BMR Calculator

About the BMR Calculator

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — just to keep your heart beating, lungs breathing, and organs functioning. BMR is the foundation of every calorie-based nutrition plan, and knowing yours precisely is the first step to accurate calorie targets for weight loss, maintenance, or muscle gain. Our BMR calculator uses the Mifflin-St Jeor equation, which is the most accurate formula validated by clinical research.

How It Works

The Mifflin-St Jeor equation calculates BMR based on your weight, height, age, and biological sex. For men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. A 30-year-old man weighing 80kg at 178cm has a BMR of approximately 1,844 calories/day. This is the absolute minimum calories needed to sustain basic life functions — actual calorie needs are higher once activity is factored in via TDEE.

Tips & Best Practices

• ✓BMR accounts for 60-75% of total daily calorie expenditure for most sedentary people.
• ✓Muscle mass significantly raises BMR — each pound of muscle burns about 6 calories/day at rest.
• ✓BMR decreases with age by roughly 2% per decade after age 20, primarily due to muscle loss.
• ✓Severely restricting calories below BMR triggers metabolic adaptation and muscle loss.
• ✓Multiply your BMR by 1.2 (sedentary) to 1.9 (very active) to get your TDEE.

Who Uses This Calculator

Nutritionists, personal trainers, and anyone following a structured diet plan use BMR as the starting point for calorie targets. Medical professionals use it to calculate nutritional requirements for patients with illness or injury. Understanding your BMR prevents both dangerous under-eating and unintentional overeating.