The Formula
Women: BMR = 10W + 6.25H - 5A - 161
W is weight in kilograms, H is height in centimeters, and A is age in years. If a calculator accepts pounds, feet, and inches, it should convert those inputs before using the equation.
What The Equation Estimates
The equation estimates resting energy expenditure from body size, age, and the sex-specific constants in the formula. It does not directly measure metabolism and it does not include your daily activity level.
Worked Example
For a 30-year-old man at 80 kg and 180 cm, the estimate is 10 x 80 + 6.25 x 180 - 5 x 30 + 5 = 1,780 kcal/day. That number is a resting baseline before TDEE activity multipliers are applied.
Where TDEE Starts
TDEE calculators usually multiply the Mifflin-St Jeor BMR estimate by an activity factor. That activity factor is often the least precise part of the process because normal movement, work demands, and exercise volume vary widely.
Where Calorie Targets Start
A calorie target is one more step after TDEE. Maintenance keeps the estimate unchanged, a deficit lowers it, and a surplus raises it. The equation itself does not decide the goal.
Limitations
Body composition, illness, medications, pregnancy, growth, long-term dieting, endocrine conditions, and tracking error can all make real needs differ from the equation. Use the number as a starting estimate and calibrate with real-world trends.
Frequently Asked Questions
Is Mifflin-St Jeor a BMR formula?
It is commonly used to estimate resting energy needs and is often labeled as a BMR formula in online calculators.
Does the equation include activity?
No. Activity is added later through a TDEE multiplier.
Can I use pounds and inches?
Yes, if the calculator converts them to kilograms and centimeters before applying the equation.
Sources And Further Reading
- A New Predictive Equation for Resting Energy ExpenditureThe American Journal of Clinical Nutrition / PubMed
- Body Weight PlannerNational Institute of Diabetes and Digestive and Kidney Diseases