Mifflin-St Jeor vs. Harris-Benedict: Which BMR Equation Is Better?
October 21, 2026
Both equations estimate basal metabolic rate from weight, height, age, and sex, but they were derived from different populations. The Mifflin-St Jeor equation (1990) is generally considered more accurate for modern adults, which is why most dietitians start with it. The revised Harris-Benedict equation tends to run a little higher. For an 80 kg, 180 cm, 35-year-old man, Mifflin-St Jeor gives about 1,755 kcal per day and Harris-Benedict about 1,825.
Skip the math and get your answer instantly:
Open the BMR Calculator →The Two Formulas
Mifflin-St Jeor: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 for men, or − 161 for women. Revised Harris-Benedict for men: 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age. For women: 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age.
Both use the same inputs, so switching between them only changes the output by a few percent.
| Person | Mifflin-St Jeor | Harris-Benedict (revised) |
|---|---|---|
| Man, 35, 80 kg, 180 cm | 1,755 kcal | 1,825 kcal |
| Woman, 35, 65 kg, 165 cm | 1,345 kcal | 1,408 kcal |
Which Is More Accurate?
Studies comparing predictive equations against measured resting energy expenditure have found Mifflin-St Jeor within 10% of measured values for a larger share of people than other common equations. That is why the Academy of Nutrition and Dietetics has favored it for healthy adults.
Neither equation accounts for body composition. A muscular person burns more at rest than the formula predicts, and a person with very high body fat may burn less. If you know your lean mass, equations such as Katch-McArdle can be more precise.
How to Use the Result
Treat BMR as a starting estimate, not a fixed fact. Multiply it by an activity factor to get your daily energy needs, then track your weight for two to three weeks and adjust by 100 to 200 calories depending on what actually happens.
A difference of 70 calories between formulas is smaller than the day-to-day variation in food labeling and portion sizes, so do not overthink which equation you choose. Pick one and stay consistent.
Frequently Asked Questions
Which BMR equation is most accurate?
For most healthy adults, Mifflin-St Jeor has the best track record. It was validated on more recent populations than the original Harris-Benedict equation.
Why do equations give different results?
They were built from different groups of people and measurement methods, so their coefficients differ. The gap is usually under 5% to 10%.
Does BMR change with age?
Yes. Both equations subtract calories for each year of age, and muscle loss with age also lowers resting energy expenditure.
Should I use BMR or TDEE to set calorie goals?
Use TDEE, which includes activity, to set targets. BMR alone is the minimum for basic body functions and is too low to eat at for most people.