BMI Calculator — Check Your Body Mass Index
Use our free body mass index calculator (BMI calculator) to check your body mass index in seconds. You can calculate your BMI online here: enter your height and weight to see your BMI category and whether you're in the healthy range.
A body mass index calculator uses your height and weight to compute your BMI—a simple number used by the World Health Organization (WHO) to classify adult body weight. This is an adult BMI calculator (18+); it works for both women and men and uses the standard formula with metric units (kg and cm) recommended by health organisations worldwide. You can enter your height and weight in metric (cm, kg) or imperial (ft/in, lb); we convert everything internally to metric for the formula.
What does BMI mean?
BMI stands for body mass index. It is a simple ratio of your weight to your height, used as a screening tool to see whether your weight is in a range often linked to lower or higher health risks. The body mass index does not diagnose any condition—it only gives you a number and a category (underweight, normal weight, overweight, or obesity). For personalised advice, you can speak with a healthcare provider.
How to Calculate BMI
You can calculate your BMI online in seconds with the form above. The body mass index formula is: divide your weight in kilograms by your height in metres squared (kg/m²). Our calculator does this for you: enter your height in cm and weight in kg, then click "Calculate BMI" to check your result. The same BMI equation is used worldwide for adults. This adult BMI calculator uses metric units (kg and cm); if you prefer pounds and inches, convert to metric first or use an imperial BMI calculator.
BMI formula and units
The BMI formula is: weight (kg) ÷ height (m)². For example, if you weigh 70 kg and are 1.75 m (175 cm) tall, your BMI = 70 ÷ (1.75 × 1.75) ≈ 22.9. The body mass index formula is the same for all adults. We use metric units (cm and kg) as recommended by the WHO; if you use pounds and inches, convert to metric or use an imperial BMI calculator.
BMI Categories and Ranges
The BMI classification below follows the standard body mass index chart used by the WHO. The table shows the four main categories; a healthy BMI and normal BMI range fall between 18.5 and 24.9.
What is a healthy BMI?
A healthy BMI for adults is between 18.5 and 24.9—this is the normal BMI range. It's the range associated with the lowest health risks for most people. The same healthy BMI range applies to both women and men. If your result is in this band, the aim is often to maintain your weight through balanced eating and activity.
Overweight and obesity BMI ranges
An overweight BMI is between 25.0 and 29.9. Obesity (bmi obese) is a BMI of 30.0 or higher. These ranges are screening tools, not a diagnosis. If your result falls here, many people benefit from small, sustainable changes in diet and activity; our calorie deficit calculator and diet guides can support that.
| BMI range | Classification |
|---|---|
| < 18.5 | Underweight |
| 18.5 – 24.9 | Normal weight |
| 25.0 – 29.9 | Overweight |
| ≥ 30.0 | Obesity |
Important: BMI is an approximate indicator and does not reflect body composition (muscle vs fat). In very muscular people, the result may suggest overweight despite low body fat.
BMI for Women and Men
There is no separate BMI calculator for women and men—the same formula and BMI categories apply to all adults. Whether you're looking for a BMI calculator for women or a BMI calculator for men, this tool works the same: enter your height and weight to get your result. For under-20s, BMI is interpreted differently (e.g. using percentiles); authoritative health sources offer guidance for that.
BMI Chart (Height and Weight)
The table above works as your BMI chart and body mass index chart: match your calculated BMI to the correct category (underweight, normal, overweight, or obese). For a full BMI chart by height and weight, many health sites offer printable versions; the ranges shown here are the same.
When to recalculate your BMI
It's useful to check your BMI again when your weight has changed noticeably (for example by 5 kg or more), when you start or change a diet or exercise plan, or every few months if you're tracking your weight over time. Recalculating helps you see whether you're moving toward your goal (e.g. a healthy BMI range) and when to adjust habits.
Limitations and Disclaimer
BMI does not account for body composition—muscle mass versus body fat—so very muscular people may get a result in the overweight range despite having low body fat. It is a screening tool, not a diagnosis. This tool is based on WHO and widely used clinical guidelines.
Disclaimer: This tool is for education only. Results are estimates. For personalised advice, consider speaking with a healthcare provider.
Related Calculators
After checking your BMI, you might find these tools useful: our calorie calculator for daily calories to maintain or lose weight; our calorie deficit calculator to set a daily target; and our WHR calculator for body fat distribution.
Frequently asked questions
A BMI calculator uses your height and weight to compute your Body Mass Index (BMI), a number that helps classify whether you are underweight, normal weight, overweight, or obese. Enter your height and weight in the form above to get your result.
You can calculate BMI by dividing your weight in kilograms by your height in metres squared (kg/m²). Our calculator does this for you: enter your height in cm and weight in kg and click "Calculate BMI".
The BMI formula is: weight (kg) ÷ height (m)². For example, if you weigh 70 kg and are 1.75 m tall, your BMI = 70 ÷ (1.75 × 1.75) ≈ 22.9.
A healthy BMI for adults is usually between 18.5 and 24.9—this is the normal range. Below 18.5 is classed as underweight; 25–29.9 as overweight; and 30 or above as obesity. The same ranges apply to both women and men. If your BMI is in the healthy band, the focus is often on keeping it there with balanced eating and regular activity.
No. The same BMI formula and categories are used for adult women and men. Our calculator works for everyone; just enter your height and weight.
The normal BMI range for adults is 18.5 to 24.9. This is the range associated with the lowest health risks for most people.
An overweight BMI means a result between 25 and 29.9. It's a screening indicator, not a diagnosis—it suggests that for many people, improving diet and activity can reduce health risks. Our calorie deficit calculator and diet guides can help you set realistic goals.
This calculator is for adults (18+). For under-20s, BMI is interpreted differently (e.g. using percentiles). Authoritative health sources offer guidance for that age group.
BMI is based only on height and weight and doesn't measure body fat directly. For body composition, a body fat calculator or other methods may be used alongside BMI.
The BMI categories table on this page works as a BMI chart: it shows the ranges for underweight, normal, overweight, and obese. You can match your result to the correct category.
Explore diets
Depending on your BMI and goals, a diet can help you get to a healthy weight or keep it. Browse all 40 diet guides or try these:
Weight loss diet
Balanced eating with a calorie deficit for sustainable weight loss.
Mediterranean diet
Plant-forward eating with olive oil, fish and vegetables. Often recommended for heart health.
DASH diet
Low sodium, plenty of potassium. Designed to support healthy blood pressure.
Low-carb diet
Fewer carbs, more protein and fat. Used for weight loss and blood sugar.
Content quality
Written by DietaBest Editorial Team
Medically reviewed by Dr. Alex Novak, MD (Internal Medicine)
Last updated:
This guide is for general education only and does not replace personal medical advice. Always talk to your doctor or a registered dietitian before making major diet or lifestyle changes, especially if you have a medical condition or take medication.