ISO A series / A3
A3 page size for PDF generation
A3 is two A4 sheets side by side, and it is what a document becomes when a table stops fitting.
The dimensions
One measurement in four units. Millimetres and inches are what a printer works in; points are what the PDF itself stores; pixels are only useful for checking a screen mock-up against the real thing.
- Millimetres: 297 x 420 mm
- Inches: 11.69 x 16.54 in
- Points: 842 x 1191 pt
- CSS pixels: 1123 x 1587 px at 96 dpi
Where the size comes from
A3 is A4 unfolded. That relationship is the practical reason it gets used: an A3 sheet folded once is an A4 booklet, and an A3 spreadsheet printed at 71 percent lands exactly on A4 with no cropping. The 71 percent is one over the square root of two, and it is the same number on every photocopier reduction button in the world.
What gets printed at this size
- wide financial tables that will not fit A4 without a font nobody can read
- engineering drawings, floor plans and anything dimensioned
- project timelines and Gantt output, which are wide by nature
- poster proofs, before they are scaled up for real printing
Margins that survive a real printer
20mm all round. The extra width invites people to fill it edge to edge, and A3 output is far more likely to be printed on a shared office device with a wider unprintable border than a desktop printer has. If the sheet will be folded to A4 for filing, keep 25mm clear of the centre fold line at 148.5mm from the left.
The CSS
A3 is one of the six named formats the render API accepts, so it can be set in the request options or in the document's own CSS. Setting it in CSS keeps the size with the template, which is usually what you want.
@page {
size: A3 portrait;
margin: 20mm;
}
/* Wide tables are the reason A3 was chosen. Let the table set its own
width rather than forcing it to 100 percent of a page it overflows. */
table {
width: auto;
min-width: 100%;
border-collapse: collapse;
}The render request
With a named format the size travels in the options and the CSS is optional.
{
"html": "<!doctype html>...",
"options": {
"format": "A3",
"margin": { "top": "18mm", "bottom": "18mm", "left": "16mm", "right": "16mm" }
}
}The mistake people make
Reaching for A3 landscape when the real problem is a table with too many columns. A landscape A4 is 297mm wide, which is exactly the width of a portrait A3, and it prints on the paper that is already in the tray.
Frequently asked
What is A3 in pixels?
1123 x 1587 px at 96 dpi, at the 96 pixels to the inch that CSS assumes. That number is useful for comparing a screen mock-up against the page, and useless for laying out the document: use 297 x 420 mm instead, because a page laid out in pixels shifts whenever the render scale changes.
Can I pass A3 as a format?
Yes. "A3" is one of the six format values the API accepts, alongside A4, A3, A5, Letter, Legal and Tabloid.
Does landscape need a different page size?
No. Landscape is the same rectangle turned, so it is set as an orientation rather than as swapped dimensions. Writing the width and height the other way round produces the same page and makes the intent harder to read later.
Other page sizes
Sizes that come up in the same conversation, and one from each of the other families.
A4 page size for PDF generation
A4 is the default page for business documents everywhere except North America, and the default this API uses when no format is given.
A5 page size for PDF generation
A5 is half an A4 sheet, and the right size for a document that is short enough that A4 looks empty.
A6 page size for PDF generation
A6 is postcard size, a quarter of an A4 sheet, and the smallest ISO size that still holds a paragraph comfortably.
B5 page size for PDF generation
ISO B5 sits between A5 and A4, and it is the standard book block size across much of Europe and Asia.
US Letter page size for PDF generation
Letter is 8.5 by 11 inches and it is the default page in the United States, Canada, Mexico, Chile and the Philippines.
4x6 shipping label PDF size
The 4 by 6 inch label is the standard thermal shipping label accepted by every major carrier, and the most common non-paper page size an API renders.
80mm thermal receipt PDF size
The 80mm roll is the standard point-of-sale receipt: 80 millimetres of paper, a printable width of about 72mm, and a length that depends on the order.
Every page size, with dimensions
The full list, grouped by what the size is for.
Paste the CSS below into the playground and see the page box it produces.