BMR Calculator
Calculate your Basal Metabolic Rate using Mifflin-St Jeor and Harris-Benedict formulas. See daily calorie needs by activity level.
Enter your details and click Calculate.
How Does the Formula Work?
The Basal Metabolic Rate (BMR) is the number of calories your body requires at complete rest to maintain basic life-sustaining functions — breathing, blood circulation, brain activity, cell repair, and temperature regulation. BMR accounts for 60–75% of total daily energy expenditure in most people, making it the largest component of your calorie budget.
Male: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − (−5)
Female: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Harris-Benedict Revised (1984):
Male: BMR = 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age
Female: BMR = 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age
TDEE = BMR × Activity Factor
Sedentary: ×1.2 | Light: ×1.375 | Moderate: ×1.55
Active: ×1.725 | Very Active: ×1.9
Mifflin-St Jeor vs Harris-Benedict
The Mifflin-St Jeor equation was published in 1990 and is considered the most accurate BMR formula for the general population. The American Dietetic Association recommends it as the gold standard for estimating resting energy expenditure. The Harris-Benedict equation dates to 1919 (revised in 1984) and tends to overestimate BMR by 5–15%, particularly in overweight individuals. This calculator shows both so you can compare, but the TDEE calculations use Mifflin-St Jeor for better accuracy.
Understanding TDEE
Total Daily Energy Expenditure (TDEE) adds your physical activity to BMR. Most people fall in the sedentary to moderate range. If you have a desk job and exercise 3 times a week, "moderate" is typically appropriate. TDEE is the number that matters for weight management: eating below your TDEE creates a caloric deficit (weight loss), eating above creates a surplus (weight gain), and eating at your TDEE maintains your current weight. A deficit of approximately 500 kcal/day below TDEE typically results in about 0.5 kg of weight loss per week.
Factors That Affect BMR
Several factors influence your BMR beyond weight, height, age, and gender. Muscle mass raises BMR because muscle tissue is more metabolically active than fat tissue — this is why strength training can increase your resting calorie burn. Hormonal factors like thyroid function significantly affect metabolic rate. Genetics play a role, with natural variation of 5–10% between individuals of similar size. Extreme dieting can temporarily lower BMR as the body adapts to reduced calorie intake, a phenomenon called metabolic adaptation.
Important Considerations
BMR calculators provide estimates, not exact measurements. The gold standard for measuring actual metabolic rate is indirect calorimetry, performed in a clinical setting. These formulas do not account for body composition — a muscular person and an equally heavy person with more body fat will have different actual BMRs even if the formulas give similar numbers. For personalized nutrition planning, especially for medical conditions, weight management programs, or athletic performance, consult a registered dietitian or healthcare provider.
Tips & Recommendations
Mifflin-St Jeor is recommended by the American Dietetic Association. Harris-Benedict is the classic formula. Compare both for a range estimate.
Eat below TDEE to lose weight, at TDEE to maintain, above TDEE to gain. A 500 kcal/day deficit ≈ 0.5 kg/week loss.
Most people overestimate their activity level. If unsure, choose one level lower. A desk job + 3 gym sessions = "moderate" at most.
BMR is your body's minimum energy need. Eating below BMR without medical supervision can harm your health and slow metabolism.
Frequently Asked Questions
What is BMR?
Basal Metabolic Rate is the number of calories your body burns at complete rest to maintain vital functions like breathing, circulation, and cell production. It represents the minimum energy your body needs to survive.
What is the difference between Mifflin-St Jeor and Harris-Benedict?
Both estimate BMR from weight, height, age, and gender. Mifflin-St Jeor (1990) is considered more accurate for modern populations and is recommended by the American Dietetic Association. Harris-Benedict (1984 revision) is the classic formula still widely used.
What is TDEE?
Total Daily Energy Expenditure is your BMR multiplied by an activity factor. It estimates how many calories you actually burn per day including exercise and daily movement.
Which activity level should I choose?
Sedentary: desk job, no exercise. Light: 1–3 workouts/week. Moderate: 3–5 workouts/week. Active: 6–7 intense workouts/week. Very Active: intense daily training plus a physical job.
Can I use BMR for weight loss?
TDEE is more useful for weight management. A deficit of 500 kcal/day below your TDEE typically results in about 0.5 kg (1 lb) weight loss per week. Never eat below your BMR without medical supervision.
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