A4
210 X 297 MM | 21 X 29.7 CM | 8.3 X 11.7 INCHES
This is the size that most people in the UK and worldwide put in their home or office printer. Requires a C4 envelope when posting flat as a Large Letter. Folded in half, it will fit a C5 envelope, and into thirds, a DL envelope.
A3
297 X 420 MM | 29.7 X 42 CM | 11.7 X 16.5 INCHES
Often used for smaller posters. Twice the size of A4.
A5
148 X 210 MM | 14.8 X 21 CM | 5.8 X 8.3 INCHES
A5 sized stationery is the size of a standard sheet of A4 paper that’s been folded in half along its longest edge.
- The size of larger invitation cards, greetings cards and lots of notebooks
- Requires a International C5 Sized envelope or postal box
- The largest size flat card for posting as a Standard UK Letter
- When using postal/invitation boxes (for example, to protect fancy ribbon-tied wedding invitation bundles) or when bundling more than 6-8 flat cards in one envelope, this size will class as a UK Large Letter
A6
105 X 148 MM | 10.5 X 14.8 CM | 4.1 X 5.8 INCHES
A6 sized stationery is the size of a standard sheet of A4 paper that has been folded twice (into quarters).
- “Postcard” size
- Used for larger RSVPs, note cards and smaller invitations
- “More details” and enclosure cards in conjunction with 5×7 invitations
- Correspondence cards and Thank You cards
- Requires an International C6 envelope for postage
148mm Square
148 X 148 MM | 14.8 X 14.8 CM | 5.8 X 5.8 INCHES
Square sized card—both the width and height are equivalent to the shortest side of an A5 sheet of paper or the longest side of an A6 sheet of paper.
- Requires a 155 mm square envelope
- Posts in the UK as a Standard Letter
5x7"
127 X 178 MM | 12.7 X 17.8 CM | 5 X 7 INCHES
A nice size for invitations measuring in at somewhere between standard A5 and A6 sizes. The US standard for wedding invitations.
- Requires a US “A6 – Thompson’s Standard” envelope*
- Posts as a Standard UK Letter (under 100g in weight)
- Also a good size for correspondence cards
* Be aware that the US “A6” envelope does not correspond to our A6 ISO Paper size. The dimensions are different!
105mm Square
105 X 105 MM | 10.5 X 10.5 CM | 4.1 X 4.1 INCHES
Square sized card—both the width and height are equivalent to the shortest side of an A6 sheet of paper or the longest side of an A7 sheet of paper.
- Requires a 110 mm + square envelope
Standard UK Business Card
55 X 84 MM | 5.5 X 8.4 CM | 2.2 X 3.3 INCHES
Often used interchangeably with A8 for escort cards or place settings
A7
74 X 105 MM | 7.4 X 10.5 CM | 2.9 X 4.1 INCHES
Half the size of A6 paper, or a standard A4 sheet folded 3 times.
A8
52 X 74 MM | 5.2 X 7.4 CM | 2 X 2.9 INCHES
Half the size of A7 paper. A little bit smaller than a standard business card.