BMI Calculator
Body Mass Index

Calculate your Body Mass Index (BMI) instantly with detailed health insights, ideal weight range, and personalized recommendations based on your measurements.

Your Measurements

Height

Centimeters

Feet & Inches

170 cm

Weight

Kilograms

Pounds

70 kg

Your BMI Results

24.2
Normal Weight
Low Risk
24.2
Underweight
<18.5Normal
18.5-24.9Overweight
25-29.9Obese
>30

Healthy weight range. Maintain current lifestyle.

Healthy Weight Range

53.5 kg - 72.2 kg
For your height (BMI 18.5-25)

Maintain Weight

70 kg
You're in the healthy range
Height
170 cm
Weight
70 kg
Category
Normal Weight
Health Risk
Low Risk

BMI Categories Reference

Severe Underweight
BMI < 16
Underweight
BMI 16 - 18.4
Normal Weight
BMI 18.5 - 24.9
Overweight
BMI 25 - 29.9
Obese Class I
BMI 30 - 34.9
Obese Class II+
BMI ≥ 35

Important Note: BMI serves as a general screening tool and may not precisely reflect body composition or health status for certain populations, including athletes, pregnant individuals, or older adults. For a comprehensive health evaluation, please consult qualified healthcare professionals.

Track Your Health
Journey

From weight management to fitness goals, our BMI calculator provides comprehensive health insights with personalized recommendations to help you achieve your wellness objectives.

Whether you're starting a fitness journey or monitoring your health, track with confidence using our advanced BMI calculator with BMR and TDEE analysis.

How BMI Calculation Works

Calculation Steps:

  1. 1Enter your height in centimeters or feet/inches for accurate measurement
  2. 2Input your weight in kilograms or pounds based on your preference
  3. 3Provide age, gender, and activity level for BMR and TDEE calculations
  4. 4Review your BMI score and category classification
  5. 5Check your ideal weight range based on healthy BMI thresholds
  6. 6Analyze weight goals: amount to lose, gain, or maintain
  7. 7View daily calorie needs for weight management goals

Health Tips:

  • Measure height and weight at the same time of day for consistency
  • Remove shoes and heavy clothing for accurate measurements
  • BMI is a screening tool, not a diagnostic measure of health
  • Track BMI trends over time rather than focusing on single values
  • Combine BMI with waist circumference and body fat percentage for complete picture
  • Consider ethnic and age factors when interpreting BMI results
  • Use TDEE calculations to create realistic calorie goals
  • Consult healthcare providers before starting any weight management program

Common Use Cases

Weight Loss Journey

Track progress and set realistic weight loss goals based on BMI targets

Example:
Monitor BMI from 28 (overweight) to 23 (normal) over 6 months

Fitness Goal Setting

Determine ideal weight range for your height and build fitness plans

Example:
Calculate target weight of 70kg for 175cm height to reach BMI 22.9

Health Screening

Initial assessment for health risks related to body weight

Example:
Regular BMI checks to monitor cardiovascular health indicators

Nutrition Planning

Use TDEE calculations to create personalized meal plans

Example:
TDEE of 2,200 cal/day guides daily calorie intake for maintenance

Athletic Training

Monitor body composition changes during training programs

Example:
Track BMI and weight trends while building muscle mass

Medical Consultations

Prepare BMI data for doctor appointments and health discussions

Example:
Bring BMI history to discuss weight management strategies

Frequently Asked Questions

📊 BMI Calculation Methods & Health Analysis

1 Body Mass Index (BMI) Formula

BMI is calculated using a simple mathematical formula that relates your weight to your height squared. It was developed by Belgian mathematician Adolphe Quetelet in the 1830s and remains the most widely used screening tool for weight categories.

BMI = Weight (kg) / [Height (m)]²

📏 Metric System Calculation

Formula: BMI = kg / m²
Weight: Measured in kilograms (kg)
Height: Measured in meters (m), squared
Example: 70 kg ÷ (1.75 m)² = 22.9

📐 Imperial System Calculation

Formula: BMI = (lb / in²) × 703
Weight: Measured in pounds (lb)
Height: Measured in inches (in), squared
Example: (154 lb / 69² in) × 703 = 22.7
🔢 Step-by-Step BMI Calculation Example

Given Information:

  • • Height: 175 cm (1.75 meters)
  • • Weight: 70 kg

Step 1: Convert height to meters

Height = 175 cm ÷ 100 = 1.75 m

Step 2: Square the height

Height² = 1.75 × 1.75 = 3.0625 m²

Step 3: Divide weight by height squared

BMI = 70 kg ÷ 3.0625 m² = 22.86
Result: BMI = 22.9 (Normal Weight)
📚 BMI History & Scientific Basis

Historical Development: The BMI formula was created in 1832 by Adolphe Quetelet, a Belgian astronomer, mathematician, and statistician. Originally called the "Quetelet Index," it was designed to study population-level obesity trends, not individual health assessment.

Modern Adoption: In 1972, researcher Ancel Keys renamed it "Body Mass Index" and popularized its use in medical practice. The WHO officially adopted BMI as the standard for measuring obesity in the 1980s.

Scientific Validation: Multiple epidemiological studies have shown correlations between BMI ranges and health outcomes, including cardiovascular disease, diabetes, and mortality rates. However, BMI works best as a population screening tool rather than an individual diagnostic measure.

2 Basal Metabolic Rate (BMR) - Mifflin-St Jeor Equation

BMR represents the calories your body burns at rest to maintain vital functions like breathing, circulation, and cell production. We use the most accurate Mifflin-St Jeor equation, developed in 1990 and validated by the American Dietetic Association as more accurate than the older Harris-Benedict equation.

👨 Male BMR Formula

BMR = (10 × W) + (6.25 × H) - (5 × A) + 5
W: Weight in kilograms
H: Height in centimeters
A: Age in years
+5: Male constant (higher muscle mass)

👩 Female BMR Formula

BMR = (10 × W) + (6.25 × H) - (5 × A) - 161
W: Weight in kilograms
H: Height in centimeters
A: Age in years
-161: Female constant (body composition)
🧮 BMR Calculation Example

Male, 30 years old, 175 cm, 70 kg:

BMR = (10 × 70) + (6.25 × 175) - (5 × 30) + 5
BMR = 700 + 1093.75 - 150 + 5
BMR = 1,648.75 calories/day
⚡ Factors Affecting BMR

Increases BMR:

  • • Higher muscle mass (10-15% more calories)
  • • Younger age (decreases ~2% per decade after 20)
  • • Male gender (5-10% higher than females)
  • • Pregnancy & breastfeeding (20-25% increase)
  • • Fever or illness (13% per °C increase)
  • • Cold environments (slight increase)

Decreases BMR:

  • • Aging (muscle loss over time)
  • • Calorie restriction (adaptive thermogenesis)
  • • Lower body weight
  • • Hypothyroidism (hormonal disorder)
  • • Sleep deprivation
  • • Chronic stress (prolonged cortisol elevation)

3 Total Daily Energy Expenditure (TDEE)

TDEE represents your total calorie burn including all physical activity and represents the calories needed to maintain your current weight. It accounts for your activity level by multiplying BMR with activity factors based on the Harris-Benedict principle:

TDEE = BMR × Activity Multiplier

Sedentary

1.2×

Little to no exercise

Desk job, minimal physical activity

Light

1.375×

Exercise 1-3 days/week

Light walks, casual sports

Moderate

1.55×

Exercise 3-5 days/week

Regular gym sessions, active lifestyle

Active

1.725×

Exercise 6-7 days/week

Daily intense workouts, athletic training

Very Active

1.9×

Intense exercise daily

Professional athletes, physical labor jobs

TDEE Example (Moderate Activity):

BMR: 1,648.75 calories/day × 1.55 = 2,555.56 calories/day

This is your maintenance calorie level for moderate activity (3-5 days/week exercise).

⚖️ Weight Management Guidelines

Weight Loss (Fat Loss):

• Reduce TDEE by 500 calories/day → ~0.5 kg (1 lb) loss per week

• Reduce TDEE by 1000 calories/day → ~1 kg (2 lbs) loss per week

Note: Don't go below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision

Weight Gain (Muscle Building):

• Add 300-500 calories/day → ~0.25-0.5 kg (0.5-1 lb) gain per week

• Combine with resistance training for lean muscle growth

Note: Slower gains result in more muscle, less fat accumulation

Maintenance:

• Consume calories equal to TDEE

• Adjust based on weekly weigh-ins (stable weight = accurate TDEE)

4 Privacy & Health Data Security

100% Client-Side Health Calculations

All BMI, BMR, and TDEE calculations happen entirely in your browser using JavaScript. Your sensitive health information, body measurements, and fitness data never leave your device, ensuring complete privacy and security of your personal health data.

✓ No Data Tracking: Health data stays private
✓ No Server Storage: Measurements remain on your device
✓ HTTPS Encrypted: Secure connection guaranteed
✓ Privacy First: Your health, your data

⚠️ BMI Limitations & Considerations

❌ BMI Doesn't Account For

  • •
    Muscle mass: Athletes may have high BMI despite low body fat
  • •
    Body composition: Doesn't distinguish fat from muscle
  • •
    Fat distribution: Where fat is stored matters for health
  • •
    Age differences: Older adults may need higher BMI
  • •
    Ethnic variations: Different populations have different risk thresholds

✅ Best Practices

  • •
    Use as screening tool: BMI is a starting point, not a diagnosis
  • •
    Consider other metrics: Waist circumference, body fat percentage
  • •
    Track trends: Changes over time are more meaningful than single values
  • •
    Consult professionals: Doctors can provide comprehensive assessment
  • •
    Focus on health: Weight is just one aspect of overall wellness

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