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Size charts

Size chartsUpdated

Envelope sizes

Envelopes come in a handful of standard sizes, each made for a sheet of paper or a card. Here are the common ones, from the DL for a folded letter to the C4 for an A4 sheet kept flat, plus the two everyday US sizes.

Size chart by what goes in

SizeWidth × heightDieline
DL
An A4 letter folded in three
220 × 110 mm
8.66 × 4.33 in
Glued →
Tuck flap →
C6
An A6 card, or A4 folded in four
162 × 114 mm
6.38 × 4.49 in
Glued →
Tuck flap →
C5
An A5 sheet, or A4 folded once
229 × 162 mm
9.02 × 6.38 in
Glued →
Tuck flap →
C4
An A4 sheet, flat
324 × 229 mm
12.76 × 9.02 in
Glued →
Tuck flap →
#10
A US letter folded in three
241.3 × 104.8 mm
9.50 × 4.13 in
Glued →
Tuck flap →
A7
A 5 × 7 in card or invitation
184.2 × 133.4 mm
7.25 × 5.25 in
Glued →
Tuck flap →

DL and the C sizes are the international ones (ISO 269); #10 and A7 are North American. The sizes are the finished envelope. What goes in should be a few millimetres smaller on each side.

How to measure

  • Width: along the opening, side to side, the long edge.
  • Height: from the bottom fold to the top fold, where the seal flap turns over.
  • Start from what goes in: add about 5 mm to its width and height, or pick the standard size made for it.

Straight or pointed flap?

A straight flap is the everyday one: it is glued shut, by you or by a strip of adhesive (the envelope). A pointed flap tucks its tip into a small slit in the back, so it closes without glue and opens again: nice for invitations and gift cards (the tuck flap envelope).

Sending something bigger? See the mailer bag sizes.

Related guides

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