Is Mifflin-St Jeor the most accurate formula available?

It's one of the better-validated equations for the general population, though no formula perfectly predicts an individual's actual metabolism — treat the result as a solid starting estimate.

Why is my BMR so much lower than my TDEE?

BMR only covers calories burned lying still. TDEE adds in movement, exercise, and daily activity, which for most people is a substantial multiplier on top of BMR.

How was the Mifflin-St Jeor equation developed?

Researchers measured resting energy expenditure by indirect calorimetry in 498 healthy adults and fit a regression equation to the results — it's since become one of the standard formulas used in clinical nutrition.

Does this work for children or pregnant women?

No — it was derived from and validated on healthy non-pregnant adults, so results for children, teens, or pregnant women aren't reliable. Those groups need age- or condition-specific guidance from a clinician.

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Health & Fitness

Calorie Calculator

BMR and daily calorie needs (Mifflin-St Jeor).

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About the Calorie Calculator

Estimates your Basal Metabolic Rate (BMR) — the calories your body burns at complete rest — then scales it by your activity level to estimate total daily calorie needs (TDEE), using the Mifflin-St Jeor equation, one of the more widely validated formulas for this.

How to use it

Select your Sex.
Enter your Age, Height (cm), and Weight (kg).
Choose the Activity level that best matches your typical week.
Read your BMR and TDEE (daily calories) instantly in the result panel.

Formula

Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
TDEE = BMR × activity multiplier

Mifflin-St Jeor equation (Mifflin et al., 1990), derived from indirect-calorimetry measurements of 498 adults and one of the better-validated resting-energy-expenditure formulas for the general population.

Worked example

A 30-year-old man, 175cm, 75kg, moderately active (1.55×): BMR is about 1,724 calories, and TDEE comes to roughly 2,672 calories a day.

Recommendations

• Re-run this periodically as your weight changes — BMR shifts with it, so last month's number can drift.
• When unsure between two activity levels, pick the lower one — most people overestimate how active they actually are.
• Feed the TDEE result into the TDEE Calculator to get concrete cutting, maintaining, or bulking targets.

Frequently asked questions

Metabolic rate naturally declines with age and differs by sex due to average differences in muscle mass and body composition — the formula adjusts for both.

Related tools

TDEE Calculator

Macro Calculator

BMI Calculator

Sources

Mifflin MD, St Jeor ST, et al. — A new predictive equation for resting energy expenditure in healthy individuals (Am J Clin Nutr, 1990) — accessed 2026-08-19

Disclaimer

Educational estimate, not medical advice. Consult a qualified clinician before making health decisions.