Calculate your Body Mass Index (BMI). Understand your weight category and whether you are at a healthy weight.
This guide is for educational purposes and is not medical advice. See our Disclaimer and consult a qualified healthcare professional before making changes to your diet or exercise routine.
Body Mass Index (BMI) is a simple calculation using a person's height and weight. It is an inexpensive and easy screening method for sorting people into weight categories: underweight, healthy weight, overweight, and obesity. Doctors and public health organizations use it as a quick first look at whether your weight may pose a risk to your health, before deciding whether more detailed assessments are needed.
The idea behind BMI is straightforward: it compares your weight to your height so that tall and short people can be evaluated on the same scale. Because it only needs two measurements you already know, it has become one of the most widely used health screening numbers in the world.
BMI can be calculated with either imperial or metric units. This page uses the imperial formula, which multiplies your weight in pounds by 703, then divides by your height in inches squared:
The factor of 703 in the imperial version simply converts the result so it matches the metric scale, letting both formulas share the same category ranges. The result is a single number, usually between about 15 and 40 for most adults, that you then compare against the standard weight-status ranges shown below.
Getting your result with the tool above takes just a few seconds:
For the most meaningful result, use recent measurements taken without heavy clothing or shoes. Weighing yourself at a consistent time of day, such as first thing in the morning, keeps your readings comparable over time.
Suppose someone weighs 160 pounds and is 70 inches tall. Plugging those numbers into the imperial formula:
A BMI of 23.0 falls within the 18.5 to 24.9 range, so this person would be classified as Normal or Healthy Weight. You can confirm this by entering 160 and 70 into the calculator above.
The standard weight status categories associated with BMI ranges for adults are same for men and women of all body types and ages.
| BMI Range | Weight Status |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Normal or Healthy Weight |
| 25.0 – 29.9 | Overweight |
| 30.0 and Above | Obese |
BMI is a screening tool, not a diagnosis. It estimates body size but cannot measure body composition or health directly, so it has several important blind spots:
For a fuller picture of your health, treat BMI as a starting point and combine it with other measures such as waist circumference, body fat percentage, blood pressure, and blood work reviewed by a healthcare professional.
Your BMI category is a prompt to look a little closer, not a verdict. Here is a sensible next step for each outcome:
Because BMI cannot see body composition, pairing it with our Body Fat Calculator gives you a clearer read on how much of your weight is fat versus lean tissue. To turn any of this into action, estimate your targets with the Calorie Calculator and browse our diet plans for structured, realistic eating guidance.
No. BMI is a screening tool, not a diagnostic one. It does not distinguish between muscle mass and body fat, so athletes may be classified as 'overweight' despite having low body fat.
For most adults, a healthy BMI falls between 18.5 and 24.9. However, this range can vary based on ethnicity and age.
Yes. Older adults often have more body fat than younger adults with the same BMI. Conversely, children use separate BMI percentile charts.
BMI estimates whether your weight is healthy for your height, but it cannot tell how much of that weight is fat versus muscle, bone, or water. Body fat percentage measures fat specifically as a proportion of total body weight. Because two people with the same BMI can have very different body compositions, body fat percentage often gives a more precise picture of health, especially for very muscular or very lean individuals.
Not always. Muscle is denser than fat, so athletes and people who strength train regularly can carry more weight and register a higher BMI while still having low body fat and good metabolic health. For these individuals, measures such as body fat percentage or waist circumference give a clearer assessment than BMI alone.
For most adults, checking BMI every few months, or whenever your weight changes noticeably, is enough to track trends over time. BMI naturally fluctuates a little day to day with hydration and food intake, so the long-term direction matters more than any single reading. If you are actively working on a weight goal, a monthly check-in is a reasonable rhythm.
The standard adult BMI categories are the same for men and women, so the calculation and the healthy range of 18.5 to 24.9 do not change by sex. However, at the same BMI, women tend to have more body fat than men on average. This is one reason BMI is treated as a general screening tool rather than a direct measure of body fat.
BMI is just one number. Start a comprehensive plan to reach your ideal weight today.
Calculate Daily CaloriesThe information on this page is based on guidance from the following authoritative sources:
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