What Is the Mifflin-St Jeor Calculator?
The Mifflin-St Jeor calculator estimates your Basal Metabolic Rate (BMR) — the calories your body burns at rest — and your total daily energy expenditure (TDEE) when activity is added. The Mifflin-St Jeor equation, published in 1990, is widely regarded as the most accurate predictive equation for most people, which is why dietitians and fitness professionals favor it. Enter your stats and the calculator returns your BMR and daily calorie needs.
How to Use the Calculator
- Enter weight, height, and age.
- Select your sex (the equation differs slightly).
- Choose your activity level.
- Calculate — see your BMR and maintenance calories.
The Mifflin-St Jeor Equation
Using metric units (kg, cm, years):
Men: BMR = 10 × weight + 6.25 × height − 5 × age + 5
Women: BMR = 10 × weight + 6.25 × height − 5 × age − 161
BMR is then multiplied by an activity factor to estimate total daily calories (TDEE).
Activity Multipliers
| Activity Level | Multiplier |
|---|---|
| Sedentary (little exercise) | 1.2 |
| Lightly active (1–3 days/week) | 1.375 |
| Moderately active (3–5 days/week) | 1.55 |
| Very active (6–7 days/week) | 1.725 |
| Extra active (physical job/training) | 1.9 |
Using Your Results
- Maintenance: eat around your TDEE to maintain weight.
- Weight loss: a moderate deficit (e.g., 500 calories/day) for steady loss.
- Weight gain: a moderate surplus to build muscle with training.
Frequently Asked Questions
What is the Mifflin-St Jeor equation?
It is a formula for estimating BMR from weight, height, age, and sex. It is considered one of the most accurate predictive equations for the general population.
What is BMR?
Basal Metabolic Rate is the number of calories your body burns at complete rest to maintain basic functions like breathing and circulation.
How is TDEE different from BMR?
BMR is your resting calorie burn, while TDEE (total daily energy expenditure) multiplies BMR by an activity factor to include movement and exercise.
Why is Mifflin-St Jeor preferred over Harris-Benedict?
Studies have found Mifflin-St Jeor to be more accurate for most modern populations than the older Harris-Benedict equation, which is why it is widely recommended.
Is this Mifflin-St Jeor calculator free?
Yes — it is completely free, requires no signup, and gives BMR and daily calorie needs.