Sources and methods

Resting energy

The BMR calculator uses the Mifflin–St Jeor equation for estimated resting energy expenditure. The original study included adults aged 19 to 78. Results for older ages extrapolate beyond that study group.

Daily maintenance calories

We multiply the unrounded resting energy estimate by the chosen activity factor. The FAO/WHO/UNU report describes physical activity level as a ratio of total energy expenditure to basal metabolic rate. The five factors in our tool, from 1.2 to 1.9, are calculator assumptions. The report uses different ranges, and the factors are not measured from your steps or workouts.

Adult BMI

BMI is weight in kilograms divided by height in metres squared. We compare the unrounded result with the CDC adult BMI cutoffs for people aged 20 or older.

Food measurements

The roti calculator uses USDA FoodData Central SR Legacy records for “Wheat flour, whole-grain” and “Butter oil, anhydrous” (search the names on fdc.nal.usda.gov). A package label can give a closer estimate for a specific brand of atta or ghee.

Body shape, nutrition reference and training calculators

Each calculator in the tools directory lists its source at the bottom of the page: NICE NG246 for waist-to-height ratio, the 2008 WHO consultation for waist-to-hip ratio and waist cut-offs, Hodgdon and Beckett (1984) and the American Council on Exercise for the Navy tape-measure body-fat estimate, Devine (1974), Robinson (1983) and Miller (1983) next to the CDC healthy BMI band for the historical weight formulas, the National Academies Dietary Reference Intakes for protein and water, the Compendium of Physical Activities for MET values, Tanaka et al. (2001) with CDC percentage zones for heart rate, and Epley (1985) and Brzycki (1993) for one-rep max. None of these tools diagnose a condition, suggest medicine doses or set weight-loss targets.

Report a correction if you spot a discrepancy.