What is A3 flyer size? A3 leaflets, folds and pixels

Twice A4, and why that matters for folding

ISO 216 sizes halve with every step, so A3 folded once across its long side gives two A4 pages, a four page leaflet with a cover, a two page inside spread and a back. Fold again and you get A5 pages. Because the proportion never changes, the folded panel is a scaled copy of the open sheet, which makes A3 the natural size for a programme, a menu or a newsletter that needs four or eight pages without staples. The open sheet is what the printer runs, so the artwork file is 297 by 420 millimetres with the fold lines marked.

Planning panels and fold lines

Each fold needs room. Keep text at least 5 millimetres from a fold line, more on heavy stock where the crease bulges, and avoid running a face or a line of type across a fold. Decide the reading order before laying anything out: on a once folded A3 the reader sees the front, opens to the spread, then turns to the back. On a four panel roll fold, the inner panels must be a millimetre or two narrower than the outer ones so they tuck in without buckling, which is why printers supply their own fold templates.

Paper weight and scoring

A folded A3 leaflet on 130 to 150 gsm paper folds cleanly by machine. At 170 gsm and above the paper should be scored before folding, or the coating cracks along the crease and shows a white line through dark backgrounds. Gloss shows fingerprints and cracking most; silk is a common middle choice for event programmes. Flat A3 flyers for a noticeboard are better on 170 gsm or heavier so they hang flat, and in practice they behave as small posters rather than flyers.

Common mistakes with A3 leaflets

The first is designing the four pages as separate A4 files and leaving the printer to impose them, which puts the back cover and the front cover in the wrong places on the sheet. The second is placing a photo across the centre fold so a face is creased. The third is forgetting that a folded A3 leaflet will not go through many letterbox slots without a second fold. The fourth is mixing up the A3 page with the A3 poster: the same sheet, but a poster is read at a distance and a leaflet in the hand.

A3 and the flyer editor

The flyer editor has no A3 canvas; its print sizes are A4 portrait and A4 landscape. For a folded leaflet the practical route is to design each panel as its own A4 page in one multi page flyer, export the PDF, and have the print shop impose the pages onto A3 with the folds. For a flat A3 sheet, an A4 portrait design scales up to A3 with no cropping because the proportions match, and the 2480 by 3508 export lands at about 212 DPI on A3, enough for a noticeboard. The flyer size resizer outputs the exact A3 pixel size, and the blank 3508 by 4961 PNG above is A3 at 300 DPI.

Questions people ask