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BMI & Health Calculator

Q: What is Body Mass Index (BMI) and how is it calculated?

Body Mass Index (BMI) is a medical screening metric that estimates body fatness based on an adult's height and weight. The standard formula is: BMI = Weight (kg) / [Height (m)]². For imperial units, the formula is: BMI = 703 × Weight (lbs) / [Height (inches)]².

Q: What are the official WHO BMI categories for adults?

According to the World Health Organization (WHO):\n• Underweight: BMI below 18.5\n• Normal (Healthy Weight): BMI 18.5 to 24.9\n• Overweight: BMI 25.0 to 29.9\n• Obesity Class I: BMI 30.0 to 34.9\n• Obesity Class II: BMI 35.0 to 39.9\n• Obesity Class III (Severe/Morbid): BMI 40.0 and above.

Q: What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the minimum energy your body burns strictly to sustain involuntary life functions (breathing, organ function, cellular repair) at complete bed rest. TDEE (Total Daily Energy Expenditure) is your total daily calorie burn after factoring in your physical activity level, work, and exercise.

Q: Are BMI calculations accurate for bodybuilders and athletes?

BMI is a general population screening tool, not a diagnostic measure of body composition. Because muscle is significantly denser than fat, muscular athletes and bodybuilders may register as "overweight" or "obese" despite having very low body fat. For athletic individuals, the U.S. Navy Body Fat tab provides a much more accurate assessment.

Q: How many calories should I eat per day to lose weight?

To lose weight safely, health authorities recommend a daily caloric deficit of 500 calories below your TDEE, which produces a steady fat loss of approximately 0.5 kg (1 lb) per week. Women should generally avoid consuming fewer than 1,200 calories per day, and men should not consume fewer than 1,500 calories per day without physician supervision.

Calculate your Body Mass Index (BMI), ideal weight range, Basal Metabolic Rate (BMR), daily calorie needs (TDEE), and body fat percentage with instant visual gauges.

Body Mass Index (BMI) Calculator

Gender:

Male Female

Age (Years):

yrs

Height:

Weight:

Your Body Mass Index (BMI):

22.9

Normal Weight (Healthy)

16.0 (Under) 18.5 (Normal) 25.0 (Over) 30.0 (Obese) 40.0+

Healthy Weight Range

56.7 - 76.3 kg

Weight Goal (to BMI 22)

Ideal (0 kg)

Ponderal Index

13.1 kg/m³

WHO Health Risk

Low Risk

Basal Metabolic Rate (BMR) & Daily Calories (TDEE)

Mifflin-St Jeor Medical Formula

Daily Physical Activity Level:

Basal Metabolic Rate (BMR): 1,685 Calories/day

BMR represents the baseline calories your body burns at complete rest to keep your heart beating, lungs breathing, and cells functioning.

Target Calories Based on Your Health Goal:

Maintain Weight

2,317

Calories / Day (100%)

Mild Weight Loss (-0.25 kg/wk)

2,067

Calories / Day (-250 cal)

Weight Loss (-0.5 kg/wk)

1,817

Calories / Day (-500 cal)

Healthy Weight Gain (+0.5 kg/wk)

2,817

Calories / Day (+500 cal)

WHO Clinical Standards

Calculated using official World Health Organization classifications for adults.

Metric & Imperial Units

Instantly toggle between kilograms/centimeters and pounds/feet-inches seamlessly.

100% In-Browser Privacy

Your health measurements execute purely in local JavaScript without server storage.

BMI Result copied to clipboard!

Quick Guide

How to Use BMI & Health Calculator?

Follow these 4 simple steps to get your work done in seconds.

Select Unit System & Gender

Choose your preferred measurement unit: Metric (kilograms and centimeters) or Imperial (pounds, feet, and inches), and select your biological gender.

Enter Your Age, Height & Weight

Input your height and current body weight. The tool automatically computes your exact Body Mass Index (BMI) in real-time as you type.

Inspect the Visual Color-Coded Gauge

View the interactive WHO BMI scale indicator to see whether your weight falls into the Underweight, Normal, Overweight, or Obese category.

Explore Calories & Ideal Weight

Switch between tabs to calculate your daily calorie maintenance needs (TDEE/BMR), target weight goals, and body fat percentage estimates.

Comprehensive Health & Fitness Guide

Everything You Need to Know About Body Mass Index (BMI), Ideal Weight & Daily Calories

Maintaining a healthy weight is one of the most effective strategies for preventing chronic cardiovascular diseases, type-2 diabetes, hypertension, and joint degeneration. Our free, clinical-standard BMI & Health Calculator combines the World Health Organization (WHO) BMI classifications, Mifflin-St Jeor Basal Metabolic Rate calculations, medical Ideal Body Weight formulas, and U.S. Navy anthropometric body fat estimations into one seamless, privacy-focused online tool.

WHO Body Mass Index (BMI) Classification Table

The World Health Organization classifies adult weight categories as follows:

BMI Range (kg/m²)	WHO Weight Classification	Clinical Health Risk Level
< 18.5	Underweight	Increased risk of nutritional deficiency & osteoporosis
18.5 – 24.9	Normal Weight (Healthy)	Lowest risk of cardiovascular and metabolic illness
25.0 – 29.9	Overweight (Pre-obese)	Moderate risk of elevated blood pressure & cholesterol
30.0 – 34.9	Obesity Class I	High risk of type 2 diabetes and coronary heart disease
35.0 – 39.9	Obesity Class II	Very high risk of metabolic syndrome & sleep apnea
≥ 40.0	Obesity Class III (Severe)	Extremely high health risk requiring clinical intervention

Understanding BMR vs. TDEE for Caloric Control

Basal Metabolic Rate (BMR)

The energy consumed by vital organs while you sleep or stay motionless in bed. Computed using the peer-reviewed Mifflin-St Jeor equation.

Total Daily Energy Expenditure (TDEE)

Your true daily maintenance calories calculated by multiplying your BMR by your physical activity multiplier (1.2x to 1.9x).

Caloric Deficit for Fat Loss

To lose 0.5 kg (1 lb) of body fat per week, aim for a consistent 500-calorie daily deficit below your TDEE through balanced nutrition and exercise.

Clinical Ideal Body Weight (IBW) Formulas

Rather than relying on a single number, medical professionals analyze multiple historical equations:

Devine Formula (1974): The gold standard in pharmacokinetics and drug dosage calculation.
Robinson Formula (1983): An empirical refinement of the Devine formula with improved statistical correlation.
Miller Formula (1983): Developed to account for muscular frame variations across adult populations.
Hamwi Formula (1964): A classic rule of thumb used widely by clinical dietitians.

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FAQ

Frequently Asked Questions (FAQ)

Find quick answers to common questions about this tool.

What is Body Mass Index (BMI) and how is it calculated?

Body Mass Index (BMI) is a medical screening metric that estimates body fatness based on an adult's height and weight. The standard formula is: BMI = Weight (kg) / [Height (m)]². For imperial units, the formula is: BMI = 703 × Weight (lbs) / [Height (inches)]².

What are the official WHO BMI categories for adults?

According to the World Health Organization (WHO):\n• Underweight: BMI below 18.5\n• Normal (Healthy Weight): BMI 18.5 to 24.9\n• Overweight: BMI 25.0 to 29.9\n• Obesity Class I: BMI 30.0 to 34.9\n• Obesity Class II: BMI 35.0 to 39.9\n• Obesity Class III (Severe/Morbid): BMI 40.0 and above.

What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the minimum energy your body burns strictly to sustain involuntary life functions (breathing, organ function, cellular repair) at complete bed rest. TDEE (Total Daily Energy Expenditure) is your total daily calorie burn after factoring in your physical activity level, work, and exercise.

Are BMI calculations accurate for bodybuilders and athletes?

BMI is a general population screening tool, not a diagnostic measure of body composition. Because muscle is significantly denser than fat, muscular athletes and bodybuilders may register as "overweight" or "obese" despite having very low body fat. For athletic individuals, the U.S. Navy Body Fat tab provides a much more accurate assessment.

How many calories should I eat per day to lose weight?

To lose weight safely, health authorities recommend a daily caloric deficit of 500 calories below your TDEE, which produces a steady fat loss of approximately 0.5 kg (1 lb) per week. Women should generally avoid consuming fewer than 1,200 calories per day, and men should not consume fewer than 1,500 calories per day without physician supervision.

BMI & Health Calculator

Body Mass Index (BMI) Calculator

Basal Metabolic Rate (BMR) & Daily Calories (TDEE)

Target Calories Based on Your Health Goal:

Ideal Body Weight (IBW) Comparison

Body Fat Percentage (U.S. Navy Method)

WHO Clinical Standards

Metric & Imperial Units

100% In-Browser Privacy

How to Use BMI & Health Calculator?

Select Unit System & Gender

Enter Your Age, Height & Weight

Inspect the Visual Color-Coded Gauge

Explore Calories & Ideal Weight

Everything You Need to Know About Body Mass Index (BMI), Ideal Weight & Daily Calories

WHO Body Mass Index (BMI) Classification Table

Understanding BMR vs. TDEE for Caloric Control

Basal Metabolic Rate (BMR)

Total Daily Energy Expenditure (TDEE)

Caloric Deficit for Fat Loss

Clinical Ideal Body Weight (IBW) Formulas

Frequently Asked Questions (FAQ)

Welcome Guest!

BMI & Health Calculator

BMI & Health Calculator

Body Mass Index (BMI) Calculator

Basal Metabolic Rate (BMR) & Daily Calories (TDEE)

Target Calories Based on Your Health Goal:

Ideal Body Weight (IBW) Comparison

Body Fat Percentage (U.S. Navy Method)

WHO Clinical Standards

Metric & Imperial Units

100% In-Browser Privacy

How to Use BMI & Health Calculator?

Select Unit System & Gender

Enter Your Age, Height & Weight

Inspect the Visual Color-Coded Gauge

Explore Calories & Ideal Weight

Everything You Need to Know About Body Mass Index (BMI), Ideal Weight & Daily Calories

WHO Body Mass Index (BMI) Classification Table

Understanding BMR vs. TDEE for Caloric Control

Basal Metabolic Rate (BMR)

Total Daily Energy Expenditure (TDEE)

Caloric Deficit for Fat Loss

Clinical Ideal Body Weight (IBW) Formulas

Frequently Asked Questions (FAQ)

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