A postcard is generally a rectangular piece of card that is mailed without an envelope. Although the there are a variety of different size and shapes of postcards; The ISO 216 standard has defined postcard size to be 105mm × 148mm, which is also the same size as A6 and hence a quarter the size of an A4.
Usually postcard size stock will be used for postcards, flyers, leaflets, invitations and cards.
- Postcard size is equivalent to A6.
- Postcard size is a quarter the size of A4, and half the size of A5.
- Postcard size is one-eighth the size of A3, and one-sixteenth the size of A2.
- Thirty-two postcard size paper will make up an A 1 sheet, while sixty-four to make up an A0.