Paper reference data.

What is in the reference?

This collection combines published nominal dimensions with our calculated conversions. It covers A0, A1, A2, A3, A4, A5, A6, US Letter and US Legal. The downloads include portrait dimensions in millimetres and inches, area in square metres, estimated mass at 80 gsm, image dimensions at 300 PPI, and every portrait fit-scale pairing between these nine formats.

The numeric values are available for reuse. When citing nominal sizes, refer to the source standard or published reference. When citing the conversion tables, link to this page so readers can inspect the method. The downloads contain factual dimensions and our calculations, rather than a copy of the ISO standard.

Use the tables in data tools

The CSVW metadata describes each column's type and units, identifies rows and connects both scale-format columns to the dimensions table. Each sidecar includes the complete two-table group, so a compatible validator can resolve those references. The existing CSV and complete JSON downloads are unchanged.

• Dimensions CSV metadata
• Scale matrix CSV metadata

The metadata files follow the W3C CSVW recommendation. They describe how to read the existing data; they do not change the formulas, precision or production assumptions.

Reproduce an answer

Inches: divide millimetres by exactly 25.4. The CSV keeps six decimal places at most; the human reference pages generally show two.

Pixels: multiply physical inches by 300, then round to the nearest whole pixel. This represents image PPI, rather than a printer’s dot resolution.

Mass: multiply the nominal area in square metres by 80 grams per square metre. This excludes ink, packaging, binding and variation in real paper stock.

Scale: calculate both target-to-source dimension ratios and use the smaller. For A4 to A3, the result is approximately 141.414141%. The matrix assumes portrait orientation and no printer margins. Use the print scale calculator for an individual comparison.

Precision and limits

ISO A sizes are rounded to nominal whole-millimetre dimensions. Using an ideal square-root-of-two ratio for every conversion can therefore give a slightly different result. Manufacturing tolerance, printer margins and print-driver scaling are separate from these calculations.

The reference does not predict how many bleed-ready pieces fit on a larger sheet. For that task, use the print sheet layout planner, where bleed, margins and gaps are explicit inputs.

Sources

• ISO 216:2007, the standard for trimmed A-series formats.
• Adobe’s A-series reference, published nominal millimetre dimensions.
• Adobe’s document formatting reference, Letter and Legal dimensions.

The JSON download includes these source links and the calculation methods alongside the records, so provenance travels with the data.

Inspect constructed layouts

The 24-case layout benchmark adds margins, bleed, gaps and complete placement coordinates to a separate reproducible dataset. It includes an independent geometry verifier. For physical-size output, use the print worksheets and calibration references.