BMR Calculator: Find Out Your Basal Metabolic Rate

How to Use Our BMR Calculator

To get your BMR estimate, we need a few key pieces of information. Each one plays a role in how your body uses energy.

• Age: Your metabolic rate naturally slows as you get older. Enter your age in years.

• Gender: Biological sex influences body composition and metabolic rate, as men generally have more muscle mass and a lower body fat percentage than women.

• Height: Taller individuals have more body surface area, which results in a higher BMR. Enter your height in feet and inches or centimeters.

• Weight: Your current body weight is a primary factor in determining the energy required to sustain it. Enter your weight in pounds or kilograms.

• Formula (Optional): Our calculator defaults to the Mifflin-St Jeor equation, considered the modern standard. You can also select the Revised Harris-Benedict (a classic formula) or Katch-McArdle if you know your body fat percentage for a more advanced calculation.

Understanding Your BMR Result

The number you see is your Basal Metabolic Rate (BMR). It’s an estimate of the calories your body would burn over 24 hours if you were to do nothing but rest—no eating, no moving, just basic life-sustaining functions like breathing, circulating blood, and regulating body temperature.

Think of your BMR as your body’s “idle speed.” However, you don’t stay at rest all day. To understand your actual daily calorie needs, you must account for your activity level. This is called your Total Daily Energy Expenditure (TDEE).

From BMR to TDEE: Your Actual Daily Calorie Needs

To find your TDEE, we multiply your BMR by an activity factor. This gives you a realistic estimate of the total calories you burn each day.

Example: If your BMR is 1600 calories and you are moderately active, your TDEE would be:

This TDEE of 2480 is the number of calories you need to eat daily to maintain your current weight. To lose weight, you would eat fewer calories than this; to gain weight, you would eat more.

Frequently Asked Questions About BMR & Metabolism

What’s the real difference between BMR and RMR?

BMR (Basal Metabolic Rate) and RMR (Resting Metabolic Rate) are often used interchangeably, but they have slightly different clinical definitions. BMR is a more restrictive measurement, taken in a lab after an 8-hour fast and a full night of sleep. RMR is less restrictive and estimates your resting metabolism without the strict fasting requirement, making it about 10% higher on average. For practical, non-clinical purposes, our calculator provides a BMR estimate that serves the same function as an RMR: establishing your baseline calorie burn.

Which BMR formula is the most accurate?

There isn’t a single “best” formula for everyone, but the Mifflin-St Jeor equation is widely regarded as the most accurate for the general population. A 2005 study by the American Dietetic Association found it to be the most reliable prediction method. The Revised Harris-Benedict formula is an older, but still useful, alternative. The Katch-McArdle formula can be highly accurate, but only if you have a precise measurement of your body fat percentage, which typically requires calipers, a body scan, or hydrostatic weighing. For most users, Mifflin-St Jeor is the recommended choice.

How do I use my BMR and TDEE for weight loss?

Using these numbers for weight loss involves creating a calorie deficit—consuming fewer calories than your TDEE. A safe, sustainable rate of weight loss is 1-2 pounds per week, which corresponds to a daily calorie deficit of 500-1000 calories.

Concrete Example: Let’s meet Alex. Alex is 35 years old, 5’6″ tall, weighs 170 lbs, and works a desk job but exercises 3 times per week.

1. Calculate BMR: Using the Mifflin-St Jeor formula, Alex’s BMR is approximately 1530 calories.

   $$BMR=10\times W+6.25\times H-5\times A-161$$
   $$BMR=10\times 77.1\text{ (kg)}+6.25\times 167.6\text{ (cm)}-5\times 35-161=1532\text{ calories}$$

2. Determine TDEE: Alex is moderately active.

   $$TDEE=1530\text{ (BMR)}\times 1.55\text{ (Multiplier)}=2371\text{ calories}$$

3. Create a Deficit: To lose about 1 pound per week, Alex needs a 500-calorie daily deficit.

   $$2371\text{ (TDEE)}-500\text{ (Deficit)}=1871\text{ calories}$$

To achieve a sustainable weight loss of one pound per week, Alex should aim for a daily calorie intake of around 1,870 calories.

Why does my BMR decrease as I lose weight?

This is a normal and expected part of the weight loss process. Your BMR is directly related to your total body mass. As you lose weight, your body becomes smaller and requires less energy (calories) to sustain itself at rest. This is why weight loss can sometimes plateau. It’s crucial to recalculate your BMR and TDEE every 10-15 pounds of weight loss to adjust your calorie targets accordingly and continue making progress.

Can I increase my BMR?

Yes, you can. While you can’t change your age or height, you can influence your body composition. The most effective way to increase your BMR is by building more muscle mass. Muscle tissue is more metabolically active than fat tissue, meaning it burns more calories at rest. Incorporating resistance training (weight lifting, bodyweight exercises) into your routine is the best strategy for building muscle and, in turn, increasing your basal metabolic rate.

How accurate are online BMR calculators?

Online calculators provide a very good estimate and are an excellent starting point for determining your calorie needs. They use proven scientific formulas. However, they are not a substitute for clinical measurements like indirect calorimetry, which directly measures oxygen consumption. Factors like genetics, hormonal health, and certain medications can influence your metabolism in ways a calculator cannot account for. Use this result as a reliable baseline, listen to your body, and adjust your intake based on your real-world results (your weight trend, energy levels, and hunger).

Internal Linking Suggestions

Now that you understand your calorie baseline, take the next step in refining your nutrition plan with our Macro Calculator to see how your calories should be divided between protein, carbs, and fats.

If you’re focused on weight loss, our Calorie Deficit Calculator can help you set precise targets for a safe and effective journey.