BMI, BMR, TDEE and Calorie Estimates: What Each Number Means

Health calculators can organize measurements into useful estimates, but different calculators answer different questions. They are planning and screening tools, not diagnoses.

BMI relates weight to height

Body Mass Index uses weight relative to height squared. It is commonly used as a population level screening measure. BMI does not directly measure body fat and does not account for every difference in body composition, age, pregnancy status or health condition.

BMR estimates energy use at rest

Basal Metabolic Rate estimates the energy the body would use at rest under defined conditions. It is calculated from variables such as weight, height, age and sex depending on the equation used. It is not a direct measurement of an individual's metabolism.

TDEE adds activity to an energy estimate

Total Daily Energy Expenditure usually starts with an estimated resting energy need and applies an activity factor. Because activity categories are broad, the result is an estimate. Two people who choose the same activity label can still have different real world energy expenditure.

Calorie targets depend on the goal and the person

A calorie calculator may use estimated energy needs plus a chosen surplus or deficit. That makes the output useful for planning, but it does not account for every medical, nutritional or behavioral factor. Symptoms, eating disorders, pregnancy, medication effects and individualized treatment require professional guidance.

Related calculators

Health calculator results are educational estimates. For diagnosis, treatment, medication, pregnancy concerns or individualized nutrition decisions, use an appropriate healthcare professional.