Accuracy policy

Check the tool, not just the number

Each tool names its model, accuracy, sources, and assumptions under “How we got this.” Its warnings may narrow where a result applies. Check the input units and the source edition before using an answer. A displayed decimal is not a promise that every digit is accurate.

What the test numbers mean

The verification reports give each tool's largest observed error against its published test vectors and the tolerance used to judge those vectors. The observed error covers the tested inputs and sources; it is not a guarantee for every possible input. The tool page links its downloadable vectors, with sources and tolerances, so you can inspect the cases behind the report.

Stable and experimental

A Stable tool has passed the full verification bar, including an independent worked example, bounds checks, invariants, and comparison with a reference implementation. An Experimental tool has not passed every part of that bar. Both statuses describe testing, not certification or fitness for an operational decision. The current status appears on each tool page.

Limits and corrections

Models simplify reality, and reference data can age. A tool's stated assumptions, range, warnings, and source date are part of its accuracy claim. Check the sources ledger for editions and review dates, the known issues for confirmed problems, and the changelog for published result changes. If a result looks wrong, use “Report a problem” on that tool.

These results are planning, engineering, and education aids. Verify operational values against official sources; see the full disclaimer.