Card & Envelope Size Calculator
Start from the card you want to make and get the envelope that fits it, the flat blank to cut, the score line, and the nearest off-the-shelf envelope size.
Envelope & card blank
Sizing a card and its envelope
A handmade card only feels finished when it slips into an envelope cleanly. Work from the finished card size: the envelope needs a little clearance on each side, and the flat blank you cut is double the card in the fold direction, scored once so the fold is crisp rather than cracked.
If you would rather buy envelopes than make them, the nearest-standard match tells you which A-line size to reach for, so you can design the card around a pack you already have.
Frequently Asked Questions
How much bigger than the card should the envelope be?
The envelope interior should clear the card by a few millimetres on each dimension so it slides in without forcing. A total of about 6 mm added to width and height suits a normal single-layer card; go up to 10 mm for a thick or layered card, and as tight as 3 mm for a slim flat one.
What is the flat card blank?
It is the piece of cardstock you cut before folding. For a side-folded card the blank is twice the finished width, scored down the middle; for a top-folded card it is twice the finished height. The calculator gives both the blank size and the score position.
What are A2, A6, and A7 envelopes?
They are the common US A-line invitation envelopes. A2 suits a card around 108×140 mm, A6 around 114×159 mm, and A7 around 127×178 mm. The tool matches your card to the smallest standard envelope that will hold it, so you can buy a ready-made pack.
Does it work in inches?
Yes — switch the units to inches and enter your card size that way. Everything, including the envelope and blank, is reported back in the unit you chose.
Guidance only. Standard envelope dimensions vary slightly by maker; check one against your card before cutting a whole batch.