⚕️ BMI Calculator
Calculate your Body Mass Index (BMI) to check whether your weight falls in a healthy range for your height.
Your Measurements
Your Result
| Category | BMI Range |
|---|---|
| Underweight | Below 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25 – 29.9 |
| Obesity | 30 and above |
BMI is a screening tool, not a diagnostic tool. It does not account for muscle mass, bone density, or body composition. Consult a healthcare provider for a full assessment.
How the BMI Calculator Works
Body Mass Index (BMI) is a simple screening measure that uses your height and weight to estimate whether you're in a healthy weight range. It's calculated the same way for adults regardless of age or sex.
Formula
Imperial: BMI = 703 × weight (lb) / [height (in)]²
BMI Categories (Adults)
- Below 18.5 — Underweight
- 18.5–24.9 — Normal weight
- 25–29.9 — Overweight
- 30 and above — Obesity
Full BMI Chart
| BMI | Category |
|---|---|
| Below 16.0 | Severely Underweight |
| 16.0 – 18.4 | Underweight |
| 18.5 – 24.9 | Normal / Healthy Weight |
| 25.0 – 29.9 | Overweight |
| 30.0 – 34.9 | Obesity (Class 1) |
| 35.0 – 39.9 | Obesity (Class 2, Severe) |
| 40.0 and above | Obesity (Class 3, Morbid) |
BMI Calculator for Women vs. Men
The BMI formula and the standard adult BMI chart above are identical for men and women — the CDC, WHO, and NHS all use the same calculation and category thresholds regardless of sex, since BMI is a simple height-to-weight ratio rather than a body-composition measurement. That said, women naturally tend to carry a higher percentage of body fat than men at the same BMI, which is one reason BMI alone is an incomplete picture — pairing it with a Body Fat Calculator gives a fuller view.
Limitations of BMI
BMI does not directly measure body fat and can be less accurate for athletes with high muscle mass, older adults, and pregnant women. It's best used as a general screening tool alongside other health measures like waist circumference and body fat percentage. For a target weight based on your frame rather than just your BMI range, see the Ideal Weight Calculator or Lean Body Mass Calculator.
Frequently Asked Questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range, according to the CDC and WHO.
Is the BMI calculator different for women vs. men?
No — the BMI formula and category thresholds (underweight, normal, overweight, obese) are the same for adult men and women. Some online tools brand a "BMI calculator for women" or "for men," but the underlying calculation is identical; only reference body-fat-percentage ranges differ by sex, not BMI itself.
Is BMI accurate for everyone?
BMI is a useful general screening tool but can be less accurate for athletes, bodybuilders, elderly people, and pregnant women because it doesn't distinguish between fat and muscle mass.
How is BMI different for children?
Children and teens are assessed using age- and sex-specific BMI percentiles compared against CDC growth charts, rather than the fixed adult categories used on this page. This calculator is intended for adults 20 and older; for a child's BMI, ask their pediatrician for a growth-chart percentile assessment.
What BMI is needed for gastric sleeve or bariatric surgery?
General clinical guidelines commonly cite a BMI of 40+ (Class 3 obesity), or 35+ with an obesity-related condition such as type 2 diabetes or hypertension, as typical eligibility thresholds for bariatric surgery like a gastric sleeve — but exact criteria vary by surgeon, insurer, and country. This is general information only; eligibility must be confirmed with a bariatric surgery team.