BMR Calculator

Modify the values and click the Calculate button to use

US Units
Metric Units
ages: 2 - 120
feet inches
pounds

Result

1,650 calories/day
(Basal Metabolic Rate)
1,650
BMR/Day
Mifflin-St Jeor BMR
1,650 cal/day
Harris-Benedict BMR
1,680 cal/day
Katch-McArdle BMR
1,620 cal/day
TDEE (Sedentary)
1,980 cal/day

Energy Expenditure by Body System

Body System Percentage of BMR Calories (based on 1650 BMR)
Liver 27% 446
Brain 19% 314
Skeletal Muscle 18% 297
Kidneys 10% 165
Heart 7% 116
Other Organs 19% 314

BMR Calculator Introduction

The Basal Metabolic Rate (BMR) Calculator estimates the number of calories your body needs to perform its most basic (basal) functions, such as breathing, circulation, and cell production. This is the energy your body expends at complete rest.

Understanding BMR

Your Basal Metabolic Rate (BMR) is the number of calories your body burns while at rest to maintain vital functions such as breathing, circulating blood, and regulating body temperature. It accounts for approximately 60-75% of your total daily energy expenditure.

Factors Affecting BMR

The number of calories you burn at rest depends on various factors including:

  • Age (BMR decreases with age)
  • Gender (men typically have higher BMR)
  • Height and weight (larger bodies require more energy)
  • Body composition (muscle burns more calories than fat)
  • Genetics
  • Hormones and health conditions

BMR Calculation Formulas

This calculator uses the Mifflin-St Jeor Equation, which is considered one of the most accurate formulas for calculating BMR:

For Men:
BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) + 5
For Women:
BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) - 161

This calculator also provides estimates using the Harris-Benedict and Katch-McArdle formulas for comparison.

BMR vs. TDEE

While BMR represents the calories burned at complete rest, your Total Daily Energy Expenditure (TDEE) includes all activities throughout the day. To estimate your TDEE, multiply your BMR by an activity factor:

Activity Level Description Multiplier
Sedentary Little or no exercise BMR × 1.2
Lightly active Light exercise 1-3 days/week BMR × 1.375
Moderately active Moderate exercise 3-5 days/week BMR × 1.55
Very active Hard exercise 6-7 days/week BMR × 1.725
Extra active Very hard exercise & physical job BMR × 1.9

Ways to Increase BMR

While genetics play a role, there are several ways to naturally increase your BMR:

  • Build muscle through strength training
  • Stay properly hydrated
  • Eat adequate protein
  • Get enough sleep
  • Manage stress levels
  • Include high-intensity interval training (HIIT)
  • Don't severely restrict calories

Signs of Low BMR

  • Persistent fatigue
  • Difficulty losing weight
  • Feeling cold frequently
  • Hair loss
  • Irregular menstrual cycles
  • Poor concentration
  • Slow recovery from exercise
  • Constipation
  • Depression or low mood

Medical Conditions Affecting BMR

  • Thyroid disorders
  • Diabetes
  • Metabolic syndrome
  • Cushing's syndrome
  • Polycystic ovary syndrome (PCOS)
  • Adrenal fatigue
  • Chronic stress
  • Eating disorders
  • Certain medications

Limitations of BMR Calculators

While BMR calculators provide a good estimate of your resting energy needs, they have limitations. They don't account for individual variations in metabolism, body composition, or specific health conditions. For personalized metabolic assessment, consult a registered dietitian or healthcare provider.