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BMR Calculator
Calculate your daily calorie needs at rest
What is BMR and Why Does It Matter?
Basal Metabolic Rate (BMR) represents the minimum amount of energy your body needs to perform essential functions while at complete rest. These functions include breathing, circulating blood, cell production, nutrient processing, and maintaining body temperature.
Your BMR accounts for approximately 60-70% of the calories you burn each day, making it the largest component of your total daily energy expenditure. Understanding your BMR is crucial for:
- Weight management: Knowing your BMR helps establish realistic calorie goals for weight loss or gain
- Nutritional planning: Ensures you're consuming enough calories to support basic bodily functions
- Metabolic health: Can help identify potential metabolic issues if significantly higher or lower than expected
How to Calculate BMR?
This calculator uses the Mifflin-St Jeor Equation, widely regarded as the most accurate formula for estimating BMR:
For men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
For women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161
Calculate Your BMR
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) - the number of calories your body needs at rest to maintain basic functions like breathing and circulation.
Understanding Your BMR Results
Your BMR is just the starting point for understanding your daily caloric needs. To determine your total daily energy expenditure (TDEE), you need to factor in your activity level:
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or no exercise, desk job | BMR × 1.2 |
| Lightly Active | Light exercise 1-3 days/week | BMR × 1.375 |
| Moderately Active | Moderate exercise 3-5 days/week | BMR × 1.55 |
| Very Active | Hard exercise 6-7 days/week | BMR × 1.725 |
| Extra Active | Very hard exercise & physical job or training twice a day | BMR × 1.9 |
Example:
If your calculated BMR is 1,500 calories and you're moderately active, your estimated daily calorie needs would be:
1,500 × 1.55 = 2,325 calories per day
Common BMR Questions Answered
What is the BMR for a 30-year-old man?
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) - the number of calories your body needs at rest to maintain basic functions like breathing and circulation.
How many calories does a 25-year-old woman burn at rest?
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) - the number of calories your body needs at rest to maintain basic functions like breathing and circulation.
What is a normal BMR for a 45-year-old man?
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) - the number of calories your body needs at rest to maintain basic functions like breathing and circulation.
BMR for a 35-year-old woman in imperial units?
BMR Calculator
Calculate your Basal Metabolic Rate (BMR) - the number of calories your body needs at rest to maintain basic functions like breathing and circulation.
What is a good BMR?
There's no single "good" BMR value as it varies significantly based on individual factors like age, gender, height, weight, and body composition. However, typical BMR ranges are:
| Gender | Age Range | Typical BMR Range (calories/day) |
|---|---|---|
| Women | 18-30 | 1,200 - 1,500 |
| 31-50 | 1,100 - 1,400 | |
| 51+ | 1,000 - 1,300 | |
| Men | 18-30 | 1,500 - 1,800 |
| 31-50 | 1,400 - 1,700 | |
| 51+ | 1,200 - 1,600 |
Note: These are general ranges. Individual BMR can vary based on genetics, muscle mass, and overall health status.
How many calories do I burn doing nothing?
Your BMR represents exactly that—the calories you burn "doing nothing." Even when completely at rest, your body is performing countless essential functions:
Basic Functions:
- Breathing
- Blood circulation
- Cell growth and repair
- Brain function
- Maintaining body temperature
Percentage of Daily Energy:
- BMR: 60-70% of daily calories
- Physical activity: 15-30% of daily calories
- Thermic effect of food: 10% of daily calories
So when you're sleeping or lying completely still, you're still burning a significant amount of calories—your BMR value represents this baseline calorie burn.
Factors That Affect Your BMR
Why is my BMR so low?
Several factors can contribute to a lower-than-expected BMR:
- Age: BMR naturally decreases by about 2% per decade after age 20
- Low muscle mass: Muscle burns more calories at rest than fat
- Severe calorie restriction: Prolonged dieting can slow metabolism
- Hormonal issues: Hypothyroidism and other hormonal imbalances
- Genetics: Some people naturally have a slower metabolism
If your BMR seems unusually low and you're experiencing symptoms like fatigue, weight gain, or cold intolerance, consider consulting with a healthcare provider to rule out medical conditions.
How to increase BMR naturally?
You can boost your metabolic rate through several evidence-based strategies:
- Build muscle: Strength training 2-3 times per week
- High-intensity interval training (HIIT): Creates an "afterburn" effect
- Eat sufficient protein: Has a higher thermic effect than carbs or fats
- Stay hydrated: Dehydration can slow metabolism
- Get adequate sleep: Sleep deprivation disrupts metabolic hormones
- Avoid severe calorie restriction: Eating too little can lower BMR
Remember that healthy metabolism changes happen gradually—there are no quick fixes for permanently increasing BMR.
BMR and Weight Management
How to use BMR for weight loss?
Your BMR forms the foundation of any effective weight loss plan. Here's how to use it:
- Calculate your TDEE: Multiply your BMR by your activity factor (see table above)
- Create a moderate calorie deficit: For sustainable weight loss, aim to consume 500-1000 calories less than your TDEE daily
This creates a deficit of 3,500-7,000 calories per week, resulting in 1-2 pounds of weight loss
- Never eat below your BMR: Consuming fewer calories than your BMR can:
- Slow your metabolism
- Lead to muscle loss
- Cause nutritional deficiencies
- Make weight loss harder long-term
- Adjust as you lose weight: Recalculate your BMR every 10-15 pounds lost, as it will decrease with weight loss
Example Weight Loss Calculation:
- BMR: 1,500 calories
- Activity factor: Moderately active (1.55)
- TDEE: 1,500 × 1.55 = 2,325 calories
- For weight loss: 2,325 - 500 = 1,825 calories per day
BMR and metabolic adaptation
When you lose weight, especially through severe calorie restriction, your body undergoes metabolic adaptation:
What happens:
- BMR decreases beyond what would be expected from weight loss alone
- Hormonal changes increase hunger
- Body becomes more efficient, burning fewer calories during activity
How to minimize it:
- Lose weight gradually (1-2 lbs/week)
- Maintain adequate protein intake
- Include strength training
- Take diet breaks at maintenance calories
- Avoid very low-calorie diets
This is why crash diets often lead to weight regain—they significantly lower your BMR, making it harder to maintain weight loss long-term.
Track Your Nutrition for Better Results
Knowing your BMR is just the first step. To achieve your health and fitness goals, you need to consistently track your nutrition intake.
Frequently Asked Questions
Is BMR the same as metabolism?
No. BMR is just one component of your metabolism. Your total metabolism includes BMR plus the energy used for physical activity, digestion (thermic effect of food), and other bodily processes.
Should I eat less than my BMR to lose weight?
No, you should never eat below your BMR for extended periods. Instead, create a calorie deficit by eating less than your TDEE (BMR × activity factor) but more than your BMR. This ensures your body has enough energy for basic functions.
How accurate are BMR calculators?
BMR calculators provide estimates that are typically within 10% of your actual BMR. For more precise measurements, you would need laboratory tests like indirect calorimetry. However, the Mifflin-St Jeor equation used in this calculator is considered the most accurate estimation formula.
Does BMR change with age?
Yes, BMR typically decreases by about 2-3% per decade after age 20. This is primarily due to the natural loss of muscle mass (sarcopenia) and hormonal changes that occur with aging.