Methodology

Each formula ships with test cases whose expected values come from published, authoritative sources — never self-generated. A calculator cannot be published until those tests pass.

We cite primary authorities only: government agencies, standards bodies, and peer-reviewed research. Every figure that can change over time carries the source and the data year.

Jurisdiction data — tax brackets, contribution limits, and similar figures — is reviewed on a fixed schedule and updated within the first two weeks of each year.

Displayed precision is stated on each result. All numbers are formatted for your locale; the underlying calculation uses full precision.

Spotted an error? Every page links its sources so you can check our work, and corrections are logged with the review date.