PDFPipe

North American sizes / Letter

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.

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: 215.9 x 279.4 mm
  • Inches: 8.5 x 11 in
  • Points: 612 x 792 pt
  • CSS pixels: 816 x 1056 px at 96 dpi

Where the size comes from

Letter predates the metric standardisation the A series came from and it has no geometric relationship to anything. Half a Letter sheet is 5.5 by 8.5 inches, which has a different aspect ratio from the sheet it came from, so Letter does not scale down cleanly the way A4 does. That single fact explains most of the friction between the two systems.

What gets printed at this size

  • any document whose reader is in North America
  • tax and government forms, which are defined at this size
  • legal correspondence in every US jurisdiction except court filings that specify Legal

Margins that survive a real printer

1 inch all round is the convention and it is what every word processor defaults to. In millimetres that is 25.4mm, which is noticeably wider than the A4 convention of 16 to 18mm, so a document that looks correctly proportioned on A4 will look under-margined on Letter and the reverse.

The CSS

Letter 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.

css
@page {
  size: Letter portrait;
  margin: 1in;
}

/* Letter is 6mm wider and 18mm shorter than A4. A layout that fits one
   exactly will overflow or come up short on the other, so avoid fixed
   heights anywhere near the page height. */

The render request

With a named format the size travels in the options and the CSS is optional.

json
{
  "html": "<!doctype html>...",
  "options": {
    "format": "Letter",
    "margin": { "top": "18mm", "bottom": "18mm", "left": "16mm", "right": "16mm" }
  }
}

The mistake people make

Serving one PDF to both markets. Letter is shorter than A4 by 17.6mm, so an A4 document printed on Letter loses the bottom of the last page, and a Letter document printed on A4 leaves a band of white. If both audiences matter, render twice and pick by the recipient's country.

Frequently asked

What is Letter in pixels?

816 x 1056 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 215.9 x 279.4 mm instead, because a page laid out in pixels shifts whenever the render scale changes.

Can I pass Letter as a format?

Yes. "Letter" 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.

Paste the CSS below into the playground and see the page box it produces.