Our calculation path

From input to result

Each tool follows the same controlled path: sanitize and parse the input, confirm required values and supported ranges, check relationships between fields, normalize physical units, apply the method, reject non-finite outputs, classify only where a documented reference exists, then round for display.

Source hierarchy

We prioritize official standards and government guidance, then original scientific research, professional organizations, and peer-reviewed validation studies. A popular calculator website is not treated as an authoritative formula source.

Precision and confidence language

A population equation is not made more accurate by displaying six decimal places. Results use method-appropriate rounding and are labelled as calculated, derived, predicted, estimated, standardized, or exact. We avoid claims such as “guaranteed,” “perfect calorie need,” or “exact body fat.”

Population and youth safeguards

Adult BMI categories are applied only from age 20. Adult dieting, calorie-deficit and aggressive weight-change tools require users to be at least 18. We do not substitute adult rules for children or adolescents when the required age- and sex-specific reference data are not implemented.

Changing standards

Standards that can change are versioned and dated. The Army Body Composition tool uses Army Directive 2026-13 and the July 2026 waist-to-height ratio benchmark. The Army Fitness Test page references the scoring tables approved 15 May 2025 and effective 1 June 2025; its current implementation totals points already obtained from the applicable official table rather than inventing raw-score conversions.

Privacy by default

Calculator math runs locally in the browser. Age, weight, height, waist, heart rate and performance inputs are not sent to a calculation server and are not automatically written to local storage. Closing or reloading the page clears the entered values.

General limitation