The formula
Published in 1990 by Mark Mifflin and Sachiko St Jeor, this equation replaced the older Harris-Benedict formula as the clinical standard, and the American Dietetic Association has endorsed it as the most reliable predictor for the general adult population.
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
Worked example
A 35-year-old woman, 165 cm, 68 kg: 10 × 68 + 6.25 × 165 − 5 × 35 − 161 = 680 + 1,031 − 175 − 161 = 1,375 kcal/day BMR. Multiply by an activity factor (say 1.55 for moderate activity) and her TDEE estimate is about 2,130 kcal.
The same numbers for a man add 166 kcal (the +5 versus −161 constant), reflecting average lean-mass differences at equal size.
Accuracy and limits
Validation studies put Mifflin-St Jeor within 10% of measured BMR for the largest share of people of any simple equation — but that still means a 1,500 kcal prediction could be 1,350 or 1,650 in reality.
It systematically misses for very muscular people (underestimates) and those with high body fat (overestimates), because it never sees body composition. If you know your body-fat percentage, Katch-McArdle handles those cases better.
Put it into practice: run your own numbers with the related calculator — free, instant, and nothing leaves your browser.
Frequently asked questions
Is Mifflin-St Jeor better than Harris-Benedict?
For most people, yes — head-to-head validation work consistently shows smaller average error, which is why clinical practice switched.
Does the equation work for athletes?
It tends to underestimate very lean, muscular athletes by 5–15%. Katch-McArdle with a measured body-fat percentage is the better tool there.
What activity factor should I use with it?
Most people overestimate. If you have a desk job and train 3–4 times a week, 1.4–1.55 is usually closer to truth than 1.725.
More guides
- What Is TDEE?
- What Is BMR?
- Harris-Benedict Calculator
- Katch-McArdle Calculator
- BMR vs TDEE: What's the Difference?
- What Are MET Values?
- What Is NEAT?
- The Thermic Effect of Food
- Activity Multipliers Explained
- What Is a Calorie?
- Metabolic Adaptation Explained
- The Calorie Deficit, Explained
- 500-Calorie Deficit
- 1,000-Calorie Deficit
- 300-Calorie Deficit
- How Many Calories to Lose 1 Pound a Week
- How Many Calories to Lose 2 Pounds a Week
- Reverse Dieting
- Maintenance Phase
- Calorie Cycling
- How Accurate Are TDEE Calculators?
- Not Losing Weight in a Calorie Deficit? 7 Real Reasons
- Is 1,200 Calories a Day Safe?
- Should You Eat Back Exercise Calories?
- How Long Does Metabolic Adaptation Last?
- Do You Burn Fewer Calories as You Lose Weight?
- Why Your Maintenance Calories Keep Changing
- Calorie Cycling vs Flat Deficit
- How to Avoid Muscle Loss on GLP-1 Medications
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990. [link]
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984. [link]