BMI Calculator – Free Body Mass Index Calculator for Adults
Use this BMI calculator to determine your Body Mass Index and understand your weight category. Based on the World Health Organization (WHO) standards, this calculator evaluates your BMI using your height and weight to help you assess whether you're underweight, normal weight, overweight, or obese.
This calculator is ideal for adults looking to monitor their health metrics, track weight loss progress, or understand their baseline metabolic rate. Get instant BMI results, health category classification, and personalized insights including BMR (Basal Metabolic Rate) and healthy weight ranges.
Check your BMI in seconds and understand what it means for your health.
- Enter your age, gender, height, and current weight.
- The calculator computes your BMI using the standard formula: weight (kg) ÷ [height (m)]².
- Your BMI is compared against WHO classification standards to determine your category.
- View your Basal Metabolic Rate (BMR) calculated using the Mifflin-St Jeor equation.
- See your healthy weight range and personalized health insights based on your results.
Clinical Screening Notice
This tool is a screening metric only. BMI does not directly measure body fat or metabolic health. Consult a licensed medical professional for a comprehensive health assessment.
Your Complete BMI Guide
BMI is a simple way to check if your weight is healthy for your height. Our calculator uses the same standards as the World Health Organization (WHO) and CDC, and also shows you how many calories your body burns at rest (BMR) and your healthy weight range.
How We Calculate Your BMI
BMI is calculated using your weight and height. While it doesn't tell the difference between muscle and fat, it's still the most widely used method to check if your weight is in a healthy range.
Metric (kg/cm)
BMI = mass (kg) ÷ [height (m)]²Imperial (lbs/inches)
BMI = 703 × mass (lb) ÷ [height (in)]²Good to Know
BMI looks at your overall weight but can't tell muscle from fat. However, research shows that higher BMI is linked to increased health risks for most people.
Adult BMI Stratification (WHO Standards)
| Clinical Range | Health Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy Range |
| 25.0 – 29.9 | Overweight |
| 30.0 and Above | Obese |
Expert Tips for Healthy Weight
Based on the latest nutrition science, here are 20 simple tips to help you reach and maintain a healthy weight.
Prioritize Protein
Aim for 0.8g-1.2g of protein per kg of body weight to preserve muscle while losing fat.
Hydration Logic
Drink 500ml of water 30 minutes before meals to naturally reduce calorie intake.
NEAT Optimization
Increase Non-Exercise Activity Thermogenesis by taking stairs or standing while working.
Calories Your Body Burns at Rest (BMR)
While BMI checks if your weight is healthy, BMR tells you how many calories your body burns just to keep you alive (breathing, heart beating, etc.) even when you're completely at rest.
BMR Formula
Men: (10 × W) + (6.25 × H) - (5 × A) + 5Women: (10 × W) + (6.25 × H) - (5 × A) - 161W=weight in kg, H=height in cm, A=age in years. Most accurate formula for adults.
Total Daily Calories (TDEE)
TDEE = BMR × Activity MultiplierMultipliers range from 1.2 (Sedentary) to 1.9 (Very Active).
Additional Health Measurements
Body Fat Estimate
* All measurements (waist, neck, hip, height) must be in inches for these constants.
Men: 86.010 × log10(waist - neck) - 70.041 × log10(height) + 36.76Women: 163.205 × log10(waist + hip - neck) - 97.684 × log10(height) - 78.387Hamwi Ideal Weight Model
Biological Male
48.0 kg + 2.7 kg per inch over 5'0"
Biological Female
45.5 kg + 2.2 kg per inch over 5'0"
Disclaimer: The Hamwi formula is provided as a historical reference and is not intended as a modern diagnostic health standard or clinical target.
Statistical observations indicate that clinical markers in the obese range (30+) may correlate with higher incidences of the following metabolic associations:
- Type 2 Diabetes Mellitus
- Hypertension (Chronic High BP)
- Ischemic Heart Disease
- Obstructive Sleep Apnea
- Osteoarthritis (Weight-bearing joints)
- Non-alcoholic Fatty Liver Disease
Trusted Health Standards
We use the same BMI standards and formulas recommended by the world's leading health organizations. No guesswork, just proven science.
Verified Formulas
All our formulas are scientifically proven and used by health professionals worldwide.
Privacy
Your health data is processed locally and never stored on our servers.
Important Things to Know
BMI is a useful starting point, but it's not the whole picture. For a complete health assessment, your doctor will also check your blood pressure, cholesterol, lifestyle habits, and family history.
BMI Doesn't Measure Muscle
Athletes and very muscular people may show as "Overweight" on BMI even though they have low body fat. For a more accurate body fat measurement, you'd need special tests like a DEXA scan.
Different Standards for Different Groups
Healthy BMI ranges can vary by ethnicity. Also, for older adults, a slightly higher BMI (25–27) may actually be healthier for maintaining muscle and bone strength.