UK Paper Sizes Explained: A6 to A0 in mm, cm and Pixels

The UK uses the ISO A-series: each size is exactly half the one above it, folded across the long edge. A4 (210×297mm) is standard office paper; A5 is half that and the most common flyer size; A1 and A0 are poster and plan sizes.

The full table

Size	mm	inches	Pixels @300dpi	Common use
A0	841×1189	33.1×46.8	9933×14043	Plans, large posters
A1	594×841	23.4×33.1	7016×9933	Conference posters
A2	420×594	16.5×23.4	4961×7016	Shop posters
A3	297×420	11.7×16.5	3508×4961	Small posters, menus
A4	210×297	8.3×11.7	2480×3508	Documents, letterheads
A5	148×210	5.8×8.3	1748×2480	Flyers
A6	105×148	4.1×5.8	1240×1748	Postcards
DL	99×210	3.9×8.3	1169×2480	Tri-fold panel, envelopes

What is DL?

DL (99×210mm) is one-third of A4 — the panel size of a folded tri-fold leaflet, and the size that fits a standard DL envelope. See leaflet folds explained.

Which size should my flyer be?

A5 is the default: big enough to read, cheap to print (500 from £65), fits through letterboxes flat. A6 halves your paper cost for short punchy messages; A4 suits information-dense pieces like price lists.

Remember to add bleed

All the sizes above are trimmed sizes. Supply files 6mm larger each way (3mm bleed per side) — bleed explained here.

FAQ

What's a business card size in the UK? 85×55mm — not part of the A-series. Why do US sizes differ? The US uses Letter (216×279mm), slightly wider and shorter than A4. Can you print larger than A0? Yes — PVC banners are made to custom sizes; banner prices here.