Calculate your Body Mass Index instantly with health category and ideal weight range.
⚖️ Open BMI CalculatorFree · No signup · No data stored · Instant results
The ToolForge BMI Calculator helps you calculate your Body Mass Index instantly using your height and weight. BMI is a standard measure used by health professionals to assess whether a person's weight is within a healthy range. Our calculator supports both metric (kg/cm) and imperial (lbs/inches) units, provides your BMI category, and shows the ideal healthy weight range for your height.
Instant BMI calculation in metric and imperial
BMI category: Underweight, Normal, Overweight, Obese
Ideal weight range for your height
Visual BMI scale with your position highlighted
Supports all age groups including children
WHO standard BMI classifications used
No signup, no ads, completely private
Type your height in cm or feet and inches using the unit toggle.
Type your weight in kg or lbs.
Your BMI score and health category appear instantly with an explanation.
Track BMI changes during a fitness program to measure progress over time.
Get a quick health snapshot before a doctor visit or routine checkup.
Use for biology, health science or physical education assignments.
Check whether children's weight is within a healthy range for their age and height.
BMI (Body Mass Index) is calculated by dividing your weight in kilograms by the square of your height in meters. The resulting number falls into one of four categories: Underweight (below 18.5), Normal weight (18.5-24.9), Overweight (25-29.9) or Obese (30 and above). These categories are defined by the World Health Organization and are used globally by health professionals.
The ToolForge BMI Calculator makes this calculation instant and accurate. You don't need to remember the formula or do manual math — just enter your height and weight and get your result in under a second.
While BMI is a useful screening tool, it has limitations. It does not account for muscle mass, bone density, age or gender differences. Athletes with high muscle mass may have a high BMI despite being healthy. The elderly may have a normal BMI despite low muscle mass. Always consult a healthcare professional for a complete health assessment.
All calculations happen in your browser. No personal health data is sent to any server or stored anywhere.
A healthy BMI range is 18.5 to 24.9. Below 18.5 is underweight, 25-29.9 is overweight, and 30 or above is considered obese by WHO standards.
BMI = weight(kg) / height(m)². For example, 70kg at 1.75m gives 70 / (1.75 × 1.75) = 22.9, which is in the normal range.
BMI is a general screening tool and may not be accurate for athletes with high muscle mass, elderly individuals, or pregnant women. Consult a doctor for a full health assessment.
Yes. Toggle between metric (kg/cm) and imperial (lbs/inches) — the calculator handles the conversion automatically.
Yes, completely free with no signup required. Your health data is never stored or sent to any server.
Free · Metric & Imperial · WHO standard · No signup
⚖️ Open BMI Calculator