A4 vs Letter: Exact Paper Sizes and Differences

November 4, 2026

The difference between A4 and Letter is small but easy to notice: A4 is 210 × 297 mm (8.27 × 11.69 inches), and US Letter is 8.5 × 11 inches (215.9 × 279.4 mm). So A4 vs Letter comes down to A4 being 17.6 mm taller and Letter being 5.9 mm wider. A4 is the standard almost everywhere; Letter is used in the United States, Canada, the Philippines and parts of Latin America.

That gap matters most when a document crosses between the two: an A4 PDF printed in the US, or a Letter form sent to Europe. Below are the exact sizes in every unit you’re likely to need, and how to print one on the other without cutting anything off.

A4 paper size and Letter size, in every unit

The A4 paper size comes from the international standard ISO 216. Letter is defined by the American standard ANSI/ASME Y14.1, where it’s called ANSI A. Points are the unit PDFs use (1/72 of an inch), and pixel sizes are what a scan of the full page has at each resolution.

A4’s shape has a useful property: its height is √2 times its width, so folding or cutting it in half gives A5 with the same proportions, and two A4 sheets side by side make A3. Letter doesn’t scale that way, which is why US paper sizes (Letter, Legal at 8.5 × 14 in, Tabloid at 11 × 17 in) don’t share one shape.

Letter size vs A4: what’s different in practice

• Margins move. A Word or Google Docs file set up on A4 and printed on Letter loses about 17.6 mm of height. If the printer doesn’t scale it, the bottom lines spill onto a second page or get cut off.
• Ring binders and folders differ. A4 sheets stick out of Letter folders by more than a centimeter at the top, and Letter sheets sit a little loose in A4 sleeves.
• Forms are drawn for one size. A government form designed on Letter has boxes in fixed places; printed on A4 at 100%, it loses about 3 mm at each side and ends 17.6 mm before the bottom of the sheet.
• Scans have different shapes. A scan of a whole Letter page is wider in proportion than an A4 scan, so placing one on the other’s sheet leaves a white band.

Which countries use A4 and which use Letter?

Letter is the everyday size in the United States, Canada and the Philippines. The Unicode CLDR locale data, which phones and computers use to pick a default paper size, also lists Mexico, Chile, Colombia, Costa Rica, El Salvador, Guatemala, Nicaragua, Panama, Puerto Rico, Venezuela and Belize as Letter countries, as summarized in Wikipedia’s Letter article. Most other countries, including the UK, the EU, Australia, India, Japan and China, use A4.

Your computer picks its default paper size from your region setting, which is why a file made abroad sometimes opens on the “wrong” paper.

How to print an A4 PDF on Letter paper

1. Open the PDF and choose Print.
2. Set the paper size to Letter.
3. Choose the scaling option that fits the page to the paper. Its name depends on the app: Fit, Fit to page, Scale to fit, Shrink oversized pages, or Fit to printable area.
4. Print.

Fitting an A4 page onto Letter scales it to 94% (279.4 ÷ 297), limited by the height. Text gets a little smaller, and the narrower page leaves about 18.3 mm of extra white across the width, roughly 9.2 mm at each side. If you print at Actual size instead, the page keeps its size and about 8.8 mm is cut from the top and the bottom.

Going the other way, a Letter page fitted to A4 scales to 97% (210 ÷ 215.9), limited by the width. At actual size only 2.95 mm would be lost at each side, which is often inside the margin the printer can’t print on anyway.

Scanning to A4 or Letter

Most phone scanners save each page at the shape of the paper you photographed and then place it on a sheet in the PDF. Copier places every page on an A4 sheet in its PDFs, turned to landscape for wide pages, and fits the page to the sheet so nothing is cropped. A Letter page scanned with Copier fills the width of the A4 sheet, with a white band of about 12.6 mm at the top and the bottom. When you print that PDF on Letter paper with Fit to page, the sheet is scaled to 94%, so the original page comes out at about 91.5% of its real size. That’s fine for reading and filing. If a form has to print at exactly its real size, hold a test print against the original before you rely on it.

If you’re scanning US legal papers, scanning legal-size documents covers the longer 8.5 × 14 inch sheets.

Tips for working across both sizes

• Before you send a document abroad, export it as a PDF. A PDF keeps its page size, so the other person sees exactly what you laid out and can choose how to print it.
• If you design a form for both, keep everything inside 210 × 279.4 mm, the area A4 and Letter share. It then prints at 100% on either.
• When printing someone else’s PDF, use fit-to-page unless the document says to print at actual size, as some forms and tickets with barcodes do.
• For scans, the paper size matters less than the resolution. Best DPI for scanning documents and PDF vs JPG cover the choices that change how a scan looks and prints.