If you’re sending a file to a printer, the number to have in front of you is 594 x 841 mm (23.39 x 33.11 inches). That’s A1, the second largest sheet in the ISO 216 A series.
It’s half an A0 and twice an A2, which works out to half a square metre of paper.
Posters are the obvious use. Architects print technical drawings on it too, and plenty of meeting rooms run flip charts at roughly this size.
One catch for poster work. ISO 216:2007 sets these dimensions, but the standard itself says it does not necessarily apply to posters (ISO, 2007), so it doesn’t necessarily govern the poster itself.
How big is A1 paper in millimetres, centimetres and inches?
In centimetres it’s 59.4 x 84.1, and in inches 23.39 x 33.11 (often rounded to 23.4 x 33.1). Millimetres are the real definition though. Every other unit is a rounded conversion of 594 x 841 mm, and the area comes to 0.4996 m2, effectively half a square metre.
These values match the ISO 216 size table published by papersizes.org.
Width comes first in the notation, so 594 x 841 mm is the portrait sheet. Turn it sideways and it becomes 841 x 594 mm, still the same A1.
Inch values differ between sources because 594 / 25.4 gives 23.386 and 841 / 25.4 gives 33.110. Some pages also print 59.5 cm, which is a typo for 59.4.
How exact is a printed A1 sheet?
Not as exact as the numbers suggest. Mills do not cut to the exact millimetre. ISO 216 allows a deviation of +/- 2 mm on dimensions between 150 and 600 mm and +/- 3 mm above 600 mm, according to the tolerance table in Markus Kuhn’s ISO 216 summary.
For A1 that puts the 594 mm side under the 2 mm rule and the 841 mm side under the 3 mm rule.
Some print-shop pages quote +/- 1.5 mm for A1. That tolerance covers dimensions up to 150 mm only, so it fits A6 and smaller.
DIN 476 is tighter, at +/- 1.5 mm for dimensions between 150 and 600 mm and +/- 2 mm above 600 mm. If you’re cutting a mount or a frame rebate, measure the actual sheet first.
Why is A1 exactly half of A0?
Start with A0, which is defined as 1 m2, and cut it in half across the long side. That cut is A1, so it holds half a square metre.
Both A1 measurements fall out of it. The 841 mm height equals the width of A0, and the 594 mm width is half of A0’s 1189 mm height (594.5 mm, rounded down).
Only one rectangle shape keeps its proportions when halved, and its long side equals the short side times the square root of 2. Rounding to whole millimetres shifts the A1 figures slightly, since 841 / 594 gives 1.416, not 1.414.
The B and C series use the same ratio, so the whole family of international paper sizes scales without distortion.
Where the 1:sqrt(2) ratio comes from
Georg Christoph Lichtenberg described the ratio in a letter to Johann Beckmann on 25 October 1786, the oldest preserved written reference to it (Markus Kuhn’s archived copy of the letter).
Walter Porstmann turned the idea into a full system of sizes tied to the square metre in the early 20th century. DIN 476 then introduced that system in Germany in 1922 and replaced a wide variety of older formats (NRICH, University of Cambridge).
ISO’s catalogue lists ISO 216:2007 as the current edition, last confirmed in 2021, with the 1975 edition withdrawn.
ISO 216 says it doesn’t necessarily apply to posters, which can fall under separate standards. A1 is a common poster sheet, but that doesn’t make the standard the rule for the poster.
A1 compared with A0, A2, A3 and A4
Cut an A1 sheet in half and you get two A2. Keep going and it’s four A3 or eight A4 sheets. Go the other way and A1 is half of an A0.
| Format | Size (mm) | Size (inches) | Relation to A1 |
|---|---|---|---|
| A0 | 841 x 1189 | 33.1 x 46.8 | Twice the area |
| A1 | 594 x 841 | 23.4 x 33.1 | Reference sheet |
| A2 | 420 x 594 | 16.5 x 23.4 | Half the area |
| A3 | 297 x 420 | 11.7 x 16.5 | One quarter, 4 per A1 |
| A4 | 210 x 297 | 8.3 x 11.7 | One eighth, 8 per A1 |
Sizes follow the ISO 216 table published by papersizes.io.
Above A1 sits the A0 sheet it is cut from, at 841 x 1189 mm. DIN 476 goes bigger still with 2A0 (1189 x 1682 mm) and 4A0 (1682 x 2378 mm), neither of which ISO 216 defines, per papersizes.org.
At the small end, A1 has eight times the area of a standard A4 office sheet. Its long side is 2.83 times longer.
Scaling A1 to other sheets
Every A sheet shares one ratio, so a copier scales between them without cropping. Markus Kuhn’s ISO 216 summary gives the linear factors from A1 as 141% to reach A0, 71% for A2, 50% for A3 and 35% for A4.
The drop to A4 is where drawings fail. A 10 pt label on an A1 sheet prints at 3.5 pt on an A4 reduction.
Is A1 the same as 24 x 36 inches?
No. A1 measures 23.39 x 33.11 inches, so a 24 x 36 inch sheet is 0.61 inches wider and 2.89 inches taller.
| Sheet | Size (mm) | Size (inches) | Compared with A1 |
|---|---|---|---|
| A1 | 594 x 841 | 23.39 x 33.11 | Reference sheet |
| ANSI D | 559 x 864 | 22 x 34 | 35 mm narrower, 23 mm taller |
| ARCH D | 610 x 914 | 24 x 36 | 16 mm wider, 73 mm taller |
ANSI D and ARCH D dimensions come from Archtoolbox’s North American size tables, which list no sheet at 594 x 841 mm.
By area the gap is smaller. A1 covers 0.4996 m2, ANSI D 0.483 m2 (about 3% less) and ARCH D 0.557 m2 (about 12% more), calculated from the sizes above.
Shape differs more than area does. The long side of A1 is 1.416 times the short side, against 1.5 for ARCH D and 1.545 for ANSI D.
What happens when one is swapped for the other
Scale A1 artwork to the 24 inch width and it comes out at 24 x 34 inches, which leaves a 2 inch empty strip on a 36 inch sheet. Scale it to the 36 inch height instead and it grows to 25.4 inches wide, so about 1.4 inches gets cropped from the width.
Moda’s size reference calls A1 close to the US 24 x 36 inch poster but not identical, and 4OVER4 lists 24 x 36 as its standard wall poster. Both match the arithmetic above.
Build the file at the size the printer lists. Treat A1 and 24 x 36 as two separate jobs.
What is A1 paper used for, and when does it not fit?
Wall posters are the big one, along with flip chart paper and technical drawings. It stops working where a printer, pad or frame was built for a slightly different sheet.
Posters and large prints
Paperlust’s size-by-distance table pairs A1 with viewers standing 2 to 4 m away, in a hallway or at an event stand.
That reach explains why conference poster sessions often specify A1, as Moda’s size reference notes. Quill lists advertising circulars and annual year planners as common jobs too, plus large-scale presentations.
Where A1 sits among the other formats printers sell as posters is laid out in this overview of poster sizes.
Flip chart pads
Pads sold as A1 are 580 x 810 mm at Nobo and 585 x 810 mm at Bi-Office, against 594 x 841 mm for the ISO 216 sheet. That makes them 9 to 14 mm narrower and 31 mm shorter. A poster printed at the full ISO size overhangs the pad on an easel.
Size guides that call A1 the standard flip chart format are right about the use and loose about the dimensions. Build easel material at the pad’s own size, not at 594 x 841 mm.
Technical drawings
ISO 5457:1999 sets the trimmed A1 drawing sheet at 594 x 841 mm, with a drawing space of 574 x 811 mm inside the frame. The untrimmed sheet is 625 x 880 mm and gets cut down after printing. Borders are 20 mm on the left edge including the frame, and 10 mm on the other three sides.
The drawing space is 20 mm smaller on the short side and 30 mm smaller on the long side, so content drawn out to the sheet edge does not fit inside the frame. The title block sits in the bottom right corner of that space.
When a smaller sheet does the job
Paperlust lists A2 or A1 for wall posters read from 1 to 2 m. If the nearest viewer stands closer than that, A1 is larger than the job calls for.
Printing is the second limit. Adobe’s A1 format guide says a high-quality single-sheet print needs a specialist large format printer, so without one the job goes to a print shop.
For anything read at arm’s length, A2 is the better default.
A1 paper size in pixels at 72, 150 and 300 PPI
At 300 PPI an A1 file is 7016 x 9933 px. Halve the resolution to 150 PPI and it’s 3508 x 4967 px, and at 72 PPI it drops to 1684 x 2384 px.
| PPI | Pixels (width x height) | Megapixels | Typical use |
|---|---|---|---|
| 72 | 1684 x 2384 | 4.0 | Equals points (pt) |
| 150 | 3508 x 4967 | 17.4 | Wall posters, drawings |
| 300 | 7016 x 9933 | 69.7 | Close-reading detail |
Pixel values follow papersizes.io and Moda. Megapixel counts are calculated from them.
Each figure is 594 mm or 841 mm divided by 25.4, then multiplied by the PPI. For any other resolution, run the sheet through a tool that can convert millimetres to pixels.
Why the pixel figures differ between sources
Rounding accounts for a 1 px gap at most. Two published figures miss by more than that.
Snap Australia’s guide lists 4961 for the 150 PPI height, where Paperlust and Moda list 4967. The arithmetic (841 / 25.4 x 150) gives 4966.5, which some tools round down to 4966, and Snap’s own A0 line gives 4967 as the A0 width, the same edge as the A1 height.
Quill prints 1,648 for the 72 PPI width. That’s a typo for 1,684, the value papersizes.io lists in both pixels and points.
Gaps of 6 px and 36 px are errors, not rounding.
Which resolution should an A1 file use?
Printers disagree on the right PPI for A1.
Printing.com recommends 150 dpi as the maximum for large format posters and says anything higher makes no difference to the print but slows processing. Ellerhold’s A1 poster data sheet asks for 300 DPI at 1:1 size, and the University of Exeter’s print services guide asks for 300 dpi images. 4OVER4 treats 300 DPI as its standard but says very large prints viewed from a distance can drop to around 150 DPI at final size without looking soft.
Paperlust reports that a 300 dpi file is four times larger than a 150 dpi one with no visible gain at wall distance. SmartPress gives the same 150 figure for large posters.
Follow the printer’s own spec first. With none given, 150 PPI at final size is enough for A1 seen from 2 m or more, and 150 to 200 PPI suits viewing at 1 to 2 m. Keep 300 PPI for fine text, hairline rules and barcodes.
The wider logic behind those targets is covered in this explainer on the resolution standards used across print work.
Source images are the usual failure point. A 12 megapixel phone photo (4032 x 3024 px) reaches about 122 PPI at A1, calculated from its long side.
That sits inside Paperlust’s 100 to 150 dpi band for A1 in a hallway or at an event stand. It falls short of the 150 to 200 dpi Paperlust advises for small readable text.
How to set up an A1 file for print
Most reprints come from skipping one of these steps, so it’s worth doing them in order.
- Get the printer’s spec sheet first, because resolution, margins and PDF standard differ between providers.
- Set the document to 594 x 841 mm (portrait) or 841 x 594 mm (landscape), working in millimetres.
- Add 3 mm bleed on all four edges.
- Keep text and logos 15 mm inside the trim edge.
- Place images at 100% scale at the PPI the printer specifies.
- Convert greyscale images to four-channel CMYK so black stays colour-neutral, as printing.com advises for large format.
- Embed fonts or outline large headlines, then export one PDF per design in the printer’s format, such as PDF/X-4 (version 1.6) at Ellerhold.
Providers split on how bleed enters the file. Printing.com asks for a page size that includes it, while Ellerhold wants the 594 x 841 mm end format with bleed set in document setup rather than added to the page.
Skip bleed and trimming can leave a white sliver along the edge. The reasoning is covered in this guide to bleed in print design.
The 15 mm margin is Ellerhold’s recommendation for A1, while Exeter asks for only 3 mm between text and edge. Taking the larger figure satisfies both, and safe zones in print layouts explains how the margin works.
Choosing a roll width
| Roll | Canon driver setting | Fit for A1 |
|---|---|---|
| 594 mm | A1/A2 Roll (594.0 mm) | Portrait, full width |
| 609.6 mm | 24 in Roll (609.6 mm) | Portrait, 15.6 mm spare |
| 841 mm | A0/A1 Roll (841.0 mm) | Landscape, full width |
Canon’s imagePROGRAF PRO-6100S manual lists all three roll widths and rates borderless printing as recommended on each.
Ask the shop which roll it runs before finalising orientation.
Where A1 files go wrong
Bleed gets built into the page size when the printer adds its own. A landscape file lands on a portrait job.
Images are placed above 100% scale, which cuts their real PPI, and text gets set inside the bleed instead of inside the margin.
A1 Paper Size FAQ
Is the A1 envelope size the same as A1 paper?
No. The US envelope series lists its own A1 at 92 x 130 mm (3.62 x 5.12 inches), according to papersizes.io.
It is a small envelope with no connection to the 594 x 841 mm ISO sheet.
How much does an A1 sheet weigh?
At 80 gsm, an A1 sheet weighs about 40 g, calculated from its 0.4996 m2 area.
Heavier poster stock scales the same way, so 170 gsm comes to roughly 85 g.
Is B1 bigger than A1?
Yes. B1 measures 707 x 1000 mm, per Markus Kuhn’s ISO 216 summary, which puts it between A0 and A1.
The B series takes the geometric mean of adjacent A sizes, so each B sheet lands between two A sheets.
Does Japan use a different A1 size?
No. The Japanese standard JIS P 0138-61 defines the same A series as ISO 216, so A1 is still 594 x 841 mm there.
Only the Japanese B series departs from the ISO version.
How do you fold A1 down to A4?
Fold it in half three times, each fold parallel to the short edge.
The sheet goes to A2, then A3, then A4, and the shared ratio keeps every edge square with no trimming.
What to Check on an A1 Proof Before the Full Run
Start by measuring the sheet with a steel rule, because a wrongly scaled sheet makes every other check meaningless. After that, read the print from the distance it will hang at, and look at text clearance on all four edges last.
Sharpness is the one people get wrong. Never judge it at arm’s length. Paperlust notes that a 100 DPI A1 poster looks sharp in context, while a 100 DPI A3 looks slightly soft in the hand.
A reduced proof misleads for the same reason. Halving A1 to A3 turns a 150 PPI file into 300 PPI on the page, so softness the full sheet will show disappears.
A full-size proof costs one A1 sheet and some waiting, but it is the only proof that shows true sharpness.
Renowned for his expertise in logo design and visual branding, Bogdan has developed a multitude of logos for various clients.
His skills extend to creating posters, vector illustrations, business cards, and brochures. Additionally, Bogdan's UI kits were featured on marketplaces like Visual Hierarchy and UI8.
He also wrote in the past years on sites like Design Your Way, WebDesignerDepot, WPDean, Designmodo, Speckyboy, Slider Revolution, and more.
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Bogdan Sandu is a seasoned designer who has been designing websites since 2008. Renowned for his expertise in logo design and visual branding, Bogdan has developed a multitude of logos for various clients. His skills extend to creating posters, vector illustrations, business cards, and brochures. Additionally, Bogdan's UI kits were featured on marketplaces like Visual Hierarchy and UI8. He also wrote in the past years on sites like Design Your Way, WebDesignerDepot, WPDean, Designmodo, Speckyboy, Slider Revolution, and more.
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