BMR Calculator
Calculate your Basal Metabolic Rate (BMR) — the calories your body burns at complete rest — using the Mifflin-St Jeor and Harris-Benedict equations.
Calculate Basal Metabolic Rate (BMR = 10W + 6.25H − 5A + 5)
Enter your body measurements below to compute verified resting energy expenditure.
Calculation Results
Calculated using verified physical methodology: \text{BMR (Male)} = 10W + 6.25H - 5A + 5 \quad \text{(Mifflin-St Jeor 1990)}
\text{BMR (Female)} = 10W + 6.25H - 5A - 161
Quick Summary
The BMR Calculator evaluates Basal Metabolic Rate ($\text{BMR}_{\text{Male}} = 10W + 6.25H - 5A + 5$) using the Mifflin-St Jeor equation — the most accurate validated formula for estimating resting energy expenditure in adults.
Formula Explanation
\text{BMR (Male)} = 10W_{kg} + 6.25H_{cm} - 5A_{years} + 5
\text{BMR (Female)} = 10W_{kg} + 6.25H_{cm} - 5A_{years} - 161
\text{where } W = \text{weight (kg), } H = \text{height (cm), } A = \text{age (years)}How It Works
The BMR Calculator applies the Mifflin-St Jeor equation, multiplying body weight (kg) by 10, height (cm) by 6.25, and age (years) by 5, then adding 5 (men) or subtracting 161 (women) to compute resting energy expenditure in kcal/day. It also computes per-hour and per-minute burn rates at complete rest, and minimum safe calorie intake (70% of BMR).
Step-by-Step Worked Example
Practical Problem: Male, 30 years old, 75 kg, 175 cm tall. Calculate BMR using Mifflin-St Jeor.
- Step 1: Weight term: $10 \times 75 = 750$.
- Step 2: Height term: $6.25 \times 175 = 1093.75$.
- Step 3: Age term: $5 \times 30 = 150$.
- Step 4: BMR (Male): $750 + 1093.75 - 150 + 5 = \mathbf{1698.75\text{ kcal/day}}$.
- Step 5: Hourly rate: $1698.75 / 24 = \mathbf{70.8\text{ kcal/hour}}$ at complete rest.
Real-World Calculation Examples
Scenario 1: Male, 30y, 75 kg, 175 cm
Result: BMR = 1,699 kcal/day (Mifflin-St Jeor). 70.8 kcal/hr at rest.
Scenario 2: Female, 25y, 60 kg, 165 cm
Result: BMR = 1,356 kcal/day (Mifflin-St Jeor). 56.5 kcal/hr at rest.
Scenario 3: Male, 50y, 90 kg, 180 cm
Result: BMR = 1,905 kcal/day (Mifflin-St Jeor). 79.4 kcal/hr at rest.
Scenario 4: Female, 45y, 70 kg, 170 cm
Result: BMR = 1,470 kcal/day (Mifflin-St Jeor). 61.3 kcal/hr at rest.
Key Benefits of Using This Calculator
Dual Formula Comparison
Computes BMR using both Mifflin-St Jeor and Harris-Benedict (revised) equations for comparison.
Hourly & Per-Minute Burn Rate
Outputs BMR per hour and per minute at complete rest for granular calorie tracking.
Minimum Safe Intake Warning
Flags 70% of BMR as the minimum safe daily calorie intake to prevent metabolic adaptation.
100% Free & Client-Side
Executes locally in your browser with zero latency or web server transmission.
Frequently Asked Questions (FAQ)
What is BMR?
BMR (Basal Metabolic Rate) is the number of calories the body burns per day to maintain essential functions (breathing, circulation, cell repair) at complete rest.
What is the difference between BMR and RMR?
BMR is measured in a strict clinical post-absorptive state. RMR (Resting Metabolic Rate) is slightly higher (~10-20 kcal/day) and is the typical "at rest" value most calculators estimate.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation (1990) is consistently validated as the most accurate for non-athletic adults. The Katch-McArdle equation is superior for athletes with known lean body mass.
Can I eat below my BMR to lose weight?
Eating significantly below BMR triggers metabolic adaptation, muscle loss, and hormonal suppression. Minimum safe intake is approximately 70-80% of BMR.
Does BMR change with exercise?
Resistance training increases muscle mass, which raises BMR long-term. Each kg of additional muscle mass raises BMR by approximately 13-50 kcal/day.
Why is BMR lower in women than men?
Women typically have a lower muscle-to-fat ratio and lower testosterone levels, resulting in BMR approximately 5-10% lower than men of the same weight and height.
Does BMR decrease with age?
Yes — BMR decreases approximately 1-2% per decade after age 20, largely due to sarcopenia (age-related muscle loss).
What contributes to total daily calorie burn?
BMR (60-70%) + Exercise Activity (15-30%) + NEAT/Non-exercise activity (10-15%) + Thermic Effect of Food/TEF (8-10%) = Total Daily Energy Expenditure (TDEE).
What is the average BMR for men and women?
Average male BMR (30-40y, 80 kg, 178 cm): ~1,900-2,000 kcal/day. Average female BMR (30-40y, 65 kg, 165 cm): ~1,400-1,500 kcal/day.
How does thyroid function affect BMR?
Hypothyroidism (underactive thyroid) can reduce BMR by 15-30%; hyperthyroidism (overactive thyroid) can increase BMR by 25-60% above normal values.