BMI (Body Mass Index) is a number calculated from height and weight that is used as a screening tool to categorize weight status. It is calculated as weight (kg) divided by height (m) squared. BMI does not directly measure body fat but correlates with body fat for most adults.

What is a healthy BMI range?

According to the CDC and WHO, BMI categories for adults are: Underweight = below 18.5, Normal weight = 18.5–24.9, Overweight = 25–29.9, Obese = 30 and above. These categories are the same for men and women.

How is BMI calculated?

BMI = weight (kg) / height (m)². In imperial: BMI = 703 × weight (lbs) / height (inches)². For example, someone who is 5'9" (175 cm) and weighs 160 lbs (72.6 kg): BMI = 72.6 / (1.75²) = 72.6 / 3.0625 ≈ 23.7 (Normal weight).

Is BMI accurate for everyone?

BMI is a useful screening tool but has limitations. It may overestimate body fat in athletes (high muscle mass) and underestimate it in older adults who have lost muscle. It does not account for where fat is distributed in the body. BMI is not recommended for children (use BMI-for-age percentile instead) or pregnant women.

What is a good BMI for women vs men?

The standard BMI categories (18.5–24.9 = normal) are the same for both men and women. However, women naturally have higher body fat percentages than men at the same BMI. Some researchers suggest that 20–24.9 may be optimal for women and 22–24.9 for men, but the standard ranges are used clinically for both.

BMI Calculator – Body Mass Index for Adults

BMI — Metric

Height (cm)

Weight (kg)

BMI Categories (CDC)

BMI	Category
Below 18.5	Underweight
18.5 – 24.9	Normal
25 – 29.9	Overweight
30 and above	Obese

Source: CDC / WHO. Consult a healthcare provider for personalized advice.

BMI Calculator FAQ

Common questions about Body Mass Index.

What is BMI and how is it calculated?

BMI = weight (kg) ÷ height (m)². In imperial: BMI = 703 × weight (lbs) ÷ height (inches)².

Example: 5'9" tall (175 cm), 160 lbs (72.6 kg):
BMI = 72.6 ÷ (1.75)² = 72.6 ÷ 3.0625 ≈ 23.7 (Normal weight)

What is a healthy BMI?

According to the CDC and WHO:

Below 18.5 — Underweight
18.5–24.9 — Normal weight (healthy)
25–29.9 — Overweight
30 and above — Obese

These categories are the same for adult men and women.

Is BMI accurate for athletes?

BMI can overestimate body fat in athletes because muscle is denser than fat. A muscular person may have a BMI in the "overweight" range while having a very low body fat percentage. BMI is a screening tool, not a diagnostic one — body composition tests (DEXA scan, skinfold) are more accurate for athletes.

What is the healthy weight range for my height?

Calculate using: min weight = 18.5 × height(m)², max weight = 24.9 × height(m)².

For 5'9" (1.75 m): Min = 18.5 × 3.0625 = 56.7 kg (125 lbs), Max = 24.9 × 3.0625 = 76.3 kg (168 lbs).
The calculator above shows this range automatically after calculating.

Is BMI different for men and women?

Clinically, the same BMI categories apply to both sexes. However, women naturally carry about 5–10% more body fat than men at the same BMI. Some health researchers suggest gender-specific thresholds, but the standard CDC/WHO scale (18.5–24.9 = normal) is used universally in clinical settings.

BMI Calculator

BMI — Metric

BMI — Imperial

BMI Calculator FAQ