Check your body mass index, BMI category and estimated healthy weight range. You can also add your waist measurement to calculate your waist-to-height ratio, which can give a fuller picture of weight-related health risk.
Instant result
BMI, category and healthy weight range.
Waist option
Optional waist-to-height ratio.
Adult guidance
Plain-English next steps and limitations.
BMI, or body mass index, is a simple way to compare your weight with your height. It is often used as a quick screening measure to estimate whether an adult is in an underweight, healthy weight, overweight or obesity range.
BMI is calculated as:
Example: if you weigh 70 kg and are 1.70 m tall, your BMI is 70 ÷ (1.70 × 1.70) = 24.2.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Healthy weight |
| 25 to 29.9 | Overweight |
| 30 to 34.9 | Obesity class 1 |
| 35 to 39.9 | Obesity class 2 |
| 40 or above | Obesity class 3 |
BMI guide
Body mass index, usually shortened to BMI, is a screening measure that compares your weight with your height. It can help estimate whether your weight is in a lower, healthy, overweight or obesity range for most adults.
BMI is useful because it is quick, simple and works well for broad population-level screening. However, it should not be treated as a diagnosis. It does not directly measure body fat, muscle mass, bone density, fitness, medical history or where fat is carried on the body.
BMI is commonly used because it gives a fast estimate of whether weight may be affecting health risk. It can be useful for starting a conversation about weight, nutrition, movement, blood pressure, cholesterol, blood sugar and wider health.
Two people can have the same BMI but very different body composition. For example, someone with high muscle mass may have a high BMI without having excess body fat. Someone else may have a “healthy” BMI but carry more fat around the waist, which can still matter for health risk.
BMI chart
This BMI chart shows approximate weight ranges for common adult heights. It is based on standard adult BMI cut-offs: below 18.5, 18.5 to 24.9, 25 to 29.9, and 30 or above.
Use the calculator above for a more exact result, especially if your height or weight is between the values shown in the table.
| Height | Underweight | Healthy weight | Overweight | Obesity range |
|---|---|---|---|---|
| 150 cm | Under 41.6 kg | 41.6–56.0 kg | 56.1–67.4 kg | 67.5 kg or more |
| 155 cm | Under 44.4 kg | 44.4–59.8 kg | 59.9–72.0 kg | 72.1 kg or more |
| 160 cm | Under 47.4 kg | 47.4–63.7 kg | 63.8–76.7 kg | 76.8 kg or more |
| 165 cm | Under 50.4 kg | 50.4–67.8 kg | 67.9–81.6 kg | 81.7 kg or more |
| 170 cm | Under 53.5 kg | 53.5–72.0 kg | 72.1–86.6 kg | 86.7 kg or more |
| 175 cm | Under 56.7 kg | 56.7–76.3 kg | 76.4–91.8 kg | 91.9 kg or more |
| 180 cm | Under 59.9 kg | 59.9–80.7 kg | 80.8–97.1 kg | 97.2 kg or more |
| 185 cm | Under 63.3 kg | 63.3–85.2 kg | 85.3–102.6 kg | 102.7 kg or more |
| 190 cm | Under 66.8 kg | 66.8–89.9 kg | 90.0–108.2 kg | 108.3 kg or more |
| 195 cm | Under 70.3 kg | 70.3–94.7 kg | 94.8–114.0 kg | 114.1 kg or more |
Your result gives a broad category for your weight compared with your height. It can be useful as a starting point for thinking about health, weight changes and whether to seek advice.
BMI does not measure body fat directly. It cannot tell the difference between fat, muscle and bone, and it does not show where body fat is carried.
Waist-to-height ratio can help assess fat around the middle. A simple guide is to keep your waist measurement below half your height.
Health context
BMI gives a useful starting point, but waist measurement can add important information. Carrying more weight around the middle can be linked with higher cardiometabolic risk, even when BMI alone does not tell the full story.
Waist-to-height ratio is a simple measurement that compares your waist size with your height. A common public health message is to keep your waist measurement below half your height.
Speak to a GP, pharmacist, dietitian or other qualified healthcare professional if your BMI is very low or high, your weight has changed unexpectedly, you are worried about your eating, or you have symptoms such as tiredness, breathlessness, swelling, pain or low mood.
Consider speaking to a clinician, especially if weight loss was unplanned or you feel tired, weak or unwell.
Keep focusing on balanced nutrition, movement, sleep and monitoring major weight changes.
Waist measurement may help clarify risk. Small, sustainable changes can be more realistic than rapid dieting.
A GP or clinician can help assess blood pressure, blood sugar, cholesterol and safe treatment options.
BMI stands for body mass index. It is a simple calculation that uses your weight and height to estimate whether your weight is within a lower, healthy, overweight or obesity range for most adults.
BMI is calculated by dividing your weight in kilograms by your height in metres squared. The formula is: BMI = weight in kg ÷ height in metres squared.
For most adults, a BMI from 18.5 to 24.9 is usually described as the healthy weight range. BMI is only a guide and does not measure body fat directly.
This adult BMI calculator is for adults aged 18 and over. It is not suitable for children, teenagers, pregnancy, people with an eating disorder or suspected eating disorder, or people with a condition that affects height.
BMI is useful as a quick screening tool, but it is not perfect. It does not directly measure body fat, muscle, bone density, age-related changes or fat distribution.
Waist-to-height ratio can help identify whether you may be carrying excess fat around your middle. A common guide is to keep your waist measurement below half your height.
Yes. BMI can be misleading for people with high muscle mass because it does not distinguish between muscle and fat. An athlete may have a higher BMI without having excess body fat.
Consider speaking to a GP, pharmacist, dietitian or qualified clinician if your BMI is very low or high, your weight has changed unexpectedly, you are worried about your eating or weight, or you have symptoms such as tiredness, breathlessness, swelling or low mood.
Check whether your waist size is less than half your height.
Estimate daily energy needs based on your activity level.
Check common eligibility factors for weight-loss treatment discussion.
Review lifestyle and health factors linked with heart risk.
This page provides general health information and should not replace advice from a GP, pharmacist, dietitian or other qualified healthcare professional.
BMI categories and waist-to-height guidance on this page are based on widely used public health guidance. Before publishing, add your own medical reviewer, review date and editorial policy link.
NHS guidance on adult BMI, who should use it and how BMI is calculated.
NHS guidance on measuring waist-to-height ratio alongside BMI.
NICE guidance on identifying and assessing overweight, obesity and central adiposity.
Last reviewed by AllHealthandCare editorial team: May 2026. Next review due: May 2027.