BMR Calculator (Metric: kg & cm)
Enter your details below to estimate your Basal Metabolic Rate (BMR) and your daily calories based on activity level.
Formula used: Mifflin-St Jeor Equation (metric version).
What is basal metabolic rate (BMR)?
Basal Metabolic Rate is the number of calories your body needs to perform essential life functions while at complete rest. This includes breathing, circulation, temperature regulation, hormone production, and basic cellular repair. In simple terms, BMR is your baseline energy requirement before workouts, walking, or daily activities are added.
If you want to lose fat, gain muscle, or maintain your weight, knowing your BMR is a practical starting point. It helps you avoid guessing and gives you a more informed target for daily calorie intake.
Why use a BMR calculator in kg?
Many formulas in nutrition and fitness are designed for metric inputs. Using kilograms and centimeters reduces conversion errors and keeps calculations straightforward. This calculator is built specifically for metric users, so you can enter:
- Weight in kilograms (kg)
- Height in centimeters (cm)
- Age in years
- Sex and activity level
Formula used in this calculator
Mifflin-St Jeor Equation
The calculator uses the Mifflin-St Jeor formula, one of the most widely accepted equations for estimating BMR in healthy adults.
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
After BMR is estimated, total daily energy expenditure (TDEE) is calculated by multiplying BMR by your selected activity factor. TDEE is the approximate number of calories needed to maintain your current body weight.
How to use your result
1) Maintenance
Use your TDEE as a baseline to maintain body weight over time.
2) Fat loss
A moderate calorie deficit of around 10-20% below TDEE is commonly used. This often supports sustainable fat loss while preserving energy and muscle.
3) Muscle gain
A controlled surplus of about 5-15% above TDEE is often used for lean mass gain. Pair this with progressive resistance training and adequate protein intake.
Example (metric)
Suppose a 30-year-old male weighs 70 kg and is 175 cm tall:
- BMR = (10×70) + (6.25×175) − (5×30) + 5
- BMR = 700 + 1093.75 − 150 + 5 = 1648.75 kcal/day
If he is moderately active (factor 1.55), estimated maintenance calories: 1648.75 × 1.55 ≈ 2556 kcal/day.
What affects BMR?
- Body composition: More lean mass usually means higher BMR.
- Age: BMR often decreases gradually with age.
- Sex: Average differences in lean mass can influence BMR.
- Genetics: Individual metabolic variation is real.
- Hormones and health status: Thyroid function, illness, and medications may change energy needs.
- Dieting history: Prolonged aggressive deficits can reduce energy expenditure over time.
BMR vs RMR vs TDEE
- BMR: Calories needed at complete physiological rest.
- RMR: Resting Metabolic Rate; similar but measured under less strict lab conditions.
- TDEE: Total calories burned in a day, including activity and exercise.
For practical nutrition planning, BMR gives a strong baseline and TDEE gives a day-to-day target.
Tips for a healthy metabolism
- Prioritize resistance training to preserve or build lean mass.
- Eat enough protein (often 1.6-2.2 g/kg/day for active adults).
- Sleep 7-9 hours consistently.
- Manage stress and recovery to support hormonal balance.
- Avoid overly aggressive crash diets for long periods.
FAQ
Is this 100% accurate?
No. It is an estimate, not a lab test. Use it as a starting point, then adjust based on 2-4 weeks of real progress data.
Can I use this if I am trying to lose weight?
Yes. Calculate TDEE first, then reduce calories moderately and track trends in weight, measurements, and performance.
Should I recalculate BMR?
Yes. Recalculate whenever weight, training volume, or routine changes significantly.
Note: This tool is for educational purposes and does not replace medical advice. If you have a medical condition, consult a qualified healthcare professional.