BMI Calculator — Check Your Body Mass Index Free Online
Calculate your BMI instantly with metric (kg/cm) or imperial (lbs/ft/in) units. Get your health category, healthy weight range, ideal weight & personalised guidance — no login, no data stored.
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⚕️ This tool follows WHO & CDC BMI guidelines. Your health data is never stored.
📊 WHO BMI Classification Chart
| Category | BMI Range | Health Risk |
|---|---|---|
| 🔵 Underweight | Below 18.5 | Risk of nutritional deficiency |
| 🟢 Healthy Weight | 18.5 – 24.9 | Lowest health risk |
| 🟡 Overweight | 25.0 – 29.9 | Moderate increased risk |
| 🟠 Obese Class I | 30.0 – 34.9 | High health risk |
| 🔴 Obese Class II | 35.0 – 39.9 | Very high health risk |
| 🔴 Obese Class III | 40.0 & above | Extremely high risk |
* For Asian populations (including India), some guidelines suggest overweight threshold at BMI 23.0. Consult a healthcare professional for personalised advice.
What is the BMI Calculator?
The WorldOfTools BMI Calculator is a free, private, instant tool that calculates your Body Mass Index (BMI) using WHO and CDC standard guidelines. Enter your height and weight in metric (kg/cm) or imperial (lbs/ft/in) units and get your BMI value, health category, healthy weight range, ideal weight, and personalised guidance — all in your browser with zero data storage.
BMI is a widely used screening measure to assess weight-related health risks in adults aged 18 and above. It is calculated as weight in kilograms divided by height in metres squared (kg/m²). While it has limitations (it doesn't distinguish muscle from fat), it remains a valuable first-line health indicator.
How to Calculate BMI — Step by Step
Choose Your Unit System — Select Metric (kg/cm) if you know your weight in kilograms and height in centimetres, or Imperial (lbs/ft/in) for pounds and feet.
Enter Weight & Height — Type your weight and height. BMI calculates automatically as you type — no button needed.
Read Your Results — See your BMI value, health category on the colour gauge, healthy weight range for your height, and how much weight to gain or lose (if any) to reach the healthy zone.
Copy or Share — Click "Copy Result" to save your BMI, category, and healthy range to clipboard for reference or consultation.
Key Features — Why Use Our BMI Calculator?
- ✓Metric & Imperial Support — Switch between kg/cm and lbs/ft/in instantly. Perfect for users in India, the UK, and the US.
- ✓Animated BMI Gauge — Visual colour-coded gauge shows your BMI position across Underweight, Normal, Overweight, and Obese categories at a glance.
- ✓Healthy Range & Ideal Weight — Shows the exact weight range considered healthy for your height, and an ideal target weight (BMI 22) using the Hamwi formula.
- ✓WHO & CDC Standards — Follows official BMI classification: Underweight <18.5, Healthy 18.5–24.9, Overweight 25–29.9, Obese ≥30.
- ✓100% Private — Health Data Never Stored — Your weight and height are never uploaded to any server. All calculations run locally in your browser.
Frequently Asked Questions
What is a healthy BMI range for adults?
According to WHO and CDC guidelines, a BMI between 18.5 and 24.9 is healthy for adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese. These categories apply to adults aged 18 and above, and use the same ranges for men and women.
Is BMI accurate for Indians and Asians?
Some research suggests Asian populations have higher cardiometabolic risks at lower BMI values. The WHO proposes a lower overweight cut-off of 23.0 for Asian populations. This tool uses the standard international WHO ranges — consult a healthcare professional for personalised Asian BMI guidance.
What is the BMI formula?
Metric: BMI = weight(kg) ÷ height²(m²). Imperial: BMI = 703 × weight(lbs) ÷ height²(inches²). For example: 70kg at 175cm = 70 ÷ (1.75²) = 70 ÷ 3.0625 = 22.9.
Why might BMI be inaccurate for athletes?
BMI doesn't distinguish between muscle and fat. A professional athlete may have a "Overweight" or "Obese" BMI due to high muscle mass, despite having very low body fat. For athletes, body fat percentage and waist circumference are better health indicators.
How do I calculate ideal weight from BMI?
Ideal weight = target BMI × height²(m²). A common target is BMI 22 (midpoint of healthy range). This tool shows this automatically — for a person 175cm tall, ideal weight = 22 × 1.75² = 67.4 kg.
Is my weight and height data private?
Yes. All BMI calculations run entirely in your browser using JavaScript. Your weight and height are never uploaded to any server, never stored in any database, and never shared with anyone.
🆚 BMI Calculator vs. Other Tools
| Feature | WorldOfTools | Other Tools |
|---|---|---|
| Health Data Privacy | ✓ Browser Only | Server Upload |
| Metric + Imperial | ✓ Both | Often One Only |
| Visual BMI Gauge | ✓ Animated | Text Only |
| Ideal Weight | ✓ Shown | Rarely |
| Registration | ✓ Not Required | Often Required |