Mifflin-St Jeor Calculator
Basal metabolic rate from sex, weight, height and age
How it's calculated (Mifflin-St Jeor formula)
The Mifflin-St Jeor formula (1990) estimates basal metabolic rate from sex, weight, height and age:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
The result is in kcal/day: the energy used at rest. For your total requirement, multiply BMR by a physical activity factor.
How to interpret the result
The value is your basal metabolic rate in kcal/day. To estimate your daily requirement, multiply it by your activity level (sedentary ~1.2; active ~1.5-1.7).
- Calories ≈ requirement → tend to maintain weight.
- Calorie deficit → weight loss.
- Calorie surplus → weight gain.
Why it matters
Mifflin-St Jeor is now one of the most widely used and accurate formulas for estimating basal metabolic rate in the general population, particularly in overweight and obesity — which is why it is often preferred in clinical and nutritional practice.
Compare the result with Harris-Benedict and FAO/WHO, or see the guide to basal metabolic rate formulas.
What to enter
- Current weight in kg.
- Height in cm.
- Age in years and sex.
The formula uses total body weight: with a high fat mass the requirement may be slightly overestimated.
What to do about your result
Use the requirement as a starting point and adjust it while tracking your weight over time.
When to see a professional: for strongly hypocaloric diets, medical conditions or major weight goals, work with a doctor or dietitian.
Limitations of the formula
- It is an estimate: it does not directly measure energy expenditure.
- It ignores body composition: it can underestimate needs in very muscular athletes.
- It is validated in adults; children need dedicated equations.