What Is 8.5 x 11 Paper? | The Standard US Letter Size

8.5 x 11 paper is the standard US Letter size, officially known as ANSI A, and it measures exactly 8.5 by 11 inches.

8.5 x 11 paper is the everyday office sheet in the United States and Canada. It’s what feeds through home printers for school assignments, business letters, and tax forms. The dimensions translate to 215.9 by 279.4 millimeters, which makes it slightly wider and shorter than the international A4 standard used almost everywhere else.

Why 8.5 x 11 Inches Is Called Letter Size

Letter is the official name for this sheet, and the ANSI/ASME Y14.1 standard assigns it the code ANSI A. The size became the U.S. government standard in the early 1980s when federal forms were standardized to Letter, replacing a smaller 8 x 10.5 inch “Government Letter” sheet that had been in use before.

The practical result is that 8.5 x 11 is the default paper size for virtually every printer, copier, and filing cabinet sold in North America. When you buy a ream of “copy paper” at a U.S. store, you’re buying Letter size unless the package says otherwise.

How 8.5 x 11 Compares to A4 and Other Sizes

A4 paper, the international standard, measures 210 x 297 mm. That makes A4 taller and narrower than Letter, which is 215.9 x 279.4 mm. The difference is small but real: documents designed for one size can reflow or print with unexpected margins when the other is selected.

Other sizes in the U.S. system include Legal at 8.5 x 14 inches and Tabloid (also called Ledger) at 11 x 17 inches. Here’s how the common sizes stack up:

One common mistake is writing “8×11” when the standard is 8.5 x 11. That half-inch makes a real difference for margins and formatting. The Letter paper size standard documents the exact specifications and history behind the format.

What 8.5 x 11 Paper Is Used For

Letter size dominates U.S. offices and homes. It’s the default for business correspondence, school assignments, invoices, and most home printing tasks. The U.S., Canada, and the Philippines use it as their standard office sheet, and it appears variably across Latin America as well.

For creative work, 8.5 x 11 is also a common choice. If you’re shopping for art supplies, you’ll find watercolor and mixed-media pads cut to this exact dimension. Our roundup of the best 8.5 x 11 watercolor paper options covers which sheets hold up best for painting, sketching, and ink work without the hassle of trimming larger stock.

Why the Letter Size Matters for Printing

Matching your document’s paper size to the physical sheet in your printer is required for predictable results. A document formatted for Letter placed on A4 paper gets cut off or shifted; the reverse produces unwanted white borders. Most modern software defaults to the regional standard, so U.S. users rarely need to change anything.

The engineeringtoolbox.com office paper sizes reference and IBM’s page sizes and dimensions documentation both confirm the same figures. When you grab a sheet and see “8.5 x 11” on the package, you’re holding the single most widely used paper size in North America — a standard that has held steady for decades.