Find Your Basal Metabolic Rate

How many calories does your body burn just to stay alive — before you take a single step or lift a single weight? That number is your Basal Metabolic Rate (BMR), and it's the foundation of every calorie and nutrition plan. Our free BMR calculator estimates this number instantly using five scientifically validated formulas, so you can see exactly how many calories your body needs at complete rest.

Whether you're building a nutrition plan from scratch, fine-tuning your calorie targets, or simply curious about your metabolism, this calculator gives you a clear, comparable breakdown across multiple trusted formulas — not just a single estimate.

Enter your height, weight, age, and gender below to calculate your BMR.

This calculator provides an estimate only. Actual metabolic rate can vary based on individual factors such as genetics, hormones, and muscle mass. Please consult your doctor or a nutrition professional for personalized advice.

What Is BMR and Why Does It Matter?

Your Basal Metabolic Rate is the number of calories your body burns at complete rest just to perform essential functions — breathing, circulating blood, regulating body temperature, and repairing cells. It typically accounts for 60–75% of the total calories you burn in a day, making it the single biggest factor in determining your daily calorie needs.

Understanding your BMR is the first step toward building an accurate nutrition plan. Once you know your BMR, you can factor in your activity level to calculate your Total Daily Energy Expenditure (TDEE) — the number that actually determines whether you should eat more, less, or the same to reach your goal.

How Is BMR Calculated?

There's no single "correct" way to calculate BMR — researchers have developed several different formulas over the past century, each with its own strengths. Our calculator lets you compare results across all of them side-by-side:

• Mifflin-St Jeor – Developed in 1990, this is considered the most accurate formula for the general population and is the current standard used by most dietitians and nutrition professionals.
• Harris-Benedict – One of the original BMR equations, dating back to 1919 and revised in 1984. Still reasonably reliable but tends to slightly overestimate calorie needs compared to newer formulas.
• Katch-McArdle – Calculates BMR based on lean body mass rather than total body weight, making it significantly more accurate for lean, athletic, or muscular individuals who know their body fat percentage.
• Cunningham – Similar in approach to Katch-McArdle and widely used among athletes and bodybuilders, also based on lean body mass.
• WHO Formula – Developed by the World Health Organization for broader population health assessments, using age- and gender-based equations.

Because each formula can produce a slightly different result, our calculator also shows an Average across all applicable formulas — giving you a balanced, well-rounded estimate rather than relying on just one equation.

Which BMR Formula Is Most Accurate for You?

• If you don't know your body fat percentage: Use Mifflin-St Jeor — it's the most broadly validated formula for the general population and requires only your age, height, weight, and gender.
• If you're lean or muscular and know your body fat percentage: Use Katch-McArdle or Cunningham — both calculate BMR from lean body mass, which is far more accurate for people with an athletic build, since muscle burns more calories than fat.
• If you want a general population benchmark: The WHO Formula or Harris-Benedict can offer a useful comparison point, though they're generally considered less precise than Mifflin-St Jeor for most modern populations.
• If you're not sure which to trust: Select Average to see a blended estimate across all five formulas.

From BMR to Daily Calorie Needs

Your BMR alone doesn't tell you how many calories to eat — it only tells you what your body burns at rest. To find your actual daily calorie needs, that number needs to be multiplied by an activity factor based on how much you move and train each day:

• Sedentary (little to no exercise): 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

This adjusted number is your TDEE (Total Daily Energy Expenditure) — the real number you should use to plan calorie intake for weight loss, maintenance, or muscle gain. For a full personalized breakdown including calories, macros, and goal-based targets, try our Calorie Calculator.

Frequently Asked Questions

What is a normal BMR? BMR varies significantly by age, gender, height, and weight, so there's no single "normal" number. For most adults, BMR typically falls somewhere between 1,200 and 2,000 calories per day, though it can be higher for larger or more muscular individuals.

Why do different BMR formulas give different results? Each formula was developed using different research populations and methods. Older formulas like Harris-Benedict tend to run slightly higher, while newer ones like Mifflin-St Jeor are generally considered more accurate for today's population. Formulas based on lean body mass, like Katch-McArdle, adjust for body composition, which the others don't.

Does muscle mass affect BMR? Yes. Muscle tissue burns more calories at rest than fat tissue, so individuals with more muscle mass typically have a higher BMR than those with the same weight but a higher body fat percentage.

Is BMR the same as TDEE? No. BMR is the calories your body burns at complete rest. TDEE adds your activity and exercise on top of your BMR, giving you your true total daily calorie burn.

Does BMR decrease with age? Generally, yes. BMR tends to gradually decline with age, largely due to a natural loss of muscle mass over time. Maintaining muscle through resistance training can help offset this decline.

How often should I recalculate my BMR? Recalculate every few months, or any time you experience a significant change in weight, muscle mass, or age bracket, to keep your estimate accurate.

This calculator provides an estimate only. Actual metabolic rate can vary based on individual factors such as genetics, hormones, medical conditions, and muscle mass. Please consult your doctor or a qualified nutrition professional for personalized advice.