US Paper Sizes (Letter, Legal, Tabloid) vs A4

Understanding the US paper size chart — concept and principle

The United States and Canada use paper sizes defined in inches, while most of the world, including Korea, uses the ISO A series. Letter, Legal and Tabloid look similar to A4 and A3 but are not the same, which causes cut-off margins, odd scaling and wasted prints. Pick a size and the chart shows its exact dimensions in inches and millimetres together with the nearest ISO size, so you can set up documents, printers and design files correctly.

The two sheets nearly match, which is why A4 files printed on Letter get cut off at the bottom unless scaled to about 94 %.

How it is calculated

US sizes are defined in inches, and the millimetre values are exact conversions: mm = inches × 25.4. The sizes in the chart are Letter 8.5 × 11 in, Legal 8.5 × 14 in, Tabloid/Ledger 11 × 17 in, Executive 7.25 × 10.5 in and Half Letter 5.5 × 8.5 in. The "closest ISO" column names the A or B size with the most similar dimensions.

The principle

US sizes grew from traditional inch-based formats and are not built on a single ratio: Letter is 1 : 1.294, Legal 1 : 1.647. In the engineering drawing series of ANSI/ASME Y14.1, Letter is size A and Tabloid is size B, and each larger size doubles the area, but the shape alternates between two ratios. The ISO A series (ISO 216) uses a constant aspect ratio of 1 : √2 (about 1 : 1.414), so folding a sheet in half gives the next size with the same shape, and A0 has an area of one square metre. This is why A4 scales cleanly to A3 or A5, while Letter does not scale cleanly to Tabloid.

Worked example

Default selection: Letter.

Width: 8.5 in × 25.4 = 215.9 mm.
Height: 11 in × 25.4 = 279.4 mm.
Closest ISO size: A4 (210 × 297 mm).
Compared with A4, Letter is 5.9 mm wider and 17.6 mm shorter.
To print an A4 page on Letter without cropping, it must shrink to 279.4 ÷ 297 ≈ 94 % (before printer margins).

How to read the result

If you send files across borders, match the paper setting to the printer's stock, or choose "fit to page". Letter documents printed on A4 lose a little width; A4 documents printed on Letter lose some height unless scaled. Tabloid (portrait) and Ledger (landscape) are the same 11 × 17 in sheet.

Common mistakes

Assuming Letter and A4 are interchangeable in forms with tight margins.
Confusing Legal (8.5 × 14 in) with A4; Legal is much longer.
Treating ISO B5 (176 × 250 mm) and JIS B5 (182 × 257 mm) as the same.

Keep in mind: Dimensions are nominal sheet sizes. Printers, copiers and envelope standards add their own margins and tolerances, so check your device settings before large print runs.

Frequently asked questions

Is Letter the same as A4?

No. Letter is 215.9 × 279.4 mm; A4 is 210 × 297 mm.

What is the difference between Tabloid and A3?

Tabloid is 279.4 × 431.8 mm, A3 is 297 × 420 mm: A3 is wider, Tabloid is taller.

What size is Legal paper in millimetres?

215.9 × 355.6 mm.

Sources: ANSI/ASME Y14.1, Decimal Inch Drawing Sheet Size and Format · ISO 216, Writing paper and certain classes of printed matter — Trimmed sizes — A and B series

Checked 8 Nov 2026. ANSI/ASME Y14.1.

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