A series paper sizes: halve it, keep the shape, and pick the right one

A series paper sizes follow one simple rule: start with a sheet of one square metre (A0, 841 × 1189 mm) and cut it in half again and again. Half of A0 is A1, half of A1 is A2, and so on down to A7 at 74 × 105 mm. The everyday ones worth knowing by heart are A4 at 210 × 297 mm, A5 at 148 × 210 mm and A3 at 297 × 420 mm. Below: the full list, the halving trick, bleed sizes and which size to reach for.

The halving trick that makes it all click #

Every sheet in the series has the same proportions, with the long side about 1.414 times the short side (that is the square root of 2). The clever bit is what happens when you fold one in half across its long edge: you get the next size down, and it is exactly the same shape. So:

• fold an A4 letter in half and you are holding A5;
• lay two A4 sheets side by side and you have A3;
• four A3 sheets make an A1 poster, and sixteen A4 sheets tile an A0.

This is set out in the international standard ISO 216. The practical upshot for anyone ordering print is that a layout made for one A size scales cleanly to another, with nothing stretched or chopped off. Blow an A4 poster up to A1 and it simply gets bigger, as long as your photos have enough pixels to cope (see image resolution for print).

A series paper sizes, smallest to largest #

Short side first, as is the convention. The last column shows how many of each sheet fit in one A0.

Sheet	Width by height (mm)	Roughly in inches	Per A0
A7	74 by 105	2.9 by 4.1	128
A6	105 by 148	4.1 by 5.8	64
A5	148 by 210	5.8 by 8.3	32
A4	210 by 297	8.3 by 11.7	16
A3	297 by 420	11.7 by 16.5	8
A2	420 by 594	16.5 by 23.4	4
A1	594 by 841	23.4 by 33.1	2
A0	841 by 1189	33.1 by 46.8	1

Need centimetres? Move the decimal point one place: A4 is 21 by 29.7 cm. Notice too that each sheet’s long side is the next size down’s short side doubled (near enough), which is the halving rule showing through.

Upright or on its side

Writing “A3, 297 × 420 mm” does not fix the orientation. Portrait (tall) is normal for posters, flyers and most signs; landscape (wide) suits panoramic photos, arrows and menu boards. On our product pages you pick the size, and your artwork decides which way up it goes. A few items list landscape separately, such as Foamex strut cards in A4 and A3 landscape.

Neighbours of the A series #

A handful of other sizes turn up alongside the A series paper sizes and are worth knowing:

• DL, 99 × 210 mm: a third of an A4 sheet. It drops into a DL envelope and a standard leaflet rack, so it is a regular for price lists and door drops.
• Square flyers, 148 × 148 mm and 210 × 210 mm: they share one side with A5 and A4. Nice for invites and menus, but they will not go in a DL envelope.
• C envelopes: built to hold A sheets. Our printed envelopes come as DL (220 × 110 mm, for A4 folded in three), C5 (229 × 162 mm, A5 flat or A4 folded once) and C4 (324 × 229 mm, A4 flat).

What we make in each size #

A quick map from sheet to product, so you can see what is available before you design:

• A7 and A6: flyers, which run all the way from A7 to A3.
• A5: flyers, posters, NCR invoice books and NCR sets.
• A4: flyers, posters, A4 Correx boards, signs, letterheads and NCR pads.
• A3: flyers, posters, signs and boards, and Foamex strut cards.
• A2: posters, A-frame pavement signs, menu boards, and Correx, Foamex and Dibond signs.
• A1: posters, A-frame pavement signs, and A1 Correx boards plus Foamex and Dibond signs.
• A0: posters, Correx boards, presentation boards and site safety boards.

A delivery note while we are here: boards up to A0 go at the normal rate (£7.95 to the UK mainland, free on orders of £100 or more after discounts). Boards bigger than A0 add £15 for oversize handling.

Setting up A series paper sizes with bleed #

If colour or a photo runs right to the edge, give the file 3 mm of bleed on every side, which makes the page 6 mm bigger each way. Here are the page sizes to type in:

• A7 finishes at 74 × 105 mm, so set the page to 80 × 111 mm.
• A6: page 111 × 154 mm.
• A5: page 154 × 216 mm.
• A4: page 216 × 303 mm.
• A3: page 303 × 426 mm.
• A2: page 426 × 600 mm.
• A1: page 600 × 847 mm.
• A0: page 847 × 1195 mm.

On signs and boards, keep text 10 mm or more inside the finished edge. Print bleed explains why that margin saves you from white slivers and clipped words, and the artwork guidelines list the file types we take. Every uploaded file is checked by a person for free before it goes to print.

Picking a size by where it will be read #

The best question is not “what size looks nice” but “how far away will people be?” A rough ladder:

• In the hand: A6 or A5. Fits a letterbox, a counter and a coat pocket.
• On a noticeboard or door: A4 or A3, read from a step or two back up to a few metres.
• Across a room or pavement: A2 or A1. Shop windows, pavement A-boards and posters.
• From a car or across a car park: A1 or A0 boards for sites, events and open days.

If it will be read from further still, the A series stops being the right tool; what size poster covers larger non-A formats, and sign text size explains how big your letters need to be for the distance.

Quick recap of A series paper sizes #

Each size is half the one above and the same shape, A4 is 210 × 297 mm, add 6 mm each way for bleed, and choose the size by reading distance. Still stuck between two A series paper sizes for your wall or window? Measure the space and get in touch.