BMR Calculator: Find Your Basal Metabolic Rate Easily

Your Basal Metabolic Rate (BMR) is your body's calorie needs at complete rest. It is the energy required for basic life-sustaining functions. This includes breathing, circulation, and cell production.

Understanding your metabolic rate is the first step toward any fitness goal. It helps with weight management, whether you aim for weight loss or muscle gain.

Why Your BMR Matters

Your BMR represents the largest part of your daily calorie burn. For most people, it accounts for 60-75% of total daily energy expenditure (TDEE). The rest comes from physical activity and digesting food (the thermic effect of food).

Knowing your BMR provides a scientific starting point for your diet plan.

How to Calculate Your BMR

You can calculate BMR using scientifically developed equations. The most common BMR calculator formulas are below.

For the best results, measure your weight in kilograms and your height in centimeters.

1. The Mifflin-St Jeor Equation (Most Accurate)

This is the gold standard for the general population.

• 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

2. The Revised Harris-Benedict Equation

An older, classic formula still in common use.

• For Men: BMR = (13.397 × weight in kg) + (4.799 × height in cm) - (5.677 × age in years) + 88.362
• For Women: BMR = (9.247 × weight in kg) + (3.098 × height in cm) - (4.330 × age in years) + 447.593

3. The Katch-McArdle Formula (Best for Lean Body Mass)

This formula uses lean body mass. It is best for those who know their body fat percentage.

• Formula: BMR = 370 + (21.6 × Lean Body Mass in kg)

What Changes Your Metabolic Rate?

Your BMR is not static. Many factors influence your metabolism:

• Body Composition: Muscle burns more calories than fat. More muscle mass means a higher BMR.
• Age: Your metabolic rate often slows with age.
• Genetics: Some people inherit a faster or slower metabolism.
• Hormones: Thyroid hormones significantly impact metabolic regulation.

BMR vs. RMR: Know the Difference

People often use Basal Metabolic Rate (BMR) and Resting Metabolic Rate (RMR) interchangeably. The difference is small but important.

• BMR requires strict clinical measurement after fasting and rest.
• RMR is measured under less strict conditions.

For practical purposes, the values are very similar. Most calorie calculator tools use the terms interchangeably.

From BMR to Your Total Daily Calories (TDEE)

Your BMR is just your resting calories. To find your Total Daily Energy Expenditure (TDEE), multiply your BMR by an activity factor:

• Sedentary (little 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 a week): BMR × 1.725
• Extra active (very hard exercise & physical job): BMR × 1.9

This TDEE number is your maintenance calories. You would consume fewer calories than your TDEE for weight loss.

Using Your BMR Calculation Effectively

Remember, all formulas are estimates. For a truly accurate measure, professionals use a test called indirect calorimetry.

Use your calculated BMR and TDEE as a powerful starting guide. Track your food intake and progress. Adjust your calories based on your real-world results to meet your health goals.

For more on nutrition, read our guide on macronutrients. To understand how exercise fits in, see our article on TDEE and activity.

• The National Institutes of Health (NIH) offers a body weight planner tool based on these principles.
• A study on PubMed compares the Mifflin-St Jeor and Harris-Benedict equations.