Where the numbers come from
A-series dimensions use nominal millimetre values for formats covered by ISO 216. Published dimensions, not idealised areas, are used in calculations. US Letter and Legal use their inch dimensions, converted at exactly 25.4 millimetres per inch.
Reference pages link to the relevant standard or a published manufacturer or software reference. The tools show their formulas and worked examples so you can check the arithmetic independently. This project is not affiliated with ISO, Adobe or a paper manufacturer.
Precision without false certainty
Inch conversions, pixel dimensions and calculator results are rounded for readability. The underlying nominal dimensions remain the calculation source. Paper manufacturing tolerances, printer margins, stock variation and finishing can affect a real job.
We keep physical sheets distinct from printed pages, and image PPI distinct from printer DPI. For critical dimensions, confirm the printer settings and measure a test print.
Your calculation inputs
The calculators used directly on this website work in your browser and do not upload your inputs. The optional remote MCP interface receives the calculation parameters sent by your connected client. Its public tools do not ask for credentials, personal documents or files. There is no account system, advertising or analytics added by this project. The hosting service can process data needed to deliver and secure the website.
Check an answer
Start with the sources and formula on the relevant tool page. If a result looks wrong, compare the units, orientation and sheet count first. The paper size chart lists the source dimensions used throughout this reference.