What is the standard UK envelope for wedding invitations?

C5 (229 x 162 mm) is the most popular for UK wedding invitations, fitting an A5 card. DL (220 x 110 mm) is standard for letters. Square envelopes (155 x 155 mm) are popular for informal invitations but cost more to post.

Where should I position the address on an envelope?

Royal Mail recommends the delivery address sits in the centre area of the envelope, left-aligned (do not centre or stagger the individual lines), with a clear margin around it and kept clear of the stamp area in the top-right. For calligraphy, a slightly-left-of-centre, vertically-centred block looks balanced. Source: Royal Mail "A guide for letter envelope design and clear addressing" (Nov 2019).

How many address lines should I allow?

A typical UK address has 5-6 lines: name, house number and street, locality (optional), town, county (optional), postcode. Always include the postcode on its own line or clearly separated.

Should I include a return address?

Yes — Royal Mail recommends a return address on the back flap or top-left corner of the front. For calligraphy envelopes, the back flap is traditional for formal correspondence.

What x-height works best for envelopes?

For DL and C6 envelopes, 3-4 mm x-height works well. For C5 and C4, you can go to 4-5 mm. The text should not look cramped or overwhelm the envelope. Always do a test layout before your final batch.

ArtCalcs

Envelope Calculator — Calligraphy Envelope Layout

Work out text positioning and layout for addressing calligraphy envelopes.

Envelope Size

X-Height

The minim (small-letter) body height of your chosen hand, in mm

Address Lines

Lines in the delivery address (UK addresses are typically 5–6: name, street, town, county, postcode)

Return Address

Line SpacingBaseline-to-baseline spacing as a multiple of x-height. 2.5–3× is the broad-edge convention to clear full ascenders + descenders + an interline gap (Johnston / Lettering-Daily guideline practice).

How We Calculate This

How Envelope Layout Works

Line spacing = x-height × factor (2.5× tight to 3× open)

Baseline-to-baseline spacing of about 2.5–3× the x-height is the standard broad-edge convention: it leaves room for full ascenders, full descenders and an interline gap without crowding (Johnston pen-width pedagogy / Lettering-Daily guideline practice). Pick 2.5× for compact addressing or 3× for an airier block. The address block then sits in the lower-centre area, and the calculator gives precise X/Y positions for the address start, return address and stamp zone based on the envelope size you choose.

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.