Basal Metabolic Rate - 3 Accurate Formulas
✓ 3 BMR Formulas - Mifflin, Harris-Benedict, Katch-McArdle
✓ Metabolic Age - Know your biological metabolism age
✓ Organ Breakdown - See where calories burn
✓ Age Comparison - Track metabolism changes
Your BMR
1643
calories/day at rest
🧬 Metabolic Age
25
years
Perfect match with your actual age
Daily Calories (TDEE)
2546
📊 vs Average Person:
0%
Average male: 1643 cal/day
🫁
Liver
443
27% of BMR
🧠
Brain
312
19% of BMR
❤️
Heart
115
7% of BMR
🫘
Kidneys
115
7% of BMR
💪
Muscles
296
18% of BMR
🔬
Other
361
22% of BMR
Pizza Slice
285 cal
4.2h
to burn at rest
Big Mac
563 cal
8.2h
to burn at rest
Chocolate Bar
235 cal
3.4h
to burn at rest
Banana
105 cal
1.5h
to burn at rest
Apple
95 cal
1.4h
to burn at rest
💡 With activity, burning time decreases significantly!
| Age | BMR (cal/day) | Difference |
|---|---|---|
| 20 years | 1668 | -25 cal |
| 30 years | 1618 | +25 cal |
| 40 years | 1568 | +75 cal |
| 50 years | 1518 | +125 cal |
| 60 years | 1468 | +175 cal |
💡 Metabolism typically decreases 2-3% per decade after age 30
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain vital functions like breathing, circulation, cell production, and nutrient processing. It represents the minimum energy needed to keep you alive.
Our calculator uses 3 scientifically-proven formulas: Mifflin-St Jeor (98% accurate, 2025 standard), Harris-Benedict Revised (95% accurate), and Katch-McArdle (99% accurate for athletes with body composition data).
Most accurate for general population (Est. 1990)
Men:
10×W + 6.25×H - 5×A + 5
Women:
10×W + 6.25×H - 5×A - 161
W=weight(kg), H=height(cm), A=age
Classic formula, revised (Est. 1984)
Men:
88.4 + 13.4×W + 4.8×H - 5.68×A
Women:
447.6 + 9.25×W + 3.1×H - 4.33×A
Good for tracking long-term trends
Best for athletes (Est. 1975)
Formula:
370 + 21.6 × LBM
LBM = Lean Body Mass (kg)
LBM = W × (1 - BF%/100)
Requires body fat percentage
Calories burned at complete rest - sleeping, lying down, zero activity.
• Resting energy expenditure
• Vital functions only (breathing, heartbeat)
• Does NOT include activity
• Lower than TDEE
Total calories burned including all daily activities and exercise.
• BMR + Activity calories
• Formula: TDEE = BMR × Activity Factor
• Includes exercise, walking, work
• Your maintenance calories
💡 Example:
BMR = 1,500 cal/day • Activity Factor = 1.55 (Moderately Active) • TDEE = 1,500 × 1.55 = 2,325 cal/day
BMR decreases 2-3% per decade after age 30. Metabolism slows as muscle mass naturally declines.
Men typically have 5-10% higher BMR due to greater muscle mass and testosterone levels.
Muscle tissue burns more calories than fat. More muscle = higher BMR.
Metabolic rate varies 20-30% between individuals due to genetic factors and family history.
Thyroid, insulin, cortisol affect metabolism. Thyroid disorders can change BMR by 15-40%.
Severe calorie restriction lowers BMR. Protein-rich diets can slightly increase it (thermic effect).
Strength Training
+50-100 cal/dayBuild muscle mass (muscle burns 3x more than fat)
HIIT Workouts
+200-400 cal/dayHigh-intensity interval training boosts metabolism for 24-48 hours
Protein-Rich Diet
+100-150 cal/dayProtein has 20-30% thermic effect (digestion burns calories)
Stay Hydrated
+30-50 cal/dayCold water intake temporarily boosts metabolism
Quality Sleep
+50-100 cal/day7-8 hours maintains hormonal balance (leptin, ghrelin)
Crash Dieting
-200-400 cal/daySevere calorie restriction triggers adaptive thermogenesis
Sedentary Lifestyle
-100-200 cal/dayLack of movement reduces muscle mass
Poor Sleep
-50-100 cal/dayLess than 6 hours disrupts metabolic hormones
Stress & Cortisol
-50-150 cal/dayChronic stress slows metabolism, increases fat storage
Skipping Meals
-30-80 cal/dayIrregular eating confuses metabolism
The Mifflin-St Jeor equation is considered the most accurate for the general population (98% accuracy). It was developed in 1990 and is now the standard used by nutritionists and healthcare professionals.
✅ Use Mifflin-St Jeor if:
✅ Use Katch-McArdle if:
✅ Use Harris-Benedict if:
Your BMR tells you the minimum calories needed. For weight management, calculate your TDEE (BMR × Activity Factor), then adjust:
🔻 For Weight Loss:
Mild deficit: TDEE - 250 cal = 0.25 kg loss/week
Moderate deficit: TDEE - 500 cal = 0.5 kg loss/week
Aggressive deficit: TDEE - 750-1000 cal = 0.75-1 kg loss/week
⚠️ Never eat below your BMR for extended periods!
🔺 For Weight Gain:
Lean bulk: TDEE + 250 cal = 0.25 kg gain/week
Standard bulk: TDEE + 500 cal = 0.5 kg gain/week
💡 Combine with strength training for muscle gain
Metabolic age compares your BMR to average BMR of different age groups. If your BMR is higher than average for your age, your metabolic age is younger (good!). If lower, it's older (needs improvement).
How it's calculated:
Your BMR is compared to the average BMR curve across different ages. The age that matches your BMR is your metabolic age.
Metabolic Age < Actual
Excellent metabolism!
Metabolic Age = Actual
Normal metabolism
Metabolic Age > Actual
Needs improvement
Example: You're 30 years old but your BMR matches the average 25-year-old. Your metabolic age = 25 years! 🎉