BMI Calculator

BMI is useful, but it has well-documented limitations. Understanding them helps you interpret your number more accurately.

It doesn't measure body fat directly. BMI is based only on height and weight. It cannot distinguish between fat mass, muscle mass, bone density, or water weight. An athlete with significant muscle mass may have a "high" BMI without excess body fat.

It doesn't account for fat distribution. Where your body stores fat matters for health risk. Visceral fat (around the organs) is more strongly linked to conditions like type 2 diabetes and cardiovascular disease than subcutaneous fat (under the skin). BMI doesn't capture this distinction.

It may be less accurate for certain populations. BMI can overestimate body fat in younger, more muscular individuals and underestimate it in older adults who have lost muscle mass. It also does not account for differences across ethnic groups — some populations experience weight-related health risks at lower BMI thresholds.

For a more complete picture of how your body uses energy, try our BMR calculator to estimate your basal metabolic rate — the number of calories your body burns at rest each day.

BMI plays a specific role in medical weight loss — not as a goal, but as one of several criteria used to determine treatment eligibility. Most FDA-approved weight loss medications, including GLP-1 and GIP/GLP-1 receptor agonists like semaglutide and tirzepatide, have BMI-based prescribing guidelines.

A BMI of 30 or higher (classified as obesity) generally qualifies a patient for prescription weight loss medication, even without additional health conditions.

A BMI of 27 or higher with a weight-related comorbidity — such as type 2 diabetes, hypertension, high cholesterol, or obstructive sleep apnea — also typically meets the threshold for treatment.

Insurance coverage often follows similar criteria. Many major payers cover medically supervised weight loss for patients who meet these BMI thresholds, though specific requirements vary by plan. PEAK's team handles insurance verification before your first visit so there are no surprises.

It's worth noting that BMI is a starting criterion, not the entire assessment. During your initial consultation at PEAK, your clinician reviews your full health history, current medications, lab results, and personal goals to determine whether medical treatment is appropriate — and which approach makes the most sense for you.