for every occasion
White, ivory, and coloured C6 envelopes for greetings, invitations, and business correspondence.
Browse C6 envelopesFrequently asked questions
114mm x 162mm (approximately 4.5 x 6.4 inches).
A6 paper or cards (105x148mm), or A4 folded into quarters.
Yes, it fits within Royal Mail standard letter dimensions, so a standard stamp is sufficient.
A standard stamp: 75p second class or £1.10 first class, as long as it is under 5mm thick and 100g.
C6 (114x162mm) fits A6 cards. C5 (229x162mm) is larger and fits A5 paper or A4 folded in half.
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