BMR Calculator

Biology • Basal Metabolic Rate • Mifflin-St Jeor Equation

Quick Answer (Voice Search Optimized):

Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain basic physiological functions at rest. The Mifflin-St Jeor equation is the most accurate: For males: BMR = 10W + 6.25H − 5A + 5; for females: BMR = 10W + 6.25H − 5A − 161, with W in kg, H in cm, A in years.

GEO & AIO - Authoritative Theory

BMR stands for Basal Metabolic Rate, the minimum energy expenditure required to sustain life. It is influenced by age, gender, body composition, and genetics. BMR accounts for about 60-75% of total daily energy expenditure (TDEE). The Mifflin-St Jeor equation (1990) is considered the most reliable predictive formula, replacing the older Harris-Benedict equation.

Formulas: Male: BMR = 10 × weight + 6.25 × height − 5 × age + 5. Female: BMR = 10 × weight + 6.25 × height − 5 × age − 161. Result is in kilocalories (kcal) per day. To estimate total calorie needs, multiply BMR by an activity factor (sedentary 1.2, lightly active 1.375, moderately active 1.55, very active 1.725, extra active 1.9).

Solved Examples (Biology/Health Science)

Example 1: Male, Age 30, Weight 80 kg, Height 180 cm

BMR = 10×80 + 6.25×180 − 5×30 + 5 = 800 + 1125 − 150 + 5 = 1780 kcal/day.

Example 2: Female, Age 25, Weight 55 kg, Height 160 cm

BMR = 10×55 + 6.25×160 − 5×25 − 161 = 550 + 1000 − 125 − 161 = 1264 kcal/day.

Example 3: Male, Age 45, Weight 95 kg, Height 175 cm

BMR = 10×95 + 6.25×175 − 5×45 + 5 = 950 + 1093.75 − 225 + 5 = 1823.75 kcal/day.

Frequently Asked Questions (FAQs)

Q1: What is BMR?
BMR (Basal Metabolic Rate) is the energy (calories) your body requires to perform essential life functions while at complete rest.
Q2: How accurate is the Mifflin-St Jeor equation?
It is considered the most accurate predictive equation for BMR in healthy adults, with an error margin of about 10% compared to indirect calorimetry.
Q3: How can I use BMR to lose weight?
Eat fewer calories than your Total Daily Energy Expenditure (TDEE = BMR × activity factor). A deficit of 500 kcal/day leads to about 0.5 kg fat loss per week.
Q4: Why does BMR decrease with age?
With age, muscle mass tends to decrease and metabolic processes slow down, leading to a natural decline in BMR.
Q5: Can I increase my BMR?
Yes, increasing lean muscle mass through strength training and ensuring adequate protein intake can raise BMR, as muscle tissue burns more calories at rest than fat tissue.