BMR Calculator
Calculate your Basal Metabolic Rate (BMR), the number of calories your body burns at rest. Use the Mifflin-St Jeor and Harris-Benedict formulas to understand your daily calorie needs for weight management, fitness, and nutrition planning.
What Is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to maintain essential life-sustaining functions — breathing, circulation, cell production, and temperature regulation. It accounts for approximately 60-75% of your total daily energy expenditure.
Knowing your BMR helps you understand your baseline calorie needs. Combined with your activity level, it allows you to calculate your Total Daily Energy Expenditure (TDEE) — the total calories you burn each day. This is essential for weight management, whether you're looking to lose, gain, or maintain weight.
How Does the BMR Calculator Work?
This calculator uses two of the most validated formulas:
Mifflin-St Jeor (1990) — Recommended by the Academy of Nutrition and Dietetics as the most accurate for most people:
Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
Harris-Benedict (Revised 1984) — Historically the most widely used:
Men: BMR = 88.362 + (13.397 × weight [kg]) + (4.799 × height [cm]) − (5.677 × age [years])
Women: BMR = 447.593 + (9.247 × weight [kg]) + (3.098 × height [cm]) − (4.330 × age [years])
After calculating your BMR, the calculator multiplies it by your selected activity factor to estimate your Total Daily Energy Expenditure (TDEE) — the calories you burn including physical activity.
Why Use This BMR Calculator?
- Two Formulas: Compare Mifflin-St Jeor and Harris-Benedict results.
- Unit Flexibility: Switch between metric and imperial units.
- TDEE Estimation: Includes activity levels to calculate total daily calorie needs.
- Visual Breakdown: A chart shows the relationship between BMR and TDEE.
- Free & Private: No registration, no data storage.
Understanding Your Results
- BMR: The calories your body burns at complete rest. This is the minimum calories needed to sustain life.
- TDEE: Total Daily Energy Expenditure — your BMR multiplied by your activity level. This is the total calories you burn per day.
- Daily Calories: The estimated calories you need to consume to maintain your current weight.
- Activity Levels: Sedentary (1.2), Lightly Active (1.375), Moderately Active (1.55), Very Active (1.725), Extra Active (1.9).
❓ BMR Calculator FAQ
What is BMR?
BMR (Basal Metabolic Rate) is the number of calories your body burns at rest to maintain vital functions like breathing, circulation, and cell production. It accounts for 60-75% of your daily calorie burn.
What is the difference between BMR and TDEE?
BMR is the calories burned at complete rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by your activity level — it represents your total daily calorie burn including all physical activity.
Which BMR formula is the most accurate?
The Mifflin-St Jeor equation is considered the most accurate for most people and is recommended by the Academy of Nutrition and Dietetics. The Harris-Benedict formula is also widely used but is slightly older.
How do I calculate my BMR?
Enter your age, gender, height, and weight into the calculator. It will automatically compute your BMR using the Mifflin-St Jeor and Harris-Benedict formulas. The Mifflin-St Jeor formula is: Men: BMR = 10W + 6.25H - 5A + 5; Women: BMR = 10W + 6.25H - 5A - 161.
How do I use BMR for weight loss?
To lose weight, you need to consume fewer calories than your TDEE. A deficit of 500-1000 calories per day typically results in 0.5-1 kg (1-2 lbs) of weight loss per week. Calculate your TDEE using this calculator and subtract 500-1000 for a weight loss target.
How do I use BMR for weight gain?
To gain weight, consume more calories than your TDEE. A surplus of 300-500 calories per day typically results in 0.25-0.5 kg (0.5-1 lb) of weight gain per week. Calculate your TDEE and add 300-500 for a weight gain target.
What factors affect BMR?
BMR is influenced by age (decreases with age), gender (men generally have higher BMR), weight (more mass = higher BMR), height (taller = higher BMR), muscle mass (more muscle = higher BMR), and genetics.
How accurate is this BMR calculator?
This calculator uses validated formulas and provides estimates. Individual BMR can vary based on genetics, muscle mass, and other factors. For precise measurements, consider indirect calorimetry performed by a healthcare professional.
What is the Harris-Benedict formula?
The Harris-Benedict formula was developed in 1919 and revised in 1984. It uses age, gender, height, and weight to estimate BMR. The revised formula is: Men: 88.362 + (13.397 × weight[kg]) + (4.799 × height[cm]) - (5.677 × age); Women: 447.593 + (9.247 × weight[kg]) + (3.098 × height[cm]) - (4.330 × age).
What is the Mifflin-St Jeor formula?
The Mifflin-St Jeor formula was developed in 1990 and is considered the most accurate for estimating BMR. It is: Men: BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age (years) + 5; Women: BMR = 10 × weight (kg) + 6.25 × height (cm) - 5 × age (years) - 161.
What is TDEE?
TDEE (Total Daily Energy Expenditure) is the total number of calories you burn in a day, including all physical activity. It is calculated by multiplying your BMR by an activity factor that reflects your lifestyle.
What are the activity levels in TDEE?
Activity levels: Sedentary (1.2) — little to no exercise; Lightly Active (1.375) — 1-3 days/week; Moderately Active (1.55) — 3-5 days/week; Very Active (1.725) — 6-7 days/week; Extra Active (1.9) — athlete or physical job.
Can I use this calculator for bodybuilding?
Yes. Bodybuilders can use BMR and TDEE to plan bulking (calorie surplus) and cutting (calorie deficit) phases. For more precise results, consider using the Katch-McArdle formula which uses body fat percentage, but that's not included in this calculator.
How often should I recalculate my BMR?
Recalculate your BMR whenever your weight changes significantly (2-3 kg / 5-10 lbs), your activity level changes, or every few months as you age. BMR decreases slightly with age.
What is the difference between BMR and RMR?
BMR (Basal Metabolic Rate) is measured under strict conditions: complete rest, fasting, and in a thermoneutral environment. RMR (Resting Metabolic Rate) is measured under less strict conditions and is slightly higher than BMR. They are often used interchangeably.
How do I convert between metric and imperial units?
Select the unit system at the top of the calculator. For imperial: height in inches and weight in pounds. The calculator will automatically convert to the metric formulas. 1 inch = 2.54 cm, 1 lb = 0.453592 kg.
Is this calculator suitable for children or adolescents?
These formulas are designed for adults (18+ years). Children and adolescents have different metabolic needs and should consult a healthcare professional for accurate calorie guidance.
What is the Katch-McArdle formula?
The Katch-McArdle formula uses lean body mass instead of total weight and is considered more accurate when body fat percentage is known. It is: BMR = 370 + (21.6 × Lean Body Mass [kg]). This calculator does not include this formula.
How does muscle mass affect BMR?
Muscle tissue burns more calories at rest than fat tissue. Increasing muscle mass through strength training can increase your BMR, helping you burn more calories even when not exercising.