Know Your Number. Take Control of Your Health.

BMI Calculator (Body Mass Index Calculator)

Use the BMI calculator above to estimate your Body Mass Index (BMI) using your height and weight. BMI is a widely used screening tool that helps determine whether a person is underweight, at a healthy weight, overweight, or obese.For individuals struggling with obesity, BMI is also one of the primary factors doctors use to determine eligibility for bariatric surgery.

Adult BMI Calculator

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BMI is a screening measure and does not diagnose health.

What Is BMI?

Body Mass Index (BMI) is a mathematical calculation that estimates body fat using a person’s height and weight. It provides a quick and standardized way to categorize weight status in adults.

The BMI formula used in the United States is: weight (lbs) ÷ height² (inches) × 703

Although BMI does not measure body fat directly, it is widely used by healthcare providers to assess weight-related health risks.

BMI Categories for Adults

BMI Range Weight Category
Less than 18.5 Underweight
18.5 – 24.9 Healthy Weight
25 – 29.9 Overweight
30 – 34.9 Obesity Class I
35 – 39.9 Obesity Class II
40 or higher Obesity Class III (Severe Obesity)

Why BMI Matters for Your Health

A high BMI is strongly linked to several serious health conditions, including:

  • Type 2 Diabetes
  • Heart Disease
  • High Blood Pressure
  • Sleep Apnea
  • Osteoarthritis
  • GERD (acid reflux)
  • Fatty Liver Disease
  • Depression

According to the CDC, more than one-third of adults in the United States have obesity, making BMI an important screening tool for identifying health risks early.

BMI Requirements for Bariatric Surgery

BMI plays a central role in determining eligibility for weight-loss surgery. You may qualify for bariatric surgery if you:

  • Have a BMI of 40 or higher
  • Have a BMI of 35 or higher with obesity-related health conditions, such as diabetes, sleep apnea, or hypertension

Some patients may also qualify with slightly lower BMI values depending on their overall health and metabolic conditions. At BASS Bariatric Surgery Center, our specialists evaluate each patient individually to determine the most appropriate treatment plan.

BMI Is a Screening Tool, Not a Diagnosis

While BMI is helpful, it is not a perfect measure of body fat or overall health. BMI does not account for:

  • Muscle mass
  • Bone density
  • Body composition
  • Fat distribution

For example:Athletes may have a high BMI due to increased muscle mass.
Older adults may have a normal BMI but higher body fat levels.For this reason, doctors often combine BMI with other health measurements.

Waist Circumference and Metabolic Risk

Waist circumference can provide additional insight into health risks related to abdominal fat. To measure your waist:

  1. Place a tape measure just above your hip bones
  2. Ensure the tape is level around your body
  3. Measure after exhaling normally

Waist circumference can provide additional insight into health risks related to abdominal fat. To measure your waist:

Higher abdominal fat levels are associated with increased risk of:

  • Heart disease
  • Type 2 diabetes
  • Metabolic syndrome

Even individuals with a normal BMI may face health risks if they carry excess abdominal fat.

BMI Chart for Adults

The BMI chart below shows how height and weight correspond to Body Mass Index values.

BMI chart showing body mass index values by height and weight with color-coded ranges for underweight, healthy weight, overweight, and obesity.

When Diets and Injections Are Not Enough

Many patients who visit our center have tried multiple weight loss methods, including:

While some individuals see temporary results, long-term weight loss can be difficult to maintain. For patients with severe obesity, bariatric surgery remains one of the most effective long-term treatments available.

Bariatric Surgery Options at BASS

Our experienced bariatric surgery team offers several procedures designed to help patients achieve sustainable weight loss:

These procedures can lead to significant improvements in conditions such as:

  • Type 2 diabetes
  • High blood pressure
  • Sleep apnea
  • Joint pain
  • Fatty liver disease

Many patients experience improved mobility, energy levels, and overall quality of life.

Start Your Weight Loss Journey

If your BMI suggests you may be a candidate for bariatric surgery, the next step is a consultation with one of our experienced surgeons. Our team will review your medical history, discuss treatment options, and help you determine the best path forward. Request a bariatric consultation with our specialists in Walnut Creek or Brentwood today.

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Frequently Asked Questions About BMI

What BMI qualifies for bariatric surgery?

Most guidelines recommend bariatric surgery for individuals with a BMI of 40 or higher, or 35 or higher with obesity-related health conditions.

Is BMI accurate for everyone?

BMI is a screening tool and does not directly measure body fat. Healthcare providers often use additional measurements such as waist circumference, blood tests, and body composition analysis.

What BMI is considered obese?

A BMI of 30 or higher is classified as obesity.

How often should you check your BMI?

BMI can be checked periodically to monitor weight changes, but it should be interpreted alongside other health indicators.