Basal Metabolic Rate (BMR) Calculator

BMR Calculator: Discover Your Basal Metabolic Rate

BMR (Basal Metabolic Rate) represents the minimum amount of energy your body consumes at rest to keep vital functions active: breathing, blood circulation, brain activity, body temperature regulation, and cell regeneration. Knowing your BMR is the first step to effectively managing your weight and nutrition.

What Is Basal Metabolic Rate

Basal metabolic rate accounts for approximately 60-75% of your total daily energy expenditure. It represents the energy your body would burn if you stayed in bed all day without doing absolutely anything. Even during sleep, your body burns calories to keep your heart, lungs, brain, and all other organs functioning.

The Mifflin-St Jeor Formula

This calculator uses the Mifflin-St Jeor formula, considered the most accurate among predictive equations for basal metabolic rate by the scientific community:

For men:
BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5

For women:
BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161

Calculation Example

Let's take a 35-year-old man, 178 cm tall and weighing 80 kg:

BMR = (10 x 80) + (6.25 x 178) - (5 x 35) + 5 = 800 + 1,112.5 - 175 + 5 = 1,742.5 kcal/day

This means his body burns approximately 1,743 calories per day just for vital functions, without considering any physical activity.

From BMR to Total Daily Energy Expenditure (TDEE)

To obtain your actual daily caloric needs, the BMR must be multiplied by an activity factor:

• Sedentary (little or no exercise) — BMR x 1.2
• Lightly active (light exercise 1-3 days/week) — BMR x 1.375
• Moderately active (moderate exercise 3-5 days/week) — BMR x 1.55
• Very active (intense exercise 6-7 days/week) — BMR x 1.725
• Extremely active (professional athlete) — BMR x 1.9

In the previous example, if the man were moderately active: 1,743 x 1.55 = approximately 2,702 kcal/day.

Factors That Affect Basal Metabolic Rate

BMR is not the same for everyone and depends on multiple variables:

• Muscle mass — muscle burns more energy than fat, even at rest
• Age — metabolism slows by approximately 2% every decade after age 20
• Sex — men generally have a higher BMR due to greater muscle mass
• Genetics — influences the base metabolic rate
• Thyroid hormones — hyperthyroidism and hypothyroidism significantly alter BMR
• Ambient temperature — cold increases metabolism to produce heat

How to Use the Result

Knowing your BMR is essential for any weight management goal. To lose weight, you need to create a caloric deficit relative to your TDEE (not your BMR). It is recommended to never go below your basal metabolic rate to avoid nutritional deficiencies and metabolic slowdown. Always consult a nutritionist for a personalized meal plan.