BMI Calculator Online — Free, Instant Results
Check your Body Mass Index (BMI) to understand your health status.
Want your daily calorie target too? Try the calorie & TDEE calculator.
About This Tool
Calculate your BMI with metric or imperial units
BMI (Body Mass Index) is a widely used health metric that helps assess whether you're at a healthy weight for your height. Our calculator supports both metric (kg/cm) and imperial (lbs/inches) units, with instant health category classification.
Privacy guaranteed. All calculations happen locally in your browser — no personal data is stored or transmitted.
Metric, Imperial & Stone
kg/cm, lbs/inches, or stone (UK) — your choice.
Healthy Range & Ideal Weight
See your healthy range and how much to lose or gain.
BMI Gauge
A visual scale shows exactly where your BMI sits.
Waist-to-Hip Ratio
Built-in WHR tab with WHO health-risk bands.
WHO Categories
Underweight to obese, classified automatically.
100% Private
Calculated in your browser — nothing stored.
Imperial Units
BMI Calculator (Imperial) — Feet, Inches & Pounds
To calculate your BMI in imperial units, select Imperial (lb / ft) in the toggle at the top, then enter your height in feet and inches and your weight in pounds. You can also switch the weight unit to stone for the UK format.
The imperial BMI formula is: BMI = (weight in lbs ÷ height in inches²) × 703. Example: 154 lb at 5'9" (69 in) → (154 ÷ 4761) × 703 ≈ 22.7, a normal-weight BMI.
Metric Units
BMI Calculator (Metric) — Kilograms & Centimetres
To calculate your BMI in metric units, select Metric (kg / cm) in the toggle at the top, then enter your weight in kilograms and your height in centimetres. The calculator converts your height to metres automatically.
The metric BMI formula is: BMI = weight in kg ÷ height in m². Example: 70 kg at 175 cm (1.75 m) → 70 ÷ 3.0625 ≈ 22.9. The BMI value and WHO category are identical to the imperial result for the same person — only the input units differ.
Reference
BMI Categories (WHO Standard)
< 18.5
Underweight
18.5 – 24.9
Normal Weight
25 – 29.9
Overweight
≥ 30
Obesity
Reference
Waist-to-Hip Ratio Categories (WHO)
Waist-to-hip ratio (waist ÷ hip) shows where you carry fat. The WHO health-risk thresholds differ by sex — calculate yours in the Waist-to-Hip Ratio tab above.
Women
Men
Your Healthy Weight Range & Ideal Weight
A healthy BMI is 18.5–24.9, which maps to a specific weight range for your height. The calculator shows that range in kg, pounds, or stone, a target (ideal) weight at BMI 22, and exactly how much to lose or gain to get there — so the number turns into an actionable goal.
To plan how to reach it, the calorie and TDEE calculator shows your daily calorie target for losing, maintaining, or gaining weight.
Why Check Your Waist-to-Hip Ratio Too
BMI compares weight to height but ignores where you carry fat. Waist-to-hip ratio (WHR) — waist divided by hip — reflects fat distribution, which research links more directly to heart-health risk. It’s especially useful for muscular builds, where BMI alone can overstate body fat.
Switch to the Waist-to-Hip Ratio tab above to calculate yours and see the WHO risk band for your sex (elevated above 0.85 for women, 0.90 for men).
Use Cases
When to Use BMI Calculator
BMI is a quick screening tool used by individuals, healthcare providers, and fitness professionals to assess weight relative to height.
Health Screening
Get a quick overview of whether your weight falls within a healthy range for your height.
Fitness Goal Setting
Use your current BMI as a baseline to set realistic weight loss or muscle gain targets.
Pre-Appointment Check
Calculate BMI before a doctor or nutritionist appointment to arrive informed.
Progress Tracking
Track BMI changes over weeks or months to measure the impact of diet and exercise changes.
Family Health Monitoring
Check BMI for family members of different ages and heights to monitor overall household health.
Insurance & Medical Forms
Calculate BMI to fill in health questionnaires, insurance forms, or medical intake documents.
FAQ
Frequently Asked Questions
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat mass, so athletes may have high BMI despite being healthy. Best used alongside other health indicators.
A BMI between 18.5 and 24.9 is generally considered healthy for adults. Ideal BMI can vary based on age, sex, muscle mass, and ethnicity. Consult a healthcare provider for personalized advice.
Yes, BMI interpretation can vary with age. Older adults may have a slightly higher healthy BMI range. Children and teens use age and sex-specific BMI percentiles rather than adult categories.
BMI may not be accurate for very muscular individuals, as muscle weighs more than fat. Athletes and bodybuilders may have high BMI despite low body fat. Consider body composition analysis.
Yes. Select Imperial in the unit toggle to enter your height in feet and inches and your weight in pounds. The BMI result and health category are identical regardless of which unit system you use.
Switch to Imperial mode, enter your height (feet and inches separately) and your weight in pounds, then click Calculate. The tool uses the imperial BMI formula: weight (lbs) ÷ height (in)² × 703.
Imperial BMI = (weight in lbs ÷ height in inches²) × 703. The metric formula is weight in kg ÷ height in metres². Both produce the same result for the same person — only the input units differ.
No — the BMI value is the same regardless of unit system. The formulas differ but produce identical results. The health categories (Underweight, Normal, Overweight, Obesity) apply equally to both.
A healthy weight is a BMI of 18.5–24.9. The calculator shows your exact range in kg, pounds, or stone, plus how much to lose or gain to reach it.
The tool shows a target weight at BMI 22 (mid healthy range) as a BMI-based ideal. Your personal ideal also depends on age, sex, and muscle mass.
Yes. Set the weight unit to 'st' to enter stone and pounds (UK format). It converts automatically and reports your healthy range in stone too.
WHR is waist ÷ hip. The WHO flags it above 0.85 for women and 0.90 for men. Use the Waist-to-Hip Ratio tab to calculate yours and see the risk band.
Both. BMI compares weight to height; WHR shows fat distribution, which is more directly linked to heart risk — especially useful for muscular builds where BMI overstates fat.