Methods & sources

These tools are intentionally transparent about the equations, conversion factors, and input restrictions they implement. Successful arithmetic tests are not proof of individual clinical accuracy.

Resting energy: Mifflin–St Jeor

The BMR-labelled tool estimates REE using the simplified equation: 10 × weight(kg) + 6.25 × height(cm) − 5 × age + coefficient. The coefficient is +5 for the published male equation and −161 for the published female equation. See the original study.

We accept ages 19–78 to stay within the original study’s age range. That does not imply clinical validation for every accepted input combination. Height must convert to 90–250 cm and weight to 25–400 kg; these are software sanity limits. A non-positive estimate is rejected.

Daily energy: activity scenarios

The TDEE tool multiplies unrounded REE by 1.2, 1.375, 1.55, 1.725, or 1.9. These are disclosed heuristic scenarios, not individually measured factors or recommendations. They were not validated as part of the Mifflin equation. This is not the same model as the NIDDK Body Weight Planner.

Adult BMI

We divide kilograms by metres squared and apply CDC adult categories. The adult tool accepts ages 20–100. Categories use the unrounded value; the displayed BMI has two decimal places. Refer to CDC’s discussion of interpretation and limitations.

Unit conversions

One inch is 2.54 cm, one foot is 12 inches, one pound is 0.45359237 kg, and one stone is 14 pounds. Energy uses 1 kcal = 4.184 kJ. We convert measurements before applying health equations. See NIST’s SI guide and FAO’s energy-conversion reference.

Macro calorie totals

We use 4 kcal/g protein, 4 kcal/g carbohydrate, and 9 kcal/g fat. The tool does not model alcohol, fibre, polyols, or specific food factors separately. It does not prescribe a macro split. Read the FAO discussion of general and specific factors.

Verification and precision

Calculations use full numerical precision internally and round for display. The implementation is checked against fixed worked examples, equivalent metric and imperial inputs, category boundaries, and invalid entries. These checks establish software behaviour, not personal medical accuracy. The articles and tools have not been independently clinically reviewed.