BMI Calculator
Free BMI Calculator — Check Your Body Mass Index
This free BMI calculator shows your body mass index, your weight category and the weight range that counts as healthy for your height. Enter your height and weight, add your age and gender if you like, and you also get your BMI Prime, Ponderal Index and a realistic goal with a timeline.
Quick answer: a BMI between 18.5 and 24.9 is a healthy weight for most adults. Below 18.5 is underweight, 25 to 29.9 is overweight and 30 or more is obese. The calculator works in centimeters, feet and inches, kilograms and pounds, and the formula is the same for men and women.
How the BMI Formula Works
Divide your weight in kilograms by your height in meters squared. Someone who weighs 70 kg and is 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75), which is about 22.9, in the normal range.
BMI Chart: Categories for Adults
| Category | BMI range | What it suggests |
|---|---|---|
| Underweight | Below 18.5 | Possible low body weight or nutritional deficiency |
| Normal weight | 18.5 – 24.9 | Healthy range for most adults |
| Overweight | 25 – 29.9 | Higher weight than recommended for your height |
| Obese | 30 and above | Linked with a higher risk of serious health conditions |
BMI Prime divides your BMI by 25, the top of the healthy range, so a value under 1.0 is within it. The Ponderal Index divides weight by height cubed and can suit very tall or very short people better. The calculator also shows your healthy weight range and how far you are from it.
Is BMI Accurate?
BMI is a screening tool, not a diagnosis. It cannot tell muscle from fat, so athletes can score high while being healthy, and older adults can score normal while carrying little muscle. It is not designed for children, teenagers or pregnant women. Read it alongside waist size, body fat and your doctor's advice. For a closer look at body composition, try the body fat calculator, and to see the calories behind your weight use the calorie calculator.
What to Do With Your BMI Result
If your BMI is in the healthy range, keep up the habits that got you there and recheck every few months. If it is below 18.5, focus on regular meals with enough protein and calories, and speak to a doctor if the weight loss was unintended. If it is 25 or above, small, steady changes work best: more daily movement, smaller portions and fewer sugary drinks. Losing 5 to 10 percent of your body weight can improve blood pressure and blood sugar for many people. The weight goal in the calculator shows a target and a realistic timeline.
Who Should Use a BMI Calculator?
It suits adults who want a quick check on their weight, people starting a fitness or weight loss plan, and anyone tracking progress over time. A result outside the healthy range is a reason to look closer, not a verdict. The ideal weight calculator can show how your weight compares with common targets for your height, and a doctor can put the number in context.
How to Use This BMI Calculator
Enter your height
Type your height and choose cm, ft, or in from the dropdown.
Enter your weight
Type your weight and choose kg or lb.
Add your age and gender
Optional — it helps tailor the advice in your result.
Click "Calculate"
Your BMI, category, health risk, BMI Prime, Ponderal Index, healthy weight range and weight goal appear instantly.