A BMR calculator is a free online tool that estimates your Basal Metabolic Rate—the number of calories your body burns at rest. It uses your age, weight, height, and sex to calculate how much energy your body needs just to keep you alive and functioning.

BMR calculators using the Mifflin-St Jeor formula are accurate within 10% for about 90% of people. Your actual BMR could be 100-200 calories higher or lower than the estimate. The best way to verify accuracy is to track your weight and calorie intake for 2-3 weeks and adjust based on real results.

BMR varies significantly by sex, weight, and height, but typical ranges are: Women 20-40 years: 1,300-1,550 calories; Men 20-40 years: 1,650-2,000 calories. Your BMR naturally decreases by 2-3% per decade after age 30. What matters most isn't whether your BMR is 'good' or 'bad,' but using it correctly to plan your nutrition.

No, you shouldn't eat just your BMR calories. Instead, calculate your TDEE (Total Daily Energy Expenditure) by multiplying your BMR by an activity factor, then eat 300-500 calories below your TDEE. Eating only your BMR would create too aggressive a deficit for most people, leading to fatigue, muscle loss, and metabolic slowdown.

Yes! The most effective way to increase BMR is building muscle through strength training. Each pound of muscle burns 6-10 extra calories per day at rest. Other strategies include eating enough protein, getting 7-9 hours of sleep, managing stress, and avoiding extreme calorie restriction which can lower metabolism.

BMR (Basal Metabolic Rate) is calories burned at complete rest, while TDEE (Total Daily Energy Expenditure) includes all daily activity. TDEE = BMR × activity factor (usually 1.2-1.9). For example, if your BMR is 1,500 and you're moderately active, your TDEE would be 1,500 × 1.55 = 2,325 calories per day.

Recalculate your BMR every 10-15 pounds of weight loss, or every 2-3 months if maintaining weight. Your BMR decreases as you lose weight because you have less body mass to maintain. Don't recalculate more frequently, as daily weight fluctuations don't reflect real metabolic changes.

Several factors can result in a lower BMR: being older (BMR decreases with age), being female (women typically have 5-10% lower BMR than men), having less muscle mass, genetics, or metabolic adaptation from prolonged dieting. If your BMR seems abnormally low with symptoms like fatigue or unexplained weight gain, consult a doctor about thyroid function.