BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to keep you alive (breathing, heartbeat, organ function). A 70kg, 170cm, 30-year-old male has a BMR of approximately 1,695 calories. Even sleeping, you burn this many calories. Your actual daily need is BMR x Activity Level.
📂 Health
🔥 BMR Calculator
Calculate your Basal Metabolic Rate — the calories your body burns at rest. Essential for weight management, diet planning, and understanding your metabolism. Accurate Mifflin-St Jeor formula.
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✅ Trusted Tool
The 365tool.net BMR Calculator uses the Mifflin-St Jeor formula recommended by the Academy of Nutrition and Dietetics. Free for everyone managing their health and weight. Consult a dietitian for personalised nutrition advice.
🤔 How Does This Work?
Our BMR Calculator uses three well-established formulas:
Mifflin-St Jeor: Male: (10 x kg) + (6.25 x cm) - (5 x age) + 5. Female: (10 x kg) + (6.25 x cm) - (5 x age) - 161
Harris-Benedict: Male: 88.362 + (13.397 x kg) + (4.799 x cm) - (5.677 x age). Female: 447.593 + (9.247 x kg) + (3.098 x cm) - (4.330 x age)
Katch-McArdle: 370 + (21.6 x Lean Body Mass). Lean mass = weight x (1 - body fat %/100)
❓ Frequently Asked Questions
What is BMR and why does it matter?▼
BMR is the minimum calories your body needs to function at rest — breathing, blood circulation, cell repair, temperature regulation. It matters because it is the foundation of all calorie calculations. Your actual needs are BMR x activity multiplier.
What is the most accurate BMR formula?▼
The Mifflin-St Jeor formula (1990) is the most accurate for most people. Studies show it is accurate within 10% for 82% of people. The Harris-Benedict formula (1919) is older and slightly less accurate. If you know your body fat %, Katch-McArdle is most precise.
What is the difference between BMR and TDEE?▼
BMR = calories at absolute rest. TDEE (Total Daily Energy Expenditure) = BMR x Activity Factor. If your BMR is 1,500 and you exercise moderately, your TDEE might be 1,500 x 1.55 = 2,325 calories/day. Eat below TDEE to lose weight.
Does muscle affect BMR?▼
Yes! Muscle tissue burns about 3x more calories than fat tissue even at rest. People with more muscle mass have higher BMR and burn more calories even while sleeping. This is why strength training supports long-term weight management.
How does age affect BMR?▼
BMR decreases by about 1-2% per decade after age 20. A 40-year-old has roughly 5-8% lower BMR than they did at 20 with the same weight and height. This is partly why people gain weight as they age without changing eating habits.
BMR is the minimum calories your body needs to function at rest — breathing, blood circulation, cell repair, temperature regulation. It matters because it is the foundation of all calorie calculations. Your actual needs are BMR x activity multiplier.
What is the most accurate BMR formula?▼
The Mifflin-St Jeor formula (1990) is the most accurate for most people. Studies show it is accurate within 10% for 82% of people. The Harris-Benedict formula (1919) is older and slightly less accurate. If you know your body fat %, Katch-McArdle is most precise.
What is the difference between BMR and TDEE?▼
BMR = calories at absolute rest. TDEE (Total Daily Energy Expenditure) = BMR x Activity Factor. If your BMR is 1,500 and you exercise moderately, your TDEE might be 1,500 x 1.55 = 2,325 calories/day. Eat below TDEE to lose weight.
Does muscle affect BMR?▼
Yes! Muscle tissue burns about 3x more calories than fat tissue even at rest. People with more muscle mass have higher BMR and burn more calories even while sleeping. This is why strength training supports long-term weight management.
How does age affect BMR?▼
BMR decreases by about 1-2% per decade after age 20. A 40-year-old has roughly 5-8% lower BMR than they did at 20 with the same weight and height. This is partly why people gain weight as they age without changing eating habits.