Calculation Methodology

Each calculator starts with a defined question and the smallest formula that answers it. Universal arithmetic relationships are implemented directly. Where a definition depends on a platform, regulation, or jurisdiction, the page should identify that scope and prefer an official primary source.

The tools do not silently supply changing tax rates, legal thresholds, or market assumptions. A value that cannot be kept current reliably is left as a clearly labelled user input.

Formula functions reject undefined divisions, non-finite values, impossible counts, and invalid rates instead of displaying NaN or Infinity. Automated tests cover representative results and important failure cases.

Calculations use the entered numeric values before display rounding. Currency selection changes formatting only; it does not convert exchange rates or alter the formula. All money inputs in one calculation must therefore use the same currency.

A review date changes only when a calculator, explanation, policy, or supporting test is materially checked or updated. Formula changes require a repeatable test with a known expected result.

To report an error, use the Contact page and include the calculator, inputs, displayed result, expected result, and supporting source where relevant. Do not send account credentials, tax identifiers, or payment information.

Calculations run in the browser and are not submitted to an FBM Calculators Hub database. Results remain estimates driven by the user's inputs and assumptions and do not replace financial, tax, legal, accounting, employment, or investment advice.