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BMR Calculator

Calculate your Basal Metabolic Rate and daily calorie needs.

Basal Metabolic Rate (BMR) Calculator

Basal Metabolic Rate (BMR) represents the number of calories your body needs to perform basic life-sustaining functions while at complete rest. Think of it as how much fuel your body burns just to stay alive.

For most people, nearly 70% of daily calories burned come from maintaining vital organs such as the heart, brain, lungs, liver, kidneys, muscles, and nervous system.

What Exactly Is BMR?

BMR is measured under strict conditions: you must be awake, fully rested, in a neutral temperature, and not digesting food. In this state, energy is used only for essential bodily functions.

BMR and Daily Calories

Your total daily calorie needs are estimated by multiplying your BMR by an activity factor ranging from 1.2 to 1.9, depending on your lifestyle and exercise habits.

BMR Calculation Formulas

Mifflin-St Jeor Equation (Most Accurate)

Men: BMR = 10W + 6.25H − 5A + 5
Women: BMR = 10W + 6.25H − 5A − 161
Revised Harris-Benedict Equation

Men: BMR = 13.397W + 4.799H − 5.677A + 88.362
Women: BMR = 9.247W + 3.098H − 4.330A + 447.593
Katch-McArdle Formula (Lean Mass Based)

BMR = 370 + 21.6 × (1 − F) × W
W = weight (kg), H = height (cm), A = age, F = body fat %

Factors That Influence BMR

BMR vs Resting Metabolic Rate (RMR)

While often used interchangeably, BMR and RMR are not identical. RMR measures calories burned at rest under less strict conditions, while BMR requires complete physiological equilibrium.

How Accurate Is BMR?

Even under laboratory conditions, studies show up to a 26% variation in metabolic rates between individuals. This means all BMR-based calorie calculations are estimates, not exact values.

Tracking food intake, exercise, and results over time is the most reliable way to fine-tune calorie needs and reach health or fitness goals.

Frequently Asked Questions

Is BMR the same as TDEE?

No. BMR is calories burned at complete rest, while TDEE includes physical activity and digestion.

Which BMR formula should I use?

Mifflin-St Jeor is best for most people. Katch-McArdle is ideal if you know your body fat percentage.

Can BMR change over time?

Yes. Age, muscle mass, diet, hormones, and activity level all influence BMR over time.

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