What This Calculator Does

BMR (Basal Metabolic Rate) describes energy used to support basic physiological functions under specific resting conditions. An online calculator cannot replace a controlled metabolic measurement, so this page compares three common equations, averages the available resting-energy estimates, and applies activity factors to derive TDEE (Total Daily Energy Expenditure).

The page shows Revised Harris–Benedict, Mifflin–St Jeor, optional Katch–McArdle, the available-formula average, and TDEE across five activity levels from sedentary to very active. It does not calculate a weight-loss or weight-gain target, read food logs, or model illness, medication, training cycles, or laboratory measurements.

When to Use It

• You want a first estimate of resting energy.
• You want to compare how common equations differ for the same inputs.
• You want to turn a resting estimate into TDEE under several activity assumptions.
• You need a starting number for a maintenance, fat-loss, or weight-gain plan that you can later calibrate.

The controls start at age 18, so this is intended as an adult planning reference. Do not rely on it alone for children or teens, pregnancy or breastfeeding, chronic illness, medication that affects appetite or metabolism, eating disorders, or unexplained weight change.

For editable protein, fat and carbohydrate percentages based on TDEE or your own calorie amount, continue to the maintenance calorie and macro calculator. All three energy shares are editable and must total 100%; example percentages are not a prescription.

Inputs Explained

Sex

Revised Harris–Benedict and Mifflin–St Jeor use separate male and female coefficient sets, so the selection changes those outputs. It is a formula parameter, not a complete description of sex-related physiology, gender identity, or health status.