Envelope Size Calculator

Find the envelope that fits a finished card, with the clearance it needs, and check the thickness against the postage bands.

Card width mm

The shorter side of the finished card.

Card height mm

The longer side of the finished card.

Card thickness mm

One gsm is about one thousandth of a millimetre for uncoated card, so 300 gsm is about 0.3 millimetres.

Clearance per side mm

Two to three millimetres per side suits most cards. A square card, or one with depth, wants more.

Inserts and embellishments mm

Anything inside the envelope besides the card: a ribbon, a badge, a second card, tissue.

Envelope weight

A heavier card needs a heavier envelope or it creases in the post.

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Free calculator by Handcraft worked examples and methodology No account, nothing stored.