What is the Mifflin-St Jeor equation?

The Mifflin-St Jeor equation estimates Basal Metabolic Rate (BMR). For men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161 + 166. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age - 161.

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor and represents the total calories you burn in a day.

How many calories should I eat to lose weight?

A safe calorie deficit for weight loss is 500 calories below your TDEE, which translates to approximately 1 pound (0.45 kg) of weight loss per week. Consult a healthcare provider before starting any weight loss plan.

How accurate is a calorie calculator?

Calorie calculators provide estimates based on population averages. Individual metabolism can vary by 10-15%. Use the results as a starting point and adjust based on actual results over 2-4 weeks.

How many calories do I need to gain muscle?

To gain muscle, you generally need a surplus of 250-500 calories above your TDEE combined with resistance training and adequate protein (1.6-2.2g per kg body weight).

Should I eat back the calories I burn during exercise?

If your TDEE already accounts for your activity level, you generally do not need to eat back exercise calories separately. Be cautious with fitness tracker estimates, as they tend to overestimate by 30-40%.

Why is my metabolism slow even though I exercise?

Factors beyond exercise affect metabolism: age, hormonal imbalances, prolonged caloric restriction, insufficient sleep, and medications. If you suspect a metabolic issue, consult an endocrinologist.

What is the minimum number of calories I should eat per day?

Health experts recommend not going below 1,200 calories/day for women or 1,500 for men without medical supervision. Very low-calorie diets should only be followed under medical guidance.

Calorie Calculator

Estimate your daily calorie needs using the Mifflin-St Jeor equation. Get your BMR and TDEE for maintenance, weight loss, and weight gain.

Age (years)

Gender

Height (cm)

Weight (kg)

Activity Level

How to Use the Calorie Calculator

Estimating your daily calorie needs is straightforward:

Enter your age — Your age in years affects your metabolic rate.
Select your gender — Men and women have different BMR calculations.
Enter your height and weight — Use centimeters and kilograms for accurate results.
Select your activity level — Choose the option that best describes your typical weekly physical activity.
Click "Calculate Calories" — View your BMR, maintenance calories (TDEE), and recommended intake for weight loss or gain.

About Calorie Calculation

This calculator uses the Mifflin-St Jeor equation, which is widely considered the most accurate formula for estimating Basal Metabolic Rate (BMR). Published in 1990, it has been validated in numerous studies and is recommended by the Academy of Nutrition and Dietetics.

The Mifflin-St Jeor formulas are:

Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161

Your BMR is then multiplied by an activity factor to determine your Total Daily Energy Expenditure (TDEE). For weight loss, a deficit of 500 calories per day (approximately 1 pound per week) is generally recommended. For weight gain, a surplus of 500 calories per day is typical. Always consult a healthcare professional before making significant changes to your diet.

Calorie Calculation Examples

Here are step-by-step examples showing how daily calorie needs are calculated for different people:

30-year-old male, 180 cm, 80 kg, moderately active: BMR = (10 × 80) + (6.25 × 180) - (5 × 30) + 5 = 800 + 1,125 - 150 + 5 = 1,780 cal/day. TDEE = 1,780 × 1.55 = 2,759 cal/day. Weight loss target: 2,259 cal/day.
25-year-old female, 165 cm, 60 kg, lightly active: BMR = (10 × 60) + (6.25 × 165) - (5 × 25) - 161 = 600 + 1,031 - 125 - 161 = 1,345 cal/day. TDEE = 1,345 × 1.375 = 1,849 cal/day.
45-year-old male, 175 cm, 90 kg, sedentary: BMR = (10 × 90) + (6.25 × 175) - (5 × 45) + 5 = 900 + 1,094 - 225 + 5 = 1,774 cal/day. TDEE = 1,774 × 1.2 = 2,129 cal/day. This person needs to eat below 2,129 calories to lose weight.
22-year-old female, 170 cm, 65 kg, very active (athlete): BMR = (10 × 65) + (6.25 × 170) - (5 × 22) - 161 = 650 + 1,063 - 110 - 161 = 1,442 cal/day. TDEE = 1,442 × 1.725 = 2,487 cal/day. Weight gain target: 2,987 cal/day.
35-year-old male, 178 cm, 75 kg, wants to gain muscle: BMR = (10 × 75) + (6.25 × 178) - (5 × 35) + 5 = 750 + 1,113 - 175 + 5 = 1,693 cal/day. TDEE = 1,693 × 1.55 = 2,624 cal/day. Bulk target with surplus: 3,124 cal/day.

Quick Reference: Activity Level Multipliers

The activity factor multiplied by your BMR determines your Total Daily Energy Expenditure (TDEE). Use this table to choose the right level.

Activity Level	Factor	Description	Example TDEE (BMR 1,700)
Sedentary	1.2	Desk job, little or no exercise	2,040 cal
Lightly Active	1.375	Light exercise 1-3 days/week	2,338 cal
Moderately Active	1.55	Moderate exercise 3-5 days/week	2,635 cal
Very Active	1.725	Hard exercise 6-7 days/week	2,933 cal
Extra Active	1.9	Very hard exercise or physical job	3,230 cal

Frequently Asked Questions

The Mifflin-St Jeor equation is a formula used to estimate Basal Metabolic Rate (BMR). For men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161. It is considered one of the most accurate BMR estimation formulas available.

BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest to maintain basic functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) includes your BMR plus calories burned through daily activities and exercise. TDEE = BMR × Activity Factor.

A safe and sustainable rate of weight loss is about 1 pound (0.45 kg) per week, which requires a daily deficit of approximately 500 calories below your TDEE. Eating below your BMR is generally not recommended. Always consult with a healthcare provider before beginning a weight loss program.

The Mifflin-St Jeor equation is accurate to within about 10% for most people. Individual factors like genetics, body composition, medications, and health conditions can affect actual calorie needs. Use the results as a starting point and adjust based on your real-world results over 2 to 4 weeks.

To gain muscle, you generally need a caloric surplus of 250-500 calories above your TDEE, combined with a resistance training program and adequate protein intake (1.6-2.2g per kg of body weight). A 250-calorie surplus minimizes fat gain while supporting muscle growth (lean bulk), while a 500-calorie surplus leads to faster muscle gain but with more fat accumulation.

If your TDEE already accounts for your activity level, you generally do not need to eat back exercise calories separately, as they are already factored in. However, if you do unusually intense exercise beyond your normal routine, you may need additional fuel. Be cautious with fitness tracker calorie burn estimates, as they tend to overestimate by 30-40%.

Several factors can affect metabolic rate beyond exercise: age (metabolism decreases about 1-2% per decade after 20), hormonal imbalances (thyroid, cortisol), prolonged caloric restriction (adaptive thermogenesis), insufficient sleep, and medications. If you suspect a metabolic issue despite regular exercise, consult an endocrinologist for proper testing.

Health experts generally recommend not going below 1,200 calories per day for women or 1,500 calories per day for men without medical supervision. Eating too few calories can lead to nutrient deficiencies, muscle loss, metabolic slowdown, and other health problems. Very low-calorie diets should only be followed under medical guidance.