BMI Calculator
Analyse BMI, advanced waist metrics, metabolic rates, and progress history to guide health decisions.
Body profile
BMI Results
BMI is calculated using weight ÷ height². Values update instantly.
BMI Prime = BMI ÷ 25. Target range is 0.74 – 1.0.
Based on WHO BMI range 18.5 – 24.9 for adults.
Amount needed to reach the healthy BMI bracket.
Optimal metabolic risk profile (≤ 0.50).
Moderate risk.
Mosteller formula — commonly used for clinical dosing.
Guidance for Healthy weight
Lowest risk for weight-related health conditions.
Maintain balanced nutrition, regular activity, and monitor waist measures.
BMI interpretation
Healthy weight (18.5 – 24.9). Lowest risk for weight-related health conditions.
Waist-to-height ratio
Optimal metabolic risk profile (≤ 0.50).
Waist-hip ratio
Moderate risk.
Basal metabolic rate
Approx. 1,452 kcal/day — energy needs at rest.
Total daily energy expenditure
Approx. 2,251 kcal/day based on your activity level.
Goal planner
Set a realistic plan for reaching your target BMI.
Clamped between 16 and 35 for realistic goals.
Calculated from your goal BMI and current height.
Estimated completion: 12/2/2026
Lose 6.4 kg at 0.5 kg/week → 13 weeks · target date 12/2/2026.
Safe weight changes are typically 0.25–1 kg (0.5–2 lb) per week. Always consult a healthcare professional before major adjustments.
Saved history
Save up to 50 entries locally to track trends over time.
No saved entries yet. Save results above to build your BMI trend.
Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a screening measure that compares your weight to your height. While it does not directly measure body fat, it provides a quick snapshot of weight status categories that may indicate potential health risks.
BMI formula
BMI = weight (kg) ÷ [height (m)]². In imperial units multiply weight (lb) by 703 before dividing by height² (in²).
Adult health ranges
- Underweight: BMI < 18.5
- Healthy weight: BMI 18.5 – 24.9
- Overweight: BMI 25.0 – 29.9
- Obesity: BMI ≥ 30 (Class I 30–34.9, Class II 35–39.9, Class III ≥ 40)
How to use this calculator
- Select units: Toggle between metric (cm, kg) and imperial (ft/in, lb). All outputs update instantly.
- Enter core details: Provide age, biological sex, activity level, height, weight, and optional waist/hip values.
- Fine-tune goals: Open the goal planner to set a target BMI and weekly change to receive timeline estimates.
- Review insights: Scroll to see BMI category, healthy ranges, waist ratios, BMR/TDEE, and personalised recommendations.
- Save progress: Use Save result to log the snapshot, then visit the history tab to compare trends or export CSV.
Example scenarios
Balanced professional (metric)
Inputs: 32-year-old female, 165 cm, 62 kg, waist 74 cm, hip 96 cm, moderate activity.
Outputs: BMI 22.8 (healthy), waist-to-height 0.45 (optimal), waist-hip 0.77 (low risk), BMR ≈ 1,375 kcal, TDEE ≈ 2,130 kcal.
Goal planner suggests maintaining weight while reinforcing strength and recovery habits.
Recomposition focus (imperial)
Inputs: 45-year-old female, 5'3", 183 lb, waist 37.5 in, hip 43 in, light activity, weekly loss goal 1 lb.
Outputs: BMI 32.4 (obesity class I), waist-to-height 0.56 (elevated risk), waist-hip 0.87 (moderate), BMR ≈ 1,480 kcal, TDEE ≈ 2,140 kcal.
Goal planner estimates ~22 weeks to reach BMI 27 with gradual weight loss and highlights strength training plus nutrition coaching.
Beyond BMI: complementary metrics
BMI does not differentiate between muscle and fat mass. Combining BMI with circumference-based ratios improves risk screening, particularly for metabolic and cardiovascular conditions.
Waist-to-height ratio
Keep your waist circumference below half of your height (ratio ≤ 0.5) to minimise cardiometabolic risk.
Waist-hip ratio
Central adiposity is linked to higher risk. Aim for ratios ≤ 0.8 (female) or ≤ 0.9 (male) whenever possible.
Interpreting the dashboard
- BMI gauge & badges: Shows your category, risk statement, and tailored advice with contextual styling.
- Healthy weight range: Projects minimum/maximum weights for BMI 18.5–24.9 in both kilograms and pounds.
- Metabolic estimates: BMR is resting energy use; TDEE multiplies BMR by activity level to estimate maintenance calories.
- Waist ratios: Offer central adiposity clues that complement BMI for cardiometabolic screening.
- Goal summary ticker: Combines target BMI, weekly pace, and estimated date so you can plan milestones.
History, exports, and productivity tools
Tracking
Press Save result after each check-in to build a timeline with BMI, waist ratios, and metabolic estimates.
Toggle entries on or off, delete outdated records, or clear everything to restart.
Sharing
Use Copy summary for a quick clipboard digest or Export CSV to analyse trends in spreadsheets.
Sample profiles and reset buttons help you compare different archetypes or start fresh with default values.
Goal planning best practices
- Set realistic targets: Sustainable weight changes typically range between 0.25–1 kg (0.5–2 lb) per week.
- Look at trends: Use the history tab to monitor long-term progress instead of daily fluctuations.
- Combine habits: Pair nutrition, movement, sleep, and stress management for consistent results.
- Consult professionals: A BMI calculation is not a diagnosis. Always work with qualified health providers for personalised plans.
Tips for accurate measurements
- Measure height barefoot, standing tall against a wall.
- Weigh yourself in the morning after using the restroom for consistent readings.
- Wrap the tape snugly around the waist at the navel and around the fullest part of the hips.
- Record measurements regularly to understand your personal variability.
Disclaimer: This calculator provides educational information only. It should not replace personalised medical advice. Consult a licensed healthcare professional for diagnosis, treatment, or nutrition guidance.