BMR (Mifflin-St Jeor) Calculator

Calculate your Basal Metabolic Rate using the most accurate and widely-used Mifflin-St Jeor equation.

Frequently Asked Questions

What is BMR and why is it important?

Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions at rest. It represents the minimum energy required for vital processes like breathing, circulation, and cellular maintenance.

Why does the Mifflin-St Jeor equation consider sex and age?

Men typically have more muscle mass and less body fat than women, resulting in higher metabolic rates. Age affects BMR because muscle mass tends to decrease and metabolic efficiency changes as we get older.

How should I use my BMR for fitness goals?

BMR is your baseline calorie need. For weight loss, eat below your Total Daily Energy Expenditure (TDEE = BMR × activity factor). For weight gain, eat above TDEE. Never eat significantly below BMR for extended periods.

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